126 lines
2.8 KiB
Go
126 lines
2.8 KiB
Go
package pixelgl
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import (
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"fmt"
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"github.com/go-gl/gl/v3.3-core/gl"
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"github.com/pkg/errors"
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)
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// Shader is an OpenGL shader program.
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type Shader struct {
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parent BeginEnder
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program uint32
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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.
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func NewShader(parent BeginEnder, vertexShader, fragmentShader string) (*Shader, error) {
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parent.Begin()
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defer parent.End()
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shader := &Shader{
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parent: parent,
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}
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err, glerr := DoErrGLErr(func() error {
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var vshader, fshader uint32
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// vertex shader
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{
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vshader = gl.CreateShader(gl.VERTEX_SHADER)
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src, free := gl.Strs(vertexShader)
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defer free()
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length := int32(len(vertexShader))
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gl.ShaderSource(vshader, 1, src, &length)
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gl.CompileShader(vshader)
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var (
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success int32
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infoLog = make([]byte, 512)
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)
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gl.GetShaderiv(vshader, gl.COMPILE_STATUS, &success)
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if success == 0 {
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gl.GetShaderInfoLog(vshader, int32(len(infoLog)), nil, &infoLog[0])
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return fmt.Errorf("error compiling vertex shader: %s", string(infoLog))
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}
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}
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// fragment shader
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{
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fshader = gl.CreateShader(gl.FRAGMENT_SHADER)
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src, free := gl.Strs(fragmentShader)
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defer free()
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length := int32(len(fragmentShader))
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gl.ShaderSource(fshader, 1, src, &length)
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gl.CompileShader(fshader)
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var (
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success int32
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infoLog = make([]byte, 512)
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)
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gl.GetShaderiv(fshader, gl.COMPILE_STATUS, &success)
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if success == 0 {
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gl.GetShaderInfoLog(fshader, int32(len(infoLog)), nil, &infoLog[0])
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return fmt.Errorf("error compiling fragment shader: %s", string(infoLog))
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}
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}
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// shader program
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{
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shader.program = gl.CreateProgram()
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gl.AttachShader(shader.program, vshader)
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gl.AttachShader(shader.program, fshader)
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gl.LinkProgram(shader.program)
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var (
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success int32
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infoLog = make([]byte, 512)
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)
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gl.GetProgramiv(shader.program, gl.LINK_STATUS, &success)
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if success == 0 {
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gl.GetProgramInfoLog(shader.program, int32(len(infoLog)), nil, &infoLog[0])
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return fmt.Errorf("error linking shader program: %s", string(infoLog))
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}
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}
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gl.DeleteShader(vshader)
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gl.DeleteShader(fshader)
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return nil
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})
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if err != nil {
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if glerr != nil {
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err = errors.Wrap(glerr, err.Error())
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}
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return nil, err
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}
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if glerr != nil {
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return nil, glerr
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}
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return shader, nil
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}
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// Delete deletes a shader program. Don't use a shader after deletion.
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func (s *Shader) Delete() {
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DoNoBlock(func() {
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gl.DeleteProgram(s.program)
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})
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}
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// Begin starts using a shader program.
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func (s *Shader) Begin() {
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s.parent.Begin()
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DoNoBlock(func() {
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gl.UseProgram(s.program)
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})
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}
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// End stops using a shader program.
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func (s *Shader) End() {
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DoNoBlock(func() {
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gl.UseProgram(0)
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})
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s.parent.End()
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}
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