go-opengl-pixel/pixelgl/shader.go

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package pixelgl
import (
"fmt"
"runtime"
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"github.com/go-gl/gl/v3.3-core/gl"
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"github.com/go-gl/mathgl/mgl32"
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)
// Shader is an OpenGL shader program.
type Shader struct {
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program binder
vertexFmt AttrFormat
uniformFmt AttrFormat
uniforms map[string]int32
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}
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// NewShader creates a new shader program from the specified vertex shader and fragment shader
// sources.
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//
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// Note that vertexShader and fragmentShader parameters must contain the source code, they're
// not filenames.
func NewShader(vertexFmt, uniformFmt AttrFormat, vertexShader, fragmentShader string) (*Shader, error) {
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shader := &Shader{
program: binder{
restoreLoc: gl.CURRENT_PROGRAM,
bindFunc: func(obj uint32) {
gl.UseProgram(obj)
},
},
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vertexFmt: vertexFmt,
uniformFmt: uniformFmt,
uniforms: make(map[string]int32),
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}
var vshader, fshader uint32
// vertex shader
{
vshader = gl.CreateShader(gl.VERTEX_SHADER)
src, free := gl.Strs(vertexShader)
defer free()
length := int32(len(vertexShader))
gl.ShaderSource(vshader, 1, src, &length)
gl.CompileShader(vshader)
var (
success int32
infoLog = make([]byte, 512)
)
gl.GetShaderiv(vshader, gl.COMPILE_STATUS, &success)
if success == 0 {
gl.GetShaderInfoLog(vshader, int32(len(infoLog)), nil, &infoLog[0])
return nil, fmt.Errorf("error compiling vertex shader: %s", string(infoLog))
}
defer gl.DeleteShader(vshader)
}
// fragment shader
{
fshader = gl.CreateShader(gl.FRAGMENT_SHADER)
src, free := gl.Strs(fragmentShader)
defer free()
length := int32(len(fragmentShader))
gl.ShaderSource(fshader, 1, src, &length)
gl.CompileShader(fshader)
var (
success int32
infoLog = make([]byte, 512)
)
gl.GetShaderiv(fshader, gl.COMPILE_STATUS, &success)
if success == 0 {
gl.GetShaderInfoLog(fshader, int32(len(infoLog)), nil, &infoLog[0])
return nil, fmt.Errorf("error compiling fragment shader: %s", string(infoLog))
}
defer gl.DeleteShader(fshader)
}
// shader program
{
shader.program.obj = gl.CreateProgram()
gl.AttachShader(shader.program.obj, vshader)
gl.AttachShader(shader.program.obj, fshader)
gl.LinkProgram(shader.program.obj)
var (
success int32
infoLog = make([]byte, 512)
)
gl.GetProgramiv(shader.program.obj, gl.LINK_STATUS, &success)
if success == 0 {
gl.GetProgramInfoLog(shader.program.obj, int32(len(infoLog)), nil, &infoLog[0])
return nil, fmt.Errorf("error linking shader program: %s", string(infoLog))
}
}
// uniforms
for name := range uniformFmt {
loc := gl.GetUniformLocation(shader.program.obj, gl.Str(name+"\x00"))
shader.uniforms[name] = loc
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}
runtime.SetFinalizer(shader, (*Shader).delete)
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return shader, nil
}
func (s *Shader) delete() {
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DoNoBlock(func() {
gl.DeleteProgram(s.program.obj)
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})
}
// ID returns an OpenGL identifier of a shader program.
func (s *Shader) ID() uint32 {
return s.program.obj
}
// VertexFormat returns the vertex attribute format of this shader. Do not change it.
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func (s *Shader) VertexFormat() AttrFormat {
return s.vertexFmt
}
// UniformFormat returns the uniform attribute format of this shader. Do not change it.
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func (s *Shader) UniformFormat() AttrFormat {
return s.uniformFmt
}
// SetUniformAttr sets the value of a uniform attribute of a shader.
//
// If the attribute does not exist, this method returns false.
//
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// Supplied value must correspond to the type of the attribute. Correct types are these
// (right-hand is the type of the value):
// Attr{Type: Int}: int32
// Attr{Type: Float}: float32
// Attr{Type: Vec2}: mgl32.Vec2
// Attr{Type: Vec3}: mgl32.Vec3
// Attr{Type: Vec4}: mgl32.Vec4
// Attr{Type: Mat2}: mgl32.Mat2
// Attr{Type: Mat23}: mgl32.Mat2x3
// Attr{Type: Mat24}: mgl32.Mat2x4
// Attr{Type: Mat3}: mgl32.Mat3
// Attr{Type: Mat32}: mgl32.Mat3x2
// Attr{Type: Mat34}: mgl32.Mat3x4
// Attr{Type: Mat4}: mgl32.Mat4
// Attr{Type: Mat42}: mgl32.Mat4x2
// Attr{Type: Mat43}: mgl32.Mat4x3
// No other types are supported.
//
// The shader must be bound before calling this method.
func (s *Shader) SetUniformAttr(attr Attr, value interface{}) (ok bool) {
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if !s.uniformFmt.Contains(attr) {
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return false
}
switch attr.Type {
case Int:
value := value.(int32)
gl.Uniform1iv(s.uniforms[attr.Name], 1, &value)
case Float:
value := value.(float32)
gl.Uniform1fv(s.uniforms[attr.Name], 1, &value)
case Vec2:
value := value.(mgl32.Vec2)
gl.Uniform2fv(s.uniforms[attr.Name], 1, &value[0])
case Vec3:
value := value.(mgl32.Vec3)
gl.Uniform3fv(s.uniforms[attr.Name], 1, &value[0])
case Vec4:
value := value.(mgl32.Vec4)
gl.Uniform4fv(s.uniforms[attr.Name], 1, &value[0])
case Mat2:
value := value.(mgl32.Mat2)
gl.UniformMatrix2fv(s.uniforms[attr.Name], 1, false, &value[0])
case Mat23:
value := value.(mgl32.Mat2x3)
gl.UniformMatrix2x3fv(s.uniforms[attr.Name], 1, false, &value[0])
case Mat24:
value := value.(mgl32.Mat2x4)
gl.UniformMatrix2x4fv(s.uniforms[attr.Name], 1, false, &value[0])
case Mat3:
value := value.(mgl32.Mat3)
gl.UniformMatrix3fv(s.uniforms[attr.Name], 1, false, &value[0])
case Mat32:
value := value.(mgl32.Mat3x2)
gl.UniformMatrix3x2fv(s.uniforms[attr.Name], 1, false, &value[0])
case Mat34:
value := value.(mgl32.Mat3x4)
gl.UniformMatrix3x4fv(s.uniforms[attr.Name], 1, false, &value[0])
case Mat4:
value := value.(mgl32.Mat4)
gl.UniformMatrix4fv(s.uniforms[attr.Name], 1, false, &value[0])
case Mat42:
value := value.(mgl32.Mat4x2)
gl.UniformMatrix4x2fv(s.uniforms[attr.Name], 1, false, &value[0])
case Mat43:
value := value.(mgl32.Mat4x3)
gl.UniformMatrix4x3fv(s.uniforms[attr.Name], 1, false, &value[0])
default:
panic("set uniform attr: invalid attribute type")
}
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return true
}
// Begin binds a shader program. This is necessary before using the shader.
func (s *Shader) Begin() {
s.program.bind()
}
// End unbinds a shader program and restores the previous one.
func (s *Shader) End() {
s.program.restore()
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}