compat.go

// Copyright (C) 2017 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package gles

import (
	"context"
	"fmt"
	"reflect"
	"strings"

	"github.com/google/gapid/core/app/analytics"
	"github.com/google/gapid/core/data/dictionary"
	"github.com/google/gapid/core/log"
	"github.com/google/gapid/core/math/u32"
	"github.com/google/gapid/core/os/device"
	"github.com/google/gapid/gapis/api"
	"github.com/google/gapid/gapis/api/transform"
	"github.com/google/gapid/gapis/memory"
	"github.com/google/gapid/gapis/replay/builder"
	"github.com/google/gapid/gapis/shadertools"
)

type support int

const (
	unsupported support = iota
	supported
	required
)

var (
	// We don't include tests directly in the gles package as it adds
	// significantly to the test build time.
	VisibleForTestingCompat = compat
)

// If the default vertex array object (id 0) is not allowed on
// the target platform, we remap the uses to this array.
const DefaultVertexArrayId = VertexArrayId(0xFFFF0001)

type extensions map[string]struct{}

func listToExtensions(list []string) extensions {
	out := extensions{}
	for _, s := range list {
		out[s] = struct{}{}
	}
	return out
}

func translateExtensions(in U32ːstringᵐ) extensions {
	out := make(extensions, in.Len())
	for _, s := range in.All() {
		out[s] = struct{}{}
	}
	return out
}

func (e extensions) get(name string) support {
	if _, ok := e[name]; ok {
		return supported
	}
	return unsupported
}

func (s support) String() string {
	switch s {
	case unsupported:
		return "unsupported"
	case supported:
		return "supported"
	case required:
		return "required"
	default:
		return fmt.Sprintf("support<%d>", s)
	}
}

type features struct {
	vertexHalfFloatOES        support // support for GL_OES_vertex_half_float
	eglImageExternal          support // support for GL_OES_EGL_image_external
	textureMultisample        support // support for ARB_texture_multisample
	vertexArrayObjects        support // support for VBOs
	supportGenerateMipmapHint bool    // support for GL_GENERATE_MIPMAP_HINT
	compressedTextureFormats  map[GLenum]struct{}
	framebufferSrgb           support // support for GL_FRAMEBUFFER_SRGB
}

func getFeatures(ctx context.Context, version string, ext extensions) (features, *Version, error) {
	v, err := ParseVersion(version)
	if err != nil {
		return features{}, v, err
	}

	f := features{
		vertexHalfFloatOES:        ext.get("GL_OES_vertex_half_float"),
		eglImageExternal:          ext.get("GL_OES_EGL_image_external"),
		textureMultisample:        ext.get("ARB_texture_multisample"),
		compressedTextureFormats:  getSupportedCompressedTextureFormats(v, ext),
		supportGenerateMipmapHint: v.IsES,
	}

	// TODO: Properly check the specifications for these flags.
	switch {
	case v.AtLeastES(3, 0):
		f.vertexArrayObjects = supported
	case v.AtLeastGL(3, 0):
		f.vertexArrayObjects = required
	}

	if v.AtLeastES(3, 2) {
		f.textureMultisample = required
	}

	// GLES defaults FRAMEBUFFER_SRGB to enabled and only allows changing it via
	// an extension, while desktop GL defaults to disabled.
	if v.IsES {
		f.framebufferSrgb = ext.get("GL_EXT_sRGB_write_control")
	} else {
		f.framebufferSrgb = required
	}

	return f, v, nil
}

type onCompatError func(context.Context, api.CmdID, api.Cmd, error)

func compat(ctx context.Context, device *device.Instance, onError onCompatError) (transform.Transformer, error) {
	ctx = log.Enter(ctx, "compat")
	if device.Configuration.Drivers.Opengl == nil {
		return nil, fmt.Errorf("Could not find OpenGL device on host")
	}

	glDev := device.Configuration.Drivers.Opengl
	target, version, err := getFeatures(ctx, glDev.Version, listToExtensions(glDev.Extensions))
	if err != nil {
		return nil, fmt.Errorf(
			"Error '%v' when getting feature list for version: '%s', extensions: '%s'",
			err, glDev.Version, glDev.Extensions)
	}

	contexts := map[Contextʳ]features{}
	bufferCompat := newBufferCompat(int(glDev.UniformBufferAlignment))
	eglContextHandle := map[Contextʳ]EGLContext{}

	nextTextureID := TextureId(0xffff0000)
	newTexture := func(i api.CmdID, cb CommandBuilder, out transform.Writer) TextureId {
		s := out.State()
		id := nextTextureID
		tmp := s.AllocDataOrPanic(ctx, id)
		defer tmp.Free()
		out.MutateAndWrite(ctx, i.Derived(), cb.GlGenTextures(1, tmp.Ptr()).AddWrite(tmp.Data()))
		nextTextureID--
		return id
	}

	// Definitions of Vertex Arrays backed by client memory.
	// We postpone the write of the command until draw call.
	clientVAs := map[VertexAttributeArrayʳ]*GlVertexAttribPointer{}

	textureCompat := &textureCompat{
		f: target,
		v: version,
		origSwizzle: map[GLenum]map[Textureʳ]GLenum{
			GLenum_GL_TEXTURE_SWIZZLE_R: {},
			GLenum_GL_TEXTURE_SWIZZLE_G: {},
			GLenum_GL_TEXTURE_SWIZZLE_B: {},
			GLenum_GL_TEXTURE_SWIZZLE_A: {},
		},
		compatSwizzle: map[Textureʳ]map[GLenum]GLenum{},
	}

	// TODO: Implement full support for external images.
	convertTexTarget := func(tex interface {
		Target() GLenum
		SetTarget(GLenum)
	}) {
		t := tex.Target()
		if t == GLenum_GL_TEXTURE_EXTERNAL_OES && target.eglImageExternal == unsupported {
			// Remap external textures to plain 2D textures - this matches GLSL compat.
			// TODO: This aliases GLenum_GL_TEXTURE_EXTERNAL_OES and GLenum_GL_TEXTURE_2D
			tex.SetTarget(GLenum_GL_TEXTURE_2D)
		}
	}

	var t transform.Transformer
	t = transform.Transform("compat", func(ctx context.Context, id api.CmdID, cmd api.Cmd, out transform.Writer) {
		dID := id.Derived()
		s := out.State()
		cb := CommandBuilder{Thread: cmd.Thread(), Arena: s.Arena}
		switch cmd := cmd.(type) {
		case *EglMakeCurrent: // TODO: Check for GLX, CGL, WGL...
			// The compatibility layer introduces calls to GL functions that are defined for desktop GL
			// and for GLES 3.0+. If the trace originated on a GLES 2.0 device, these new commands' mutate
			// functions will fail the minRequiredVersion checks (which look at the version coming from
			// the original context from the trace).
			// TODO(dsrbecky): This might make some commands valid for replay which were invalid on trace.
			scs := FindStaticContextState(s.Arena, cmd.Extras())
			if !scs.IsNil() && !version.IsES && scs.Constants().MajorVersion() < 3 {
				clone := cmd.clone(s.Arena)
				clone.Extras().MustClone(cmd.Extras().All()...)
				for _, e := range clone.Extras().All() {
					if cs, ok := e.(*StaticContextState); ok {
						cs.Constants().SetMajorVersion(3)
						cs.Constants().SetMinorVersion(0)
					}
				}
				cmd = clone
			}

			// Mutate to set the context, Version and Extensions strings.
			out.MutateAndWrite(ctx, id, cmd)

			c := GetContext(s, cmd.Thread())
			if c.IsNil() || !c.Other().Initialized() {
				return
			}
			if _, found := contexts[c]; found {
				return
			}

			source, _, err := getFeatures(ctx, c.Constants().Version(), translateExtensions(c.Constants().Extensions()))
			if err != nil {
				log.E(log.V{
					"version":    c.Constants().Version(),
					"extensions": c.Constants().Extensions(),
				}.Bind(ctx), "Error getting feature list: %v", err)
				return
			}

			contexts[c] = source
			eglContextHandle[c] = cmd.Context()

			if target.vertexArrayObjects == required &&
				source.vertexArrayObjects != required {
				// Replay device requires VAO, but capture did not enforce it.
				// Satisfy the target by creating and binding a single VAO
				// which we will use instead of the default VAO (id 0).
				tmp := s.AllocDataOrPanic(ctx, VertexArrayId(DefaultVertexArrayId))
				defer tmp.Free()
				out.MutateAndWrite(ctx, dID, cb.GlGenVertexArrays(1, tmp.Ptr()).AddWrite(tmp.Data()))
				out.MutateAndWrite(ctx, dID, cb.GlBindVertexArray(DefaultVertexArrayId))
			}
			return

		case *EglCreateImageKHR:
			if target.eglImageExternal == unsupported {
				// Only mutate, don't write. EGL images are treated as regular textures.
				cmd.Mutate(ctx, id, s, nil /* builder */, nil /* watcher */)
				return
			}

			if cmd.Target() == EGLenum_EGL_NATIVE_BUFFER_ANDROID {
				// Need to create a texture, but probably don't have a context.
				// This case is handled in glEGLImageTargetTexture2DOES below.
				// Only mutate, don't write.
				cmd.Mutate(ctx, id, s, nil /* builder */, nil /* watcher */)
				return
			}

			out.MutateAndWrite(ctx, id, cmd)
			return
		}

		c := GetContext(s, cmd.Thread())
		if c.IsNil() || !c.Other().Initialized() {
			// The compatibility translations below assume that we have a valid context.
			out.MutateAndWrite(ctx, id, cmd)
			return
		}

		if cmd.CmdFlags(ctx, id, s).IsDrawCall() {
			t := newTweaker(out, dID, cb)
			disableUnusedAttribArrays(ctx, t)
			defer t.revert(ctx)
		}

		switch cmd := cmd.(type) {
		case *GlBindBuffer:
			if cmd.Buffer() == 0 {
				buf, err := subGetBoundBuffer(ctx, nil, api.CmdNoID, nil, s, GetState(s), cmd.Thread(), nil, nil, cmd.Target())
				if err != nil {
					log.E(ctx, "Can not get bound buffer: %v ", err)
				}
				if buf.IsNil() {
					// The buffer is already unbound. Thus this command is a no-op.
					// It is helpful to remove those no-ops in case the replay driver does not support the target.
					return
				}
			} else if !c.Objects().GeneratedNames().Buffers().Get(cmd.Buffer()) {
				// glGenBuffers() was not used to generate the buffer. Legal in GLES 2.
				tmp := s.AllocDataOrPanic(ctx, cmd.Buffer())
				defer tmp.Free()
				out.MutateAndWrite(ctx, dID, cb.GlGenBuffers(1, tmp.Ptr()).AddRead(tmp.Data()))
			}

		case *GlBindTexture:
			{
				cmd := cmd.clone(s.Arena)
				if cmd.Texture() != 0 && !c.Objects().GeneratedNames().Textures().Get(cmd.Texture()) {
					// glGenTextures() was not used to generate the texture. Legal in GLES 2.
					tmp := s.AllocDataOrPanic(ctx, cmd.Texture())
					out.MutateAndWrite(ctx, dID, cb.GlGenTextures(1, tmp.Ptr()).AddRead(tmp.Data()))
					defer tmp.Free()
				}

				convertTexTarget(cmd)

				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		case *GlBindVertexArray:
			if cmd.Array() == VertexArrayId(0) {
				if target.vertexArrayObjects == required &&
					contexts[c].vertexArrayObjects != required {
					// NB: This leaks state change upstream.
					// In particular, when the tweaker saves and then restores vertex array binding,
					// it will restore it to DefaultVertexArrayId instead of 0.  It is harmless.
					out.MutateAndWrite(ctx, id, cb.GlBindVertexArray(DefaultVertexArrayId))
					return
				}
			}

		case *GlBindVertexArrayOES:
			if cmd.Array() == VertexArrayId(0) {
				if target.vertexArrayObjects == required &&
					contexts[c].vertexArrayObjects != required {
					out.MutateAndWrite(ctx, id, cb.GlBindVertexArray(DefaultVertexArrayId))
					return
				}
			}
			// Translate to non-OES call.
			out.MutateAndWrite(ctx, id, cb.GlBindVertexArray(cmd.Array()))
			return

		case *GlGenVertexArraysOES:
			// Translate to non-OES call.
			c := cb.GlGenVertexArrays(cmd.Count(), cmd.Arrays())
			c.Extras().Add(cmd.Extras().All()...)
			out.MutateAndWrite(ctx, id, c)
			return

		case *GlBindBufferBase:
			if cmd.Buffer() == 0 {
				genBuf, err := subGetBoundBuffer(ctx, nil, api.CmdNoID, nil, s, GetState(s), cmd.Thread(), nil, nil, cmd.Target())
				if err != nil {
					onError(ctx, id, cmd, fmt.Errorf("Can not get bound buffer: %v", err))
				}
				idxBuf, err := subGetBoundBufferAtIndex(ctx, nil, api.CmdNoID, nil, s, GetState(s), cmd.Thread(), nil, nil, cmd.Target(), cmd.Index())
				if err != nil {
					onError(ctx, id, cmd, fmt.Errorf("Can not get bound buffer: %v", err))
				}
				if genBuf.IsNil() && idxBuf.IsNil() {
					// Both of the binding points are already clear. Thus this command is a no-op.
					// It is helpful to remove those no-ops in case the replay driver does not support the target.
					return
				}
			}

		case *GlBufferData:
			bufferCompat.modifyBufferData(ctx, out, cb, c, id, cmd.Target(), func() { out.MutateAndWrite(ctx, id, cmd) })
			return

		case *GlBufferSubData:
			bufferCompat.modifyBufferData(ctx, out, cb, c, id, cmd.Target(), func() { out.MutateAndWrite(ctx, id, cmd) })
			return

		case *GlCopyBufferSubData:
			bufferCompat.modifyBufferData(ctx, out, cb, c, id, cmd.WriteTarget(), func() { out.MutateAndWrite(ctx, id, cmd) })
			return

		case *GlBindBufferRange:
			bufferCompat.bindBufferRange(ctx, out, cb, c, id, cmd)
			return

		case *GlDisableVertexAttribArray:
			if c.Bound().VertexArray().VertexAttributeArrays().Get(cmd.Location()).Enabled() == GLboolean_GL_FALSE {
				// Ignore the call if it is redundant (i.e. it is already disabled).
				// Some applications iterate over all arrays and explicitly disable them.
				// This is a problem if the target supports fewer arrays than the capture.
				return
			}

		case *GlVertexAttrib4fv:
			if c.Vertex().Attributes().Contains(cmd.Location()) {
				oldAttrib := c.Vertex().Attributes().Get(cmd.Location())
				oldValue := oldAttrib.Value().MustRead(ctx, cmd, s, nil /* builder */)
				cmd.Mutate(ctx, id, s, nil /* builder */, nil /* watcher */)
				newAttrib := c.Vertex().Attributes().Get(cmd.Location())
				newValue := newAttrib.Value().MustRead(ctx, cmd, s, nil /* builder */)
				if reflect.DeepEqual(oldValue, newValue) {
					// Ignore the call if it is redundant.
					// Some applications iterate over all arrays and explicitly initialize them.
					// This is a problem if the target supports fewer arrays than the capture.
					return
				}
			}
			out.MutateAndWrite(ctx, id, cmd)
			return

		case *GlGetVertexAttribIiv,
			*GlGetVertexAttribIuiv,
			*GlGetVertexAttribPointerv,
			*GlGetVertexAttribfv,
			*GlGetVertexAttribiv:
			// Some applications iterate over all arrays and query their state.
			// This may fail if the target supports fewer arrays than the capture.
			// As these should have no side-effects, just drop them.
			return

		case *GlShaderSource:
			if version.IsES { // No compat required.
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
			// Apply the state mutation of the unmodified glShaderSource
			// command.
			// This is so we can grab the source string from the Shader object.
			// We will actually provide the source to driver at compile time.
			cmd.Mutate(ctx, id, s, nil /* builder */, nil /* watcher */)
			return

		case *GlCompileShader:
			if version.IsES { // No compat required.
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
			shader := c.Objects().Shaders().Get(cmd.Shader())
			src := ""

			st, err := shader.Type().ShaderType()
			if err != nil {
				onError(ctx, id, cmd, err)
			}
			opts := shadertools.ConvertOptions{
				ShaderType:         st,
				Relaxed:            true, // find_issues will still report bad GLSL.
				StripOptimizations: true,
				TargetGLSLVersion:  version.MaxGLSL().AsInt(),
			}

			// Trim any prefix whitespace / newlines.
			// This isn't legal if it comes before the #version, but this
			// will be picked up by find_issues.go anyway.
			src = strings.TrimLeft(shader.Source(), "\n\r\t ")

			res, err := shadertools.ConvertGlsl(src, &opts)
			if err != nil {
				// Could not convert the shader.
				onError(ctx, id, cmd, err)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

			src = res.SourceCode

			tmpSrc := s.AllocDataOrPanic(ctx, src)
			tmpPtrToSrc := s.AllocDataOrPanic(ctx, tmpSrc.Ptr())
			defer tmpSrc.Free()
			defer tmpPtrToSrc.Free()
			srcCmd := cb.GlShaderSource(cmd.Shader(), 1, tmpPtrToSrc.Ptr(), memory.Nullptr).
				AddRead(tmpSrc.Data()).
				AddRead(tmpPtrToSrc.Data())
			out.MutateAndWrite(ctx, id, srcCmd)

		// TODO: glVertexAttribIPointer
		case *GlVertexAttribPointer:
			if cmd.Type() == GLenum_GL_HALF_FLOAT_OES && target.vertexHalfFloatOES == unsupported {
				// Convert GL_HALF_FLOAT_OES to GL_HALF_FLOAT_ARB.
				cmd = cb.GlVertexAttribPointer(cmd.Location(), cmd.Size(), GLenum_GL_HALF_FLOAT_ARB, cmd.Normalized(), cmd.Stride(), memory.Pointer(cmd.Data()))
			}
			vaa := c.Bound().VertexArray().VertexAttributeArrays().Get(cmd.Location())
			if target.vertexArrayObjects == required && c.Bound().ArrayBuffer().IsNil() {
				// Client-pointers are not supported, we need to copy this data to a buffer.
				// However, we can't do this now as the observation only happens at the draw call.
				clientVAs[vaa] = cmd
			} else {
				delete(clientVAs, vaa)
				out.MutateAndWrite(ctx, id, cmd)
			}
			return

		case *GlDrawBuffers:
			// Currently the default framebuffer for replay is single-buffered
			// and so we need to transform any usage of GL_BACK to GL_FRONT.
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			bufs := cmd.Bufs().Slice(0, uint64(cmd.N()), s.MemoryLayout).MustRead(ctx, cmd, s, nil)
			for i, buf := range bufs {
				if buf == GLenum_GL_BACK {
					bufs[i] = GLenum_GL_FRONT
				}
			}
			tmp := s.AllocDataOrPanic(ctx, bufs)
			defer tmp.Free()
			out.MutateAndWrite(ctx, id, cb.GlDrawBuffers(cmd.N(), tmp.Ptr()).AddRead(tmp.Data()))
			return

		case *GlDrawArrays:
			if target.vertexArrayObjects == required {
				if clientVAsBound(c, clientVAs) {
					first := uint32(cmd.FirstIndex())
					count := uint32(cmd.IndicesCount())
					t := newTweaker(out, dID, cb)
					defer t.revert(ctx)
					moveClientVBsToVAs(ctx, t, clientVAs, first, count, id, cmd, s, c, out)
				}
			}
			compatMultiviewDraw(ctx, id, cmd, out)
			return

		case drawElements:
			if target.vertexArrayObjects != required {
				compatMultiviewDraw(ctx, id, cmd, out)
			} else {
				t := newTweaker(out, dID, cb)
				defer t.revert(ctx)
				compatDrawElements(ctx, t, clientVAs, id, cmd, s, out)
			}
			return

		case *GlCompressedTexImage2D:
			if _, supported := target.compressedTextureFormats[cmd.Internalformat()]; !supported {
				if err := decompressTexImage2D(ctx, id, cmd, s, out); err == nil {
					return
				}
				onError(ctx, id, cmd, fmt.Errorf("Error decompressing texture: %v", err))
			}

		case *GlCompressedTexSubImage2D:
			if _, supported := target.compressedTextureFormats[cmd.Internalformat()]; !supported {
				if err := decompressTexSubImage2D(ctx, id, cmd, s, out); err == nil {
					return
				}
				onError(ctx, id, cmd, fmt.Errorf("Error decompressing texture: %v", err))
			}

		case *GlTexBufferEXT:
			if version.AtLeastGL(3, 1) { // Strip suffix on desktop.
				cmd := cb.GlTexBuffer(cmd.Target(), cmd.Internalformat(), cmd.Buffer())
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		// TODO: glTexStorage functions are not guaranteed to be supported. Consider replacing with glTexImage calls.
		// TODO: Handle glTextureStorage family of functions - those use direct state access, not the bound texture.
		case *GlTexStorage1DEXT:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				if !version.IsES { // Strip suffix on desktop.
					cmd := cb.GlTexStorage1D(cmd.Target(), cmd.Levels(), cmd.Internalformat(), cmd.Width())
					out.MutateAndWrite(ctx, id, cmd)
					return
				}
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexStorage2D:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexStorage2DEXT:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				if !version.IsES { // Strip suffix on desktop.
					cmd := cb.GlTexStorage2D(cmd.Target(), cmd.Levels(), cmd.Internalformat(), cmd.Width(), cmd.Height())
					out.MutateAndWrite(ctx, id, cmd)
					return
				}
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexStorage2DMultisample:
			if version.IsES || version.AtLeastGL(4, 3) {
				// glTexStorage2DMultisample is supported by replay device.
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
			} else {
				// glTexStorage2DMultisample is not supported by replay device.
				// Use glTexImage2DMultisample instead.
				cmd := cb.GlTexImage2DMultisample(cmd.Target(), cmd.Samples(), cmd.Internalformat(), cmd.Width(), cmd.Height(), cmd.Fixedsamplelocations())
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
			}
			return
		case *GlTexStorage3D:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexStorage3DEXT:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				if !version.IsES { // Strip suffix on desktop.
					cmd := cb.GlTexStorage3D(cmd.Target(), cmd.Levels(), cmd.Internalformat(), cmd.Width(), cmd.Height(), cmd.Depth())
					out.MutateAndWrite(ctx, id, cmd)
					return
				}
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexStorage3DMultisample:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexStorage3DMultisampleOES:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				if !version.IsES { // Strip suffix on desktop.
					cmd := cb.GlTexStorage3DMultisample(cmd.Target(), cmd.Samples(), cmd.Internalformat(), cmd.Width(), cmd.Height(), cmd.Depth(), cmd.Fixedsamplelocations())
					out.MutateAndWrite(ctx, id, cmd)
					return
				}
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexImage2D:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{
					func() GLenum { return GLenum(cmd.Internalformat()) },
					func(fmt GLenum) { cmd.SetInternalformat(GLint(fmt)) },
				}
				fmt := &glenumProperty{cmd.Fmt, cmd.SetFmt}
				ty := &glenumProperty{cmd.Type, cmd.SetType}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, fmt, ty, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexImage3D:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{
					func() GLenum { return GLenum(cmd.Internalformat()) },
					func(fmt GLenum) { cmd.SetInternalformat(GLint(fmt)) },
				}
				fmt := &glenumProperty{cmd.Fmt, cmd.SetFmt}
				ty := &glenumProperty{cmd.Type, cmd.SetType}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, fmt, ty, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexImage3DOES:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				fmt := &glenumProperty{cmd.Fmt, cmd.SetFmt}
				ty := &glenumProperty{cmd.Type, cmd.SetType}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, fmt, ty, out, id, cmd)
				if !version.IsES { // Strip suffix on desktop.
					extras := cmd.extras
					cmd := cb.GlTexImage3D(cmd.Target(), cmd.Level(), GLint(cmd.Internalformat()), cmd.Width(), cmd.Height(), cmd.Depth(), cmd.Border(), cmd.Fmt(), cmd.Type(), memory.Pointer(cmd.Pixels()))
					cmd.extras = extras
					out.MutateAndWrite(ctx, id, cmd)
					return
				}
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexSubImage2D:
			{
				cmd := cmd.clone(s.Arena)
				fmt := &glenumProperty{cmd.Fmt, cmd.SetFmt}
				ty := &glenumProperty{cmd.Type, cmd.SetType}
				textureCompat.convertFormat(ctx, cmd.Target(), nil, fmt, ty, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexSubImage3D:
			{
				cmd := cmd.clone(s.Arena)
				fmt := &glenumProperty{cmd.Fmt, cmd.SetFmt}
				ty := &glenumProperty{cmd.Type, cmd.SetType}
				textureCompat.convertFormat(ctx, cmd.Target(), nil, fmt, ty, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlTexSubImage3DOES:
			{
				cmd := cmd.clone(s.Arena)
				fmt := &glenumProperty{cmd.Fmt, cmd.SetFmt}
				ty := &glenumProperty{cmd.Type, cmd.SetType}
				textureCompat.convertFormat(ctx, cmd.Target(), nil, fmt, ty, out, id, cmd)
				if !version.IsES { // Strip suffix on desktop.
					extras := cmd.extras
					cmd := cb.GlTexSubImage3D(cmd.Target(), cmd.Level(), cmd.Xoffset(), cmd.Yoffset(), cmd.Zoffset(), cmd.Width(), cmd.Height(), cmd.Depth(), cmd.Fmt(), cmd.Type(), memory.Pointer(cmd.Pixels()))
					cmd.extras = extras
					out.MutateAndWrite(ctx, id, cmd)
					return
				}
				out.MutateAndWrite(ctx, id, cmd)
				return
			}
		case *GlCopyTexImage2D:
			{
				cmd := cmd.clone(s.Arena)
				internalFormat := &glenumProperty{cmd.Internalformat, cmd.SetInternalformat}
				textureCompat.convertFormat(ctx, cmd.Target(), internalFormat, nil, nil, out, id, cmd)
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		case *GlTexParameterIivOES:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Pname(), out, id, cmd)
				return
			}
		case *GlTexParameterIuivOES:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Pname(), out, id, cmd)
				return
			}
		case *GlTexParameterIiv:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Pname(), out, id, cmd)
				return
			}
		case *GlTexParameterIuiv:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Pname(), out, id, cmd)
				return
			}
		case *GlTexParameterf:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Parameter(), out, id, cmd)
				return
			}
		case *GlTexParameterfv:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Pname(), out, id, cmd)
				return
			}
		case *GlTexParameteri:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Parameter(), out, id, cmd)
				return
			}
		case *GlTexParameteriv:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Pname(), out, id, cmd)
				return
			}
		case *GlTexParameterIivEXT:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Pname(), out, id, cmd)
				return
			}
		case *GlTexParameterIuivEXT:
			{
				cmd := cmd.clone(s.Arena)
				convertTexTarget(cmd)
				out.MutateAndWrite(ctx, id, cmd)
				textureCompat.postTexParameter(ctx, cmd.Target(), cmd.Pname(), out, id, cmd)
				return
			}

		case *GlProgramBinary:
			if !canUsePrecompiledShader(c, glDev) {
				for _, cmd := range buildStubProgram(ctx, cmd.Thread(), cmd.Extras(), s, cmd.Program()) {
					t.Transform(ctx, id, cmd, out)
				}
				return
			}

		case *GlProgramBinaryOES:
			if !canUsePrecompiledShader(c, glDev) {
				for _, cmd := range buildStubProgram(ctx, cmd.Thread(), cmd.Extras(), s, cmd.Program()) {
					t.Transform(ctx, id, cmd, out)
				}
				return
			}

		case *GlHint:
			if cmd.Target() == GLenum_GL_GENERATE_MIPMAP_HINT && !target.supportGenerateMipmapHint {
				return // Not supported in the core profile of OpenGL.
			}

		case *GlDebugMessageCallback,
			*GlDebugMessageControl,
			*GlDebugMessageCallbackKHR,
			*GlDebugMessageControlKHR:
			// Ignore - the callback function address is invalid in replay.
			return

		case *GlGetBooleani_v,
			*GlGetBooleanv,
			*GlGetFloatv,
			*GlGetInteger64i_v,
			*GlGetInteger64v,
			*GlGetIntegeri_v,
			*GlGetIntegerv,
			*GlGetInternalformativ,
			*GlGetString,
			*GlGetStringi:
			// The acceptable values of these get functions vary between GL versions.
			// As these should have no side-effects, just drop them.
			return

		case *GlGetActiveAttrib,
			*GlGetActiveUniform:
			// The number of active attributes and uniforms can vary between compilers
			// depending on their ability to eliminate dead code. In particular,
			// dead code in pixel shader can allow code removal in the vertex shader.
			// As these should have no side-effects, just drop them.
			return

		case *GlGetProgramInterfaceiv:
			// Introduced as core in 4.3, but macOS caps out at 4.1.
			// As this should have no side-effects, just drop them.
			return

		case *GlLabelObjectEXT,
			*GlGetObjectLabelEXT,
			*GlObjectLabel,
			*GlObjectLabelKHR,
			*GlGetObjectLabel,
			*GlObjectPtrLabel,
			*GlGetObjectPtrLabel,
			*GlGetObjectLabelKHR:
			// These methods require non-trivial remapping for replay.
			// As they do not affect rendering output, just drop them.
			return

		case *GlInsertEventMarkerEXT,
			*GlPushGroupMarkerEXT,
			*GlPopGroupMarkerEXT,
			*GlPushDebugGroup,
			*GlPopDebugGroup,
			*GlPushDebugGroupKHR,
			*GlPopDebugGroupKHR,
			*GlDebugMessageInsertKHR:
			// Debug markers may not be supported on the replay device.
			// As they do not affect rendering output, just drop them.
			return

		case *GlGetProgramBinary,
			*GlGetProgramBinaryOES:
			// Program binaries are very driver specific. This command may fail on replay
			// because one of the arguments must be GL_PROGRAM_BINARY_LENGTH.
			// It has no side effects, so just drop it.
			return

		case *GlEnable:
			if cmd.Capability() == GLenum_GL_FRAMEBUFFER_SRGB &&
				target.framebufferSrgb == required && contexts[c].framebufferSrgb != required &&
				c.Bound().DrawFramebuffer().GetID() == 0 {
				// Ignore enabling of FRAMEBUFFER_SRGB if the capture device did not
				// support an SRGB default framebuffer, but the replay device does. This
				// is only done if the current bound draw framebuffer is the default
				// framebuffer. The state is mutated so that when a non-default
				// framebuffer is bound later on, FRAMEBUFFER_SRGB will be enabled.
				// (see GlBindFramebuffer below)
				cmd.Mutate(ctx, id, s, nil /* builder */, nil /* watcher */)
				return
			}

		case *GlDisable:
			// GL_QCOM_alpha_test adds back GL_ALPHA_TEST from GLES 1.0 as extension.
			// It seems that applications only disable it to make sure it is off, so
			// we can safely ignore it. We should not ignore glEnable for it though.
			if cmd.Capability() == GLenum_GL_ALPHA_TEST_QCOM {
				return
			}

		case *GlGetGraphicsResetStatusEXT:
			// From extension GL_EXT_robustness
			// It may not be implemented by the replay driver.
			// It has no effect on rendering so just drop it.
			return

		case *GlDiscardFramebufferEXT: // GL_EXT_discard_framebuffer
			// It may not be implemented by the replay driver.
			// It is only a hint so we can just drop it.
			// TODO: It has performance impact so we should not ignore it when profiling.
			return

		case *GlInvalidateFramebuffer, *GlInvalidateSubFramebuffer:
			if !version.AtLeastES(3, 0) || !version.AtLeastGL(4, 3) {
				return // Not supported. Only a hint. Drop it.
			}

		case *GlMapBufferOES:
			if !version.IsES { // Remove extension suffix on desktop.
				cmd := cb.GlMapBuffer(cmd.Target(), cmd.Access(), memory.Pointer(cmd.Result()))
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		case *GlMapBufferRangeEXT:
			if !version.IsES { // Remove extension suffix on desktop.
				cmd := cb.GlMapBufferRange(cmd.Target(), cmd.Offset(), cmd.Length(), cmd.Access(), memory.Pointer(cmd.Result()))
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		case *GlFlushMappedBufferRangeEXT:
			if !version.IsES { // Remove extension suffix on desktop.
				extras := cmd.extras
				cmd := cb.GlFlushMappedBufferRange(cmd.Target(), cmd.Offset(), cmd.Length())
				cmd.extras = extras
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		case *GlUnmapBufferOES:
			if !version.IsES { // Remove extension suffix on desktop.
				extras := cmd.extras
				cmd := cb.GlUnmapBuffer(cmd.Target(), cmd.Result())
				cmd.extras = extras
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		case *GlDeleteBuffers:
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			ids, err := cmd.Buffers().Slice(0, uint64(cmd.Count()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				deleteCompat(ctx, ids, dID, dictionary.From(c.Objects().Buffers()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteBuffers(cnt, buf) })
				return
			}

		case *GlDeleteFramebuffers:
			// If you delete a framebuffer that is currently bound then the
			// binding automatically reverts back to the default framebuffer
			// (0). As we do compat for glBindFramebuffer(), scan the list of
			// framebuffers that are being deleted, and forward them to a fake
			// call to glBindFramebuffer(XXX, 0) if we find any.
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			fbs, err := cmd.Framebuffers().Slice(0, uint64(cmd.Count()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				for _, fb := range fbs {
					if fb == c.Bound().DrawFramebuffer().ID() {
						t.Transform(ctx, dID, cb.GlBindFramebuffer(GLenum_GL_DRAW_FRAMEBUFFER, 0), out)
					}
					if fb == c.Bound().ReadFramebuffer().ID() {
						t.Transform(ctx, dID, cb.GlBindFramebuffer(GLenum_GL_READ_FRAMEBUFFER, 0), out)
					}
				}

				deleteCompat(ctx, fbs, dID, dictionary.From(c.Objects().Framebuffers()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteFramebuffers(cnt, buf) })
				return
			}

		case *GlDeleteProgramPipelines:
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			ids, err := cmd.Pipelines().Slice(0, uint64(cmd.N()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				deleteCompat(ctx, ids, dID, dictionary.From(c.Objects().Pipelines()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteProgramPipelines(cnt, buf) })
				return
			}

		case *GlDeleteQueries:
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			ids, err := cmd.Queries().Slice(0, uint64(cmd.Count()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				deleteCompat(ctx, ids, dID, dictionary.From(c.Objects().Queries()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteQueries(cnt, buf) })
				return
			}

		case *GlDeleteRenderbuffers:
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			ids, err := cmd.Renderbuffers().Slice(0, uint64(cmd.Count()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				deleteCompat(ctx, ids, dID, dictionary.From(c.Objects().Renderbuffers()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteRenderbuffers(cnt, buf) })
				return
			}

		case *GlDeleteSamplers:
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			ids, err := cmd.Samplers().Slice(0, uint64(cmd.Count()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				deleteCompat(ctx, ids, dID, dictionary.From(c.Objects().Samplers()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteSamplers(cnt, buf) })
				return
			}

		case *GlDeleteTextures:
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			ids, err := cmd.Textures().Slice(0, uint64(cmd.Count()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				deleteCompat(ctx, ids, dID, dictionary.From(c.Objects().Textures()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteTextures(cnt, buf) })
				return
			}

		case *GlDeleteTransformFeedbacks:
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			ids, err := cmd.Ids().Slice(0, uint64(cmd.Count()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				deleteCompat(ctx, ids, dID, dictionary.From(c.Objects().TransformFeedbacks()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteTransformFeedbacks(cnt, buf) })
				return
			}

		case *GlDeleteVertexArrays:
			cmd.Extras().Observations().ApplyReads(s.Memory.ApplicationPool())
			ids, err := cmd.Arrays().Slice(0, uint64(cmd.Count()), s.MemoryLayout).Read(ctx, cmd, s, nil)
			if err == nil {
				deleteCompat(ctx, ids, dID, dictionary.From(c.Objects().VertexArrays()), s, out,
					func(cnt GLsizei, buf memory.Pointer) api.Cmd { return cb.GlDeleteVertexArrays(cnt, buf) })
				return
			}

		case *GlBindFramebuffer:
			if cmd.Framebuffer() != 0 && !c.Objects().GeneratedNames().Framebuffers().Get(cmd.Framebuffer()) {
				// glGenFramebuffers() was not used to generate the buffer. Legal in GLES.
				tmp := s.AllocDataOrPanic(ctx, cmd.Framebuffer())
				defer tmp.Free()
				out.MutateAndWrite(ctx, dID, cb.GlGenFramebuffers(1, tmp.Ptr()).AddRead(tmp.Data()))
			}

			if target.framebufferSrgb == required && contexts[c].framebufferSrgb != required &&
				c.Pixel().FramebufferSrgb() != 0 {
				// Replay device defaults FRAMEBUFFER_SRGB to disabled and allows
				// enabling it (desktop), while the capture device defaulted to enabled
				// and may or may not have allowed it to be changed (GLES). While at the
				// same time, we currently assume that the default frame buffer is not
				// SRGB capable. Thus, when SRGB is enabled in the state, and we're
				// binding the default framebuffer, SRGB needs to be disabled, and
				// specifically enabled when binding the non-default framebuffer.
				// (If it was explicitly disabled in the capture, no change is needed.)
				// TODO: Handle the use of the EGL KHR_gl_colorspace extension.
				if cmd.Target() == GLenum_GL_FRAMEBUFFER || cmd.Target() == GLenum_GL_DRAW_FRAMEBUFFER {
					origSrgb := c.Pixel().FramebufferSrgb()
					if cmd.Framebuffer() == 0 {
						out.MutateAndWrite(ctx, dID, cb.GlDisable(GLenum_GL_FRAMEBUFFER_SRGB))
					} else {
						out.MutateAndWrite(ctx, dID, cb.GlEnable(GLenum_GL_FRAMEBUFFER_SRGB))
					}
					// Change the replay driver state, but keep our mutated state,
					// so we know what to do the next time we see glBindFramebuffer.
					// TODO: Handle SRGB better.
					c.Pixel().SetFramebufferSrgb(origSrgb)
				}
			}

		case *EglDestroyContext:
			// Removing the context would interfere with the EGLImage compat below,
			// since TextureID remapping relies on being able to find the Context by ID.
			return

		case *GlEGLImageTargetTexture2DOES:
			{
				eglImage := GetState(s).EGLImages().Get(EGLImageKHR(cmd.Image()))
				if eglImage.IsNil() {
					analytics.SendBug(1498)
					onError(ctx, id, cmd, fmt.Errorf("Encountered nil eglImage. Replay may be corrupt. See: https://github.com/google/gapid/issues/1498"))
					out.MutateAndWrite(ctx, id, cmd)
					return
				}

				t := newTweaker(out, dID, cb)
				t.GlBindBuffer_PixelUnpackBuffer(ctx, 0)

				imgs := eglImage.Images()
				img := imgs.Get(0)
				sizedFormat := img.SizedFormat() // Might be RGB565 which is not supported on desktop
				sizedFormatProp := &glenumProperty{func() GLenum { return sizedFormat }, func(f GLenum) { sizedFormat = f }}

				if target.eglImageExternal == unsupported {
					target := cmd.Target()

					switch target {
					case GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_EXTERNAL_OES:
						// First time this texture is sync'ed. Initilize it.
						if c.Bound().TextureUnit().Binding2d().Image().IsNil() {
							textureCompat.convertFormat(ctx, GLenum_GL_TEXTURE_2D, sizedFormatProp, nil, nil, out, id, cmd)
							out.MutateAndWrite(ctx, dID, cb.GlTexImage2D(GLenum_GL_TEXTURE_2D, 0, GLint(sizedFormat), img.Width(), img.Height(), 0, img.DataFormat(), img.DataType(), memory.Nullptr))
							// External textures use GL_LINEAR as the default and only allow GL_LINEAR or GL_NEAREST.
							if c.Bound().TextureUnit().Binding2d().MinFilter() == GLenum_GL_NEAREST_MIPMAP_LINEAR {
								out.MutateAndWrite(ctx, dID, cb.GlTexParameteri(GLenum_GL_TEXTURE_2D, GLenum_GL_TEXTURE_MIN_FILTER, GLint(GLenum_GL_LINEAR)))
							}
						}
					case GLenum_GL_TEXTURE_2D_ARRAY:
						// First time this texture is sync'ed. Initilize it.
						if c.Bound().TextureUnit().Binding2dArray().Image().IsNil() {
							textureCompat.convertFormat(ctx, GLenum_GL_TEXTURE_2D_ARRAY, sizedFormatProp, nil, nil, out, id, cmd)
							out.MutateAndWrite(ctx, dID, cb.GlTexImage3D(GLenum_GL_TEXTURE_2D_ARRAY, 0, GLint(sizedFormat), img.Width(), img.Height(), GLsizei(imgs.Len()), 0, img.DataFormat(), img.DataType(), memory.Nullptr))
							// External textures use GL_LINEAR as the default and only allow GL_LINEAR or GL_NEAREST.
							if c.Bound().TextureUnit().Binding2dArray().MinFilter() == GLenum_GL_NEAREST_MIPMAP_LINEAR {
								out.MutateAndWrite(ctx, dID, cb.GlTexParameteri(GLenum_GL_TEXTURE_2D_ARRAY, GLenum_GL_TEXTURE_MIN_FILTER, GLint(GLenum_GL_LINEAR)))
							}
						}
					default:
						onError(ctx, id, cmd, fmt.Errorf("Unexpected GlEGLImageTargetTexture2DOES target: %v", target))
					}
				} else {
					switch eglImage.Target() {
					case EGLenum_EGL_GL_TEXTURE_2D:
						// Already a texture backed external image.
					case EGLenum_EGL_NATIVE_BUFFER_ANDROID:
						// Create a new texture and create the external image based on it instead.
						texID := newTexture(id, cb, out)
						t.glBindTexture_2D(ctx, texID)
						textureCompat.convertFormat(ctx, GLenum_GL_TEXTURE_2D, sizedFormatProp, nil, nil, out, id, cmd)
						out.MutateAndWrite(ctx, dID, cb.GlTexImage2D(GLenum_GL_TEXTURE_2D, 0, GLint(sizedFormat), img.Width(), img.Height(), 0, img.DataFormat(), img.DataType(), memory.Nullptr))
						// The mutate here will change the EGLImage to now be backed by our texture.
						// We can pass null pointers for most arguments, as they are ignored in the
						// custom replay.
						out.MutateAndWrite(ctx, dID, cb.EglCreateImageKHR(memory.Nullptr, eglContextHandle[c], EGLenum_EGL_GL_TEXTURE_2D, EGLClientBuffer(texID), memory.Nullptr, cmd.Image()))
					default:
						onError(ctx, id, cmd, fmt.Errorf("Unexpected eglCreateImageKHR target: %v", cmd.Target()))
					}
				}

				// Update the content if we made a snapshot.
				if e := FindEGLImageData(cmd.Extras()); e != nil {
					t.setUnpackStorage(ctx, NewPixelStorageState(s.Arena,
						0, // ImageHeight
						0, // SkipImages
						0, // RowLength
						0, // SkipRows
						0, // SkipPixels
						1, // Alignment
					), 0)
					if target.eglImageExternal != unsupported && eglImage.Target() == EGLenum_EGL_GL_TEXTURE_2D {
						// Update the actual underlying texture of the eglImage.
						t.eglMakeCurrent(ctx, eglImage.Context())
						t.glBindTexture_2D(ctx, TextureId(eglImage.Buffer().Address()))
					}

					ptr := s.AllocOrPanic(ctx, e.Size)
					out.MutateAndWrite(ctx, dID, cb.GlTexSubImage2D(GLenum_GL_TEXTURE_2D, 0, 0, 0, e.Width, e.Height, e.Format, e.Type, ptr.Ptr()).AddRead(ptr.Range(), e.ID))
					ptr.Free()
				}

				// The revert is needed before we replay the command to restore
				// the correct context and texture bindings.
				t.revert(ctx)
				if target.eglImageExternal != unsupported {
					out.MutateAndWrite(ctx, id, cmd)
				}
				return
			}

		// EXT_multisampled_render_to_texture
		case *GlRenderbufferStorageMultisampleEXT:
			{
				// TODO: Support multi-sample rendering.
				cmd := cb.GlRenderbufferStorage(cmd.Target(), cmd.Internalformat(), cmd.Width(), cmd.Height())
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		// EXT_multisampled_render_to_texture
		case *GlFramebufferTexture2DMultisampleEXT:
			{
				// TODO: Support multi-sample rendering.
				cmd := cb.GlFramebufferTexture2D(cmd.Target(), cmd.Attachment(), cmd.Textarget(), cmd.Texture(), cmd.Level())
				out.MutateAndWrite(ctx, id, cmd)
				return
			}

		case *GlFramebufferTextureMultiviewOVR:
			{
				cmd.Mutate(ctx, id, s, nil /* builder */, nil /* watcher */)
				// Translate it to the non-multiview version, but do not modify state,
				// otherwise we would lose the knowledge about view count.
				out.MutateAndWrite(ctx, dID, cb.Custom(func(ctx context.Context, s *api.GlobalState, b *builder.Builder) error {
					cb.GlFramebufferTextureLayer(cmd.Target(), cmd.Attachment(), cmd.Texture(), cmd.Level(), cmd.BaseViewIndex()).Call(ctx, s, b)
					return nil
				}))
				return
			}

		case *GlFramebufferTextureMultisampleMultiviewOVR:
			{
				// TODO: Support multi-sample rendering.
				cmd.Mutate(ctx, id, s, nil /* builder */, nil /* watcher */)
				// Translate it to the non-multiview version, but do not modify state,
				// otherwise we would lose the knowledge about view count.
				out.MutateAndWrite(ctx, dID, cb.Custom(func(ctx context.Context, s *api.GlobalState, b *builder.Builder) error {
					cb.GlFramebufferTextureLayer(cmd.Target(), cmd.Attachment(), cmd.Texture(), cmd.Level(), cmd.BaseViewIndex()).Call(ctx, s, b)
					return nil
				}))
				return
			}

		case *GlLinkProgram:
			{
				out.MutateAndWrite(ctx, id, cmd)
				// Forcefully get all uniform locations, so that we can remap for applications that
				// just assume locations (in particular, apps tend to assume arrays are consecutive)
				// TODO: We should warn the developers that the consecutive layout is not guaranteed.
				prog := c.Objects().Programs().Get(cmd.Program())
				if res := prog.ActiveResources(); !res.IsNil() {
					for _, uniformIndex := range res.DefaultUniformBlock().Keys() {
						uniform := res.DefaultUniformBlock().Get(uniformIndex)
						baseName := strings.TrimSuffix(uniform.Name(), "[0]")
						for i := uint32(0); i < uint32(uniform.ArraySize()); i++ {
							name := baseName
							if i != 0 {
								name = fmt.Sprintf("%v[%v]", name, i)
							}
							loc := UniformLocation(uniform.Locations().Get(i))
							tmp := s.AllocDataOrPanic(ctx, name)
							defer tmp.Free()
							cmd := cb.GlGetUniformLocation(cmd.Program(), tmp.Ptr(), loc).
								AddRead(tmp.Data())
							out.MutateAndWrite(ctx, dID, cmd)
						}
					}
				}
				return
			}

		case *GlStartTilingQCOM, *GlEndTilingQCOM,
			*EglCreateNativeClientBufferANDROID:
			if !version.IsES {
				// This extension is not applicable on desktop.
				return
			}

		default:
			flags := cmd.CmdFlags(ctx, id, s)
			if flags.IsClear() {
				compatMultiviewDraw(ctx, id, cmd, out)
				return
			}
			if flags.IsDrawCall() {
				if clientVAsBound(c, clientVAs) {
					onError(ctx, id, cmd, fmt.Errorf("Draw call with client-pointers not handled by the compatability layer. Command: %v", cmd))
				}
				compatMultiviewDraw(ctx, id, cmd, out)
				return
			}
		}

		out.MutateAndWrite(ctx, id, cmd)
	})

	return t, nil
}

// Naive multiview implementation - invoke each draw call several times with different layers
func compatMultiviewDraw(ctx context.Context, id api.CmdID, cmd api.Cmd, out transform.Writer) {
	s := out.State()
	c := GetContext(s, cmd.Thread())
	dID := id.Derived()
	cb := CommandBuilder{Thread: cmd.Thread(), Arena: s.Arena}
	numViews := uint32(1)
	c.Bound().DrawFramebuffer().ForEachAttachment(func(name GLenum, att FramebufferAttachment) {
		numViews = u32.Max(numViews, uint32(att.NumViews()))
	})
	if numViews > 1 {
		for viewID := GLuint(0); viewID < GLuint(numViews); viewID++ {
			// Set the magic uniform which shaders use to fetch view-dependent attributes.
			// It is missing from the observed extras, so normal mutation would fail.
			out.MutateAndWrite(ctx, dID, cb.Custom(func(ctx context.Context, s *api.GlobalState, b *builder.Builder) error {
				if !c.Bound().Program().IsNil() {
					viewIDLocation := UniformLocation(0x7FFF0000)
					tmp := s.AllocDataOrPanic(ctx, "gapid_gl_ViewID_OVR")
					defer tmp.Free()
					cb.GlGetUniformLocation(c.Bound().Program().ID(), tmp.Ptr(), viewIDLocation).
						AddRead(tmp.Data()).
						Call(ctx, s, b)
					cb.GlUniform1ui(viewIDLocation, viewID).Call(ctx, s, b)
				}
				return nil
			}))

			// For each attachment, bind the layer corresponding to this ViewID.
			// Do not modify the state so that we do not revert to single-view for next draw call.
			c.Bound().DrawFramebuffer().ForEachAttachment(func(name GLenum, a FramebufferAttachment) {
				out.MutateAndWrite(ctx, dID, cb.Custom(func(ctx context.Context, s *api.GlobalState, b *builder.Builder) error {
					if !a.Texture().IsNil() {
						cb.GlFramebufferTextureLayer(GLenum_GL_DRAW_FRAMEBUFFER, name, a.Texture().ID(), a.TextureLevel(), a.TextureLayer()+GLint(viewID)).Call(ctx, s, b)
					}
					return nil
				}))
			})
			out.MutateAndWrite(ctx, id, cmd)
		}
	} else {
		out.MutateAndWrite(ctx, id, cmd)
	}
}

func (fb Framebufferʳ) ForEachAttachment(action func(GLenum, FramebufferAttachment)) {
	for i, a := range fb.ColorAttachments().All() {
		action(GLenum_GL_COLOR_ATTACHMENT0+GLenum(i), a)
	}
	action(GLenum_GL_DEPTH_ATTACHMENT, fb.DepthAttachment())
	action(GLenum_GL_STENCIL_ATTACHMENT, fb.StencilAttachment())
}

// canUsePrecompiledShader returns true if precompiled shaders / programs
// captured with the context c can be replayed on the device d.
func canUsePrecompiledShader(c Contextʳ, d *device.OpenGLDriver) bool {
	return c.Constants().Vendor() == d.Vendor && c.Constants().Version() == d.Version
}

// disableUnusedAttribArrays disables all vertex attribute arrays that are not
// used by the currently bound program. This is a compatibility fix for devices
// that will error with GL_INVALID_OPERATION if there's an enabled (but unused)
// vertex attribute array that has no array data when drawing. AFAICT, this
// particular behavior is undefined according to the spec.
func disableUnusedAttribArrays(ctx context.Context, t *tweaker) {
	p := t.c.Bound().Program()
	if p.IsNil() || p.ActiveResources().IsNil() {
		return
	}
	inputs := p.ActiveResources().ProgramInputs()
	used := make([]bool, t.c.Constants().MaxVertexAttribBindings())
	for _, input := range inputs.All() {
		for _, l := range input.Locations().All() {
			if l >= 0 && l < GLint(len(used)) {
				used[l] = true
			}
		}
	}

	for l, arr := range t.c.Bound().VertexArray().VertexAttributeArrays().All() {
		if arr.Enabled() == GLboolean_GL_TRUE && l < AttributeLocation(len(used)) && !used[l] {
			t.glDisableVertexAttribArray(ctx, l)
		}
	}
}

// It is a no-op to delete objects that do not exist.
// GAPID uses a shared context for replay - while its fine to delete ids that do
// not exist in this context, they might exist in another. Strip out any ids
// that do not belong to this context.
func deleteCompat(
	ctx context.Context,
	ids interface{},
	id api.CmdID,
	d dictionary.I,
	s *api.GlobalState,
	out transform.Writer,
	create func(GLsizei, memory.Pointer) api.Cmd) {

	r := reflect.ValueOf(ids)
	count := r.Len()
	zero := reflect.Zero(r.Type().Elem())
	for i := 0; i < count; i++ {
		id := r.Index(i).Interface()
		if !d.Contains(id) {
			r.Index(i).Set(zero) // Deleting 0 is also a no-op.
		}
	}

	tmp := s.AllocDataOrPanic(ctx, ids)
	defer tmp.Free()
	cmd := create(GLsizei(count), tmp.Ptr())
	cmd.Extras().GetOrAppendObservations().AddRead(tmp.Data())
	out.MutateAndWrite(ctx, id, cmd)
}