forked from tfriedel6/canvas
/
shader.go
202 lines (175 loc) · 5.06 KB
/
shader.go
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package goglbackend
import (
"errors"
"fmt"
"reflect"
"strings"
"unicode"
"unicode/utf8"
"github.com/go-gl/gl/v3.2-core/gl"
)
type shaderProgram struct {
ID, vs, fs uint32
attribs map[string]uint32
uniforms map[string]int32
}
func loadShader(vs, fs string, sp *shaderProgram) error {
glError() // clear the current error
// compile vertex shader
{
sp.vs = gl.CreateShader(gl.VERTEX_SHADER)
csrc, freeFunc := gl.Strs(vs + "\x00")
defer freeFunc()
gl.ShaderSource(sp.vs, 1, csrc, nil)
gl.CompileShader(sp.vs)
var status int32
gl.GetShaderiv(sp.vs, gl.COMPILE_STATUS, &status)
if status != gl.TRUE {
var buf [65536]byte
var length int32
gl.GetShaderInfoLog(sp.vs, int32(len(buf)), &length, &buf[0])
clog := string(buf[:length])
gl.DeleteShader(sp.vs)
return fmt.Errorf("failed to compile vertex shader:\n\n%s", clog)
}
if err := glError(); err != nil {
return fmt.Errorf("gl error after compiling vertex shader: %v", err)
}
}
// compile fragment shader
{
sp.fs = gl.CreateShader(gl.FRAGMENT_SHADER)
csrc, freeFunc := gl.Strs(fs + "\x00")
defer freeFunc()
gl.ShaderSource(sp.fs, 1, csrc, nil)
gl.CompileShader(sp.fs)
var status int32
gl.GetShaderiv(sp.fs, gl.COMPILE_STATUS, &status)
if status != gl.TRUE {
var buf [65536]byte
var length int32
gl.GetShaderInfoLog(sp.fs, int32(len(buf)), &length, &buf[0])
clog := string(buf[:length])
gl.DeleteShader(sp.fs)
return fmt.Errorf("failed to compile fragment shader:\n\n%s", clog)
}
if err := glError(); err != nil {
return fmt.Errorf("gl error after compiling fragment shader: %v", err)
}
}
// link shader program
{
sp.ID = gl.CreateProgram()
gl.AttachShader(sp.ID, sp.vs)
gl.AttachShader(sp.ID, sp.fs)
gl.LinkProgram(sp.ID)
var status int32
gl.GetProgramiv(sp.ID, gl.LINK_STATUS, &status)
if status != gl.TRUE {
var buf [65536]byte
var length int32
gl.GetProgramInfoLog(sp.ID, int32(len(buf)), &length, &buf[0])
clog := string(buf[:length])
gl.DeleteProgram(sp.ID)
gl.DeleteShader(sp.vs)
gl.DeleteShader(sp.fs)
return fmt.Errorf("failed to link shader program:\n\n%s", clog)
}
if err := glError(); err != nil {
return fmt.Errorf("gl error after linking shader: %v", err)
}
}
gl.UseProgram(sp.ID)
var nameBuf [256]byte
var length, size int32
var xtype uint32
var count int32
// load the attributes
gl.GetProgramiv(sp.ID, gl.ACTIVE_ATTRIBUTES, &count)
sp.attribs = make(map[string]uint32, int(count))
for i := int32(0); i < count; i++ {
gl.GetActiveAttrib(sp.ID, uint32(i), int32(len(nameBuf)), &length, &size, &xtype, &nameBuf[0])
name := string(nameBuf[:length])
loc := gl.GetAttribLocation(sp.ID, &nameBuf[0])
sp.attribs[name] = uint32(loc)
}
// load the uniforms
gl.GetProgramiv(sp.ID, gl.ACTIVE_UNIFORMS, &count)
sp.uniforms = make(map[string]int32, int(count))
for i := int32(0); i < count; i++ {
gl.GetActiveUniform(sp.ID, uint32(i), int32(len(nameBuf)), &length, &size, &xtype, &nameBuf[0])
name := string(nameBuf[:length])
loc := gl.GetUniformLocation(sp.ID, &nameBuf[0])
sp.uniforms[name] = loc
}
return nil
}
func (sp *shaderProgram) use() {
gl.UseProgram(sp.ID)
}
func (sp *shaderProgram) delete() {
gl.DeleteProgram(sp.ID)
gl.DeleteShader(sp.vs)
gl.DeleteShader(sp.fs)
}
func (sp *shaderProgram) loadLocations(target interface{}) error {
val := reflect.ValueOf(target)
if val.Kind() != reflect.Ptr {
panic("target must be a pointer to a struct")
}
val = val.Elem()
if val.Kind() != reflect.Struct {
panic("target must be a pointer to a struct")
}
gl.UseProgram(sp.ID)
var errs strings.Builder
for name, loc := range sp.attribs {
field := val.FieldByName(sp.structName(name))
if field == (reflect.Value{}) {
fmt.Fprintf(&errs, "field for attribute \"%s\" not found; ", name)
} else if field.Type() != reflect.TypeOf(uint32(0)) {
fmt.Fprintf(&errs, "field for attribute \"%s\" must have type uint32; ", name)
} else {
field.Set(reflect.ValueOf(uint32(loc)))
}
}
for name, loc := range sp.uniforms {
field := val.FieldByName(sp.structName(name))
if field == (reflect.Value{}) {
fmt.Fprintf(&errs, "field for uniform \"%s\" not found; ", name)
} else if field.Type() != reflect.TypeOf(int32(0)) {
fmt.Fprintf(&errs, "field for uniform \"%s\" must have type int32; ", name)
} else {
field.Set(reflect.ValueOf(int32(loc)))
}
}
if errs.Len() > 0 {
return errors.New(strings.TrimSpace(errs.String()))
}
return nil
}
func (sp *shaderProgram) structName(name string) string {
rn, sz := utf8.DecodeRuneInString(name)
name = fmt.Sprintf("%c%s", unicode.ToUpper(rn), name[sz:])
idx := strings.IndexByte(name, '[')
if idx > 0 {
name = name[:idx]
}
return name
}
func (sp *shaderProgram) mustLoadLocations(target interface{}) {
err := sp.loadLocations(target)
if err != nil {
panic(err)
}
}
func (sp *shaderProgram) enableAllVertexAttribArrays() {
for _, loc := range sp.attribs {
gl.EnableVertexAttribArray(loc)
}
}
func (sp *shaderProgram) disableAllVertexAttribArrays() {
for _, loc := range sp.attribs {
gl.DisableVertexAttribArray(loc)
}
}