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opengl.go
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opengl.go
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// Copyright © 2013-2018 Galvanized Logic Inc.
// Use is governed by a BSD-style license found in the LICENSE file.
package render
import (
"fmt"
"image"
"log"
"strings"
"github.com/gazed/vu/render/gl"
)
// opengl is the OpenGL implementation of Renderer. See the Renderer interface
// for comments. See the OpenGL documentation for OpenGL methods and constants.
type opengl struct {
depthTest bool // Track current depth setting to reduce state switching.
shader uint32 // Track the current shader to reduce shader switching.
fbo uint32 // Track current framebuffer object to reduce switching.
vw, vh int32 // Remember the viewport size for framebuffer switching.
}
// newRenderer returns an OpenGL Context.
func newRenderer() Context { return &opengl{} }
// Renderer implementation specific constants.
const (
// Values useed in Renderer.Enable() method.
Blend uint32 = gl.BLEND // Alpha blending.
CullFace = gl.CULL_FACE // Backface culling.
DepthTest = gl.DEPTH_TEST // Z-buffer (depth) awareness.
PointSize = gl.PROGRAM_POINT_SIZE // Enable gl_PointSize in shaders.
// Vertex data render hints. Used in the Buffer.SetUsage() method.
StaticDraw = gl.STATIC_DRAW // Data created once and rendered many times.
DynamicDraw = gl.DYNAMIC_DRAW // Data is continually being updated.
)
// Renderer implementation.
func (gc *opengl) Init() error {
gl.Init()
return gc.validate()
}
// Renderer implementation.
func (gc *opengl) Color(r, g, b, a float32) { gl.ClearColor(r, g, b, a) }
func (gc *opengl) Clear() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
}
func (gc *opengl) Viewport(width int, height int) {
gc.vw, gc.vh = int32(width), int32(height)
gl.Viewport(0, 0, int32(width), int32(height))
}
// Renderer implementation.
func (gc *opengl) Enable(attribute uint32, enabled bool) {
switch attribute {
case CullFace, DepthTest:
if enabled {
gl.Enable(attribute)
} else {
gl.Disable(attribute)
}
case Blend:
if enabled {
gl.Enable(attribute)
// Using non pre-multiplied alpha color data so...
gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
} else {
gl.Disable(attribute)
}
}
}
// Render implementation.
// FUTURE: all kinds of possible optimizations that would need to be
// profiled before implementing.
// • group by vao to avoid switching vao's.
// • group by texture to avoid switching textures.
// • use interleaved vertex data.
// • only rebind uniforms when they have changed.
// • uniform buffers http://www.opengl.org/wiki/Uniform_Buffer_Object.
// • ... lots more possibilities... leave your fav here.
func (gc *opengl) Render(d *Draw) {
if d.Scissor {
gl.Enable(gl.SCISSOR_TEST) // Each scissor draw needs to...
gl.Scissor(d.Sx, d.Sy, d.Sw, d.Sh) // ... define its own area.
}
// switch state only if necessary.
if gc.depthTest != d.Depth {
if d.Depth {
gl.Enable(gl.DEPTH_TEST)
} else {
gl.Disable(gl.DEPTH_TEST)
}
gc.depthTest = d.Depth
}
// switch render framebuffer only if necessary. The framebuffer
// is used to render to a texture associated with a framebuffer.
if gc.fbo != d.Fbo {
gl.BindFramebuffer(gl.FRAMEBUFFER, d.Fbo)
if d.Fbo == 0 {
gl.Viewport(0, 0, gc.vw, gc.vh)
} else {
gl.Clear(gl.DEPTH_BUFFER_BIT)
gl.Viewport(0, 0, LayerSize, LayerSize) // framebuffer texture.
}
gc.fbo = d.Fbo
}
// switch shaders only if necessary.
if gc.shader != d.Shader {
gl.UseProgram(d.Shader)
gc.shader = d.Shader
}
// Ask the model to bind its provisioned uniforms.
// FUTURE: only need to bind uniforms that have changed.
gc.bindUniforms(d)
// bind the data buffers and render.
// FUTURE: support instanced for more than triangles.
gl.BindVertexArray(d.Vao)
switch d.Mode {
case Lines:
gl.PolygonMode(gl.FRONT_AND_BACK, gl.LINE)
gl.DrawElements(gl.LINES, d.FaceCnt, gl.UNSIGNED_SHORT, 0)
gl.PolygonMode(gl.FRONT_AND_BACK, gl.FILL)
case Points:
gl.Enable(gl.PROGRAM_POINT_SIZE)
gl.DrawArrays(gl.POINTS, 0, d.VertCnt)
gl.Disable(gl.PROGRAM_POINT_SIZE)
case Triangles:
if d.Instances > 0 {
gl.DrawElementsInstanced(gl.TRIANGLES, d.FaceCnt, gl.UNSIGNED_SHORT, 0, d.Instances)
} else {
gl.DrawElements(gl.TRIANGLES, d.FaceCnt, gl.UNSIGNED_SHORT, 0)
}
}
gl.BindVertexArray(0)
if d.Scissor {
gl.Disable(gl.SCISSOR_TEST)
}
}
// bindUniforms links model data to the uniforms discovered
// in the model shader.
// FUTURE: create design that incorporates special cases like
// textures and animation bone poses.
func (gc *opengl) bindUniforms(d *Draw) {
for key, ref := range d.Uniforms { // Uniforms expected by the shader.
switch {
case key == "bpos":
if d.Poses != nil && len(d.Poses) > 0 {
gl.UniformMatrix3x4fv(ref, int32(d.NumPoses), false, &(d.Poses[0]))
} else {
log.Printf("Animation data expected for %d", d.Tag)
}
case key == "sm":
gl.Uniform1i(ref, 15) // Convention for shadow maps.
gl.ActiveTexture(gl.TEXTURE0 + 15)
gl.BindTexture(gl.TEXTURE_2D, d.Shtex)
case strings.HasPrefix(key, "uv"):
// Map the texture order to the texture variable names.
index := 0
fmt.Sscanf(key, "uv%d", &index)
for _, t := range d.Texs {
if t.order == index {
gl.Uniform1i(ref, int32(t.order))
gl.ActiveTexture(gl.TEXTURE0 + uint32(t.order))
gl.BindTexture(gl.TEXTURE_2D, t.tid)
break
}
}
default:
// Everything else is uniform float or matrix data.
data, ok := d.UniformData[ref] // Uniform data set by engine and App.
if !ok {
log.Printf("No uniform data for %d %s", d.Tag, key)
continue
}
switch len(data) {
case 1:
gl.Uniform1f(ref, data[0])
case 2:
gl.Uniform2f(ref, data[0], data[1])
case 3:
gl.Uniform3f(ref, data[0], data[1], data[2])
case 4:
gl.Uniform4f(ref, data[0], data[1], data[2], data[3])
case 16:
// 4x4 matrix.
gl.UniformMatrix4fv(ref, 1, false, &(data[0]))
default:
log.Printf("Failed to bind %d %s %d", d.Tag, key, len(data))
}
}
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
log.Printf("bindUniforms %d failed %X %d %s", ref, d.Tag, glerr, key)
}
}
}
// validate that OpenGL is available at the right version.
// For OpenGL 3.2 the following lines should be in the report.
// [+] glFramebufferTexture
// [+] glGetBufferParameteri64v
// [+] glGetInteger64i_v
func (gc *opengl) validate() error {
if report := gl.BindingReport(); len(report) > 0 {
valid := false
want := "[+] glFramebufferTexture"
for _, line := range report {
if strings.Contains(line, want) {
valid = true
break
}
}
if !valid {
return fmt.Errorf("Need OpenGL 3.2 or higher")
}
} else {
return fmt.Errorf("OpenGL unavailable")
}
return nil
}
// Renderer implementation.
// BindMesh copies the given mesh data to the GPU
// and initializes the vao and buffer references.
func (gc *opengl) BindMesh(vao *uint32, vdata map[uint32]Data, fdata Data) error {
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
return fmt.Errorf("BindMesh: fix prior error %X", glerr)
}
// Reuse existing vao's.
if *vao == 0 {
gl.GenVertexArrays(1, vao)
}
gl.BindVertexArray(*vao)
for _, vbuff := range vdata {
vd, ok := vbuff.(*vertexData)
if ok && vd.rebind {
gc.bindVertexBuffer(vd)
vd.rebind = false
}
}
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
return fmt.Errorf("BindMesh failed to bind vb %X", glerr)
}
if fd, ok := fdata.(*faceData); ok {
if fd.rebind {
gc.bindFaceBuffer(fd)
fd.rebind = false
}
}
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
return fmt.Errorf("BindMesh failed to bind fb %X", glerr)
}
gl.BindVertexArray(0)
return nil
}
// bindVertexBuffer copies per-vertex data from the CPU to the GPU.
// The vao is needed only for instanced meshes.
func (gc *opengl) bindVertexBuffer(vdata Data) {
vd, ok := vdata.(*vertexData)
if !ok {
return
}
if vd.ref == 0 {
gl.GenBuffers(1, &vd.ref)
}
bytes := 4 // 4 bytes for float32 (gl.FLOAT)
switch vd.usage {
case StaticDraw:
switch {
case len(vd.floats) > 0:
gl.BindBuffer(gl.ARRAY_BUFFER, vd.ref)
gl.BufferData(gl.ARRAY_BUFFER, int64(len(vd.floats)*bytes), gl.Pointer(&(vd.floats[0])), vd.usage)
gl.VertexAttribPointer(vd.lloc, vd.span, gl.FLOAT, false, 0, 0)
if vd.instanced {
// Instanced data are 4x4 transform matricies of floats.
rowBytes := uint32(4 * 4) // 4 floats of 4 bytes each per row.
matrixBytes := int32(4 * 4 * 4) // 4 rows of 4 floats of 4 bytes.
for cnt := uint32(0); cnt < 4; cnt++ {
gl.EnableVertexAttribArray(vd.lloc + cnt)
gl.VertexAttribPointer(vd.lloc+cnt, 4, gl.FLOAT, false, matrixBytes, int64(cnt*rowBytes))
// Ensure the matrix values are the same for each vertex and
// will only be updated once the instance changes.
gl.VertexAttribDivisor(vd.lloc+cnt, 1)
}
} else {
gl.EnableVertexAttribArray(vd.lloc)
}
case len(vd.bytes) > 0:
gl.BindBuffer(gl.ARRAY_BUFFER, vd.ref)
gl.BufferData(gl.ARRAY_BUFFER, int64(len(vd.bytes)), gl.Pointer(&(vd.bytes[0])), vd.usage)
gl.VertexAttribPointer(vd.lloc, vd.span, gl.UNSIGNED_BYTE, vd.normalize, 0, 0)
gl.EnableVertexAttribArray(vd.lloc)
}
case DynamicDraw:
var null gl.Pointer // zero.
switch {
case len(vd.floats) > 0:
gl.BindBuffer(gl.ARRAY_BUFFER, vd.ref)
// Buffer orphaning, a common way to improve streaming perf. See:
// http://www.opengl.org/wiki/Buffer_Object_Streaming
gl.BufferData(gl.ARRAY_BUFFER, int64(cap(vd.floats)*bytes), null, vd.usage)
gl.BufferSubData(gl.ARRAY_BUFFER, 0, int64(len(vd.floats)*bytes), gl.Pointer(&(vd.floats[0])))
gl.VertexAttribPointer(vd.lloc, vd.span, gl.FLOAT, false, 0, 0)
gl.EnableVertexAttribArray(vd.lloc)
}
}
gl.BindBuffer(gl.ARRAY_BUFFER, 0)
}
// bindFaceBuffer copies triangle face data from the CPU to the GPU.
func (gc *opengl) bindFaceBuffer(fdata Data) {
fd := fdata.(*faceData)
if len(fd.data) > 0 {
if fd.ref == 0 {
gl.GenBuffers(1, &fd.ref)
}
gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, fd.ref)
bytes := 2 // 2 bytes for uint16 (gl.UNSIGNED_SHORT)
gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, int64(len(fd.data)*bytes), gl.Pointer(&(fd.data[0])), fd.usage)
}
}
// Renderer implementation.
// BindShader compiles the shader and makes it available to the GPU.
// It also adds the list of uniforms and vertex layout references to the
// provided maps.
func (gc *opengl) BindShader(vsh, fsh []string, uniforms map[string]int32,
layouts map[string]uint32) (program uint32, err error) {
program = gl.CreateProgram()
// compile and link the shader program.
if glerr := gl.BindProgram(program, vsh, fsh); glerr != nil {
err = fmt.Errorf("Failed to create shader program: %s", glerr)
return
}
// initialize the uniform and layout references
gl.Uniforms(program, uniforms)
gl.Layouts(program, layouts)
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
log.Printf("shader:Bind need to find and fix error %X", glerr)
}
// // Deubugging code: dumps shader uniforms once on startup.
// log.Printf("BindShader")
// for k, v := range uniforms {
// log.Printf(" uniform %s %d", k, v)
// }
return program, err
}
// Renderer implementation.
// BindTexture makes the texture available on the GPU.
func (gc *opengl) BindTexture(tid *uint32, img image.Image) (err error) {
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
log.Printf("opengl:bindTexture find and fix prior error %X", glerr)
}
if *tid == 0 {
gl.GenTextures(1, tid)
}
gl.BindTexture(gl.TEXTURE_2D, *tid)
// FUTURE: check if RGBA, or NRGBA are alpha pre-multiplied. The docs say
// yes for RGBA but the data is from PNG files which are not pre-multiplied
// and the go png Decode looks like its reading values directly.
var ptr gl.Pointer
bounds := img.Bounds()
width, height := int32(bounds.Dx()), int32(bounds.Dy())
switch imgType := img.(type) {
case *image.RGBA:
i := img.(*image.RGBA)
ptr = gl.Pointer(&(i.Pix[0]))
case *image.NRGBA:
i := img.(*image.NRGBA)
ptr = gl.Pointer(&(i.Pix[0]))
default:
return fmt.Errorf("Unsupported image format %T", imgType)
}
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, ptr)
gl.GenerateMipmap(gl.TEXTURE_2D)
gc.SetTextureMode(*tid, false) // no repeat by default.
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
err = fmt.Errorf("Failed binding texture %d\n", glerr)
}
return err
}
// SetTextureMode is used to switch to a clamped
// texture instead of a repeating texture.
func (gc *opengl) SetTextureMode(tid uint32, clamp bool) {
gl.BindTexture(gl.TEXTURE_2D, tid)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAX_LEVEL, 7)
if clamp {
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
} else {
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT)
}
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST_MIPMAP_LINEAR)
}
// BindTarget creates a framebuffer object that can be used as render
// target. The buffer has both color and depth.
// http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-14-render-to-texture
func (gc *opengl) BindTarget(fbo, tid, db *uint32) (err error) {
size := int32(LayerSize)
gl.GenFramebuffers(1, fbo)
gl.BindFramebuffer(gl.FRAMEBUFFER, *fbo)
// Create a texture specifically for the framebuffer.
gl.GenTextures(1, tid)
gl.BindTexture(gl.TEXTURE_2D, *tid)
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, size, size,
0, gl.RGBA, gl.UNSIGNED_BYTE, gl.Pointer(nil))
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
// Add a depth buffer to mimic the normal framebuffer behaviour for 3D objects.
gl.GenRenderbuffers(1, db)
gl.BindRenderbuffer(gl.RENDERBUFFER, *db)
gl.RenderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT, size, size)
gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, *db)
// Associate the texture with the framebuffer.
gl.FramebufferTexture(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, *tid, 0)
buffType := uint32(gl.COLOR_ATTACHMENT0)
gl.DrawBuffers(1, &buffType)
// Report any problems.
glerr := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
if glerr != gl.FRAMEBUFFER_COMPLETE {
return fmt.Errorf("BindFrame error %X", glerr)
}
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
err = fmt.Errorf("Failed binding framebuffer %X", glerr)
}
gl.BindFramebuffer(gl.FRAMEBUFFER, 0) // clean up by resetting to default framebuffer.
return err
}
// BindMap creates a framebuffer object with an associated texture.
// This has depth, but no color. Expected to be used for shadow maps.
// http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-16-shadow-mapping/
func (gc *opengl) BindMap(fbo, tid *uint32) (err error) {
size := int32(LayerSize)
gl.GenFramebuffers(1, fbo)
gl.BindFramebuffer(gl.FRAMEBUFFER, *fbo)
// Create a texture specifically for the framebuffer.
gl.GenTextures(1, tid)
gl.BindTexture(gl.TEXTURE_2D, *tid)
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.DEPTH_COMPONENT16, size, size,
0, gl.DEPTH_COMPONENT, gl.FLOAT, gl.Pointer(nil))
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_COMPARE_FUNC, gl.LEQUAL)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_COMPARE_MODE, gl.COMPARE_REF_TO_TEXTURE)
// Associate the texture with the framebuffer.
gl.FramebufferTexture(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, *tid, 0)
gl.DrawBuffer(gl.NONE)
// Report any problems.
glerr := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
if glerr != gl.FRAMEBUFFER_COMPLETE {
return fmt.Errorf("BindFrame error %X", glerr)
}
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
err = fmt.Errorf("Failed binding framebuffer %X", glerr)
}
gl.BindFramebuffer(gl.FRAMEBUFFER, 0) // clean up by resetting to default framebuffer.
return err
}
// Remove graphic resources.
func (gc *opengl) ReleaseMesh(vao uint32) { gl.DeleteVertexArrays(1, &vao) }
func (gc *opengl) ReleaseShader(sid uint32) { gl.DeleteProgram(sid) }
func (gc *opengl) ReleaseTexture(tid uint32) { gl.DeleteTextures(1, &tid) }
func (gc *opengl) ReleaseTarget(fbo, tid, db uint32) {
gl.DeleteFramebuffers(1, &fbo)
gl.DeleteTextures(1, &tid)
gl.DeleteRenderbuffers(1, &db)
}
func (gc *opengl) ReleaseMap(fbo, tid uint32) {
gl.DeleteFramebuffers(1, &fbo)
gl.DeleteTextures(1, &tid)
}