func newProgram(vertexShaderSource, fragmentShaderSource string) (uint32, error) {
vertexShader, err := compileShader(vertexShaderSource, gl.VERTEX_SHADER)
if err != nil {
return 0, err
}
fragmentShader, err := compileShader(fragmentShaderSource, gl.FRAGMENT_SHADER)
if err != nil {
return 0, err
}
program := gl.CreateProgram()
gl.AttachShader(program, vertexShader)
gl.AttachShader(program, fragmentShader)
gl.LinkProgram(program)
var status int32
gl.GetProgramiv(program, gl.LINK_STATUS, &status)
if status == gl.FALSE {
var logLength int32
gl.GetProgramiv(program, gl.INFO_LOG_LENGTH, &logLength)
log := strings.Repeat("\x00", int(logLength+1))
gl.GetProgramInfoLog(program, logLength, nil, gl.Str(log))
return 0, fmt.Errorf("failed to link program: %v", log)
}
gl.DeleteShader(vertexShader)
gl.DeleteShader(fragmentShader)
return program, nil
}
//
// Load Shader
// Load vertex and fragment shader and return the compiled program.
//
// @param vertexShaderSource (string) path to the vertex shader file
// @param fragmentShaderSource (string) path to the fragment shader file
//
// @return program (uint32) a pointer to the shader program
// @return error (error) the error (if any)
//
func LoadShader(vertexShaderSource, fragmentShaderSource string) (uint32, error) {
// Loads the Vertex shader file
vertexShader, err := BuildShader(vertexShaderSource, gl.VERTEX_SHADER)
if err != nil {
return 0, err
}
// Loads the fragment shader file
fragmentShader, err := BuildShader(fragmentShaderSource, gl.FRAGMENT_SHADER)
if err != nil {
return 0, err
}
// Creates the Program
program := gl.CreateProgram()
// Attaches the Shaders to the program
gl.AttachShader(program, vertexShader)
gl.AttachShader(program, fragmentShader)
// Links the program
gl.LinkProgram(program)
// Gets any error that happened when linking the program
var status int32
gl.GetProgramiv(program, gl.LINK_STATUS, &status)
// If there was any error, parse the C error and return it as a Go error
if status == gl.FALSE {
var logLength int32
gl.GetProgramiv(program, gl.INFO_LOG_LENGTH, &logLength)
log := strings.Repeat("\x00", int(logLength+1))
gl.GetProgramInfoLog(program, logLength, nil, gl.Str(log))
return 0, fmt.Errorf("failed to link program: %v", log)
}
// Deletes the shaders
gl.DeleteShader(vertexShader)
gl.DeleteShader(fragmentShader)
// returns the program
return program, nil
}
func createProgram(vertexShaderFile, fragmentShaderFile string, uniforms, attributes []string) (*Shader, error) {
// Configure the vertex and fragment shaders
vertexShaderSource, err := ioutil.ReadFile(vertexShaderFile)
vertexShaderSource = append(vertexShaderSource, 0x00)
fragmentShaderSource, err := ioutil.ReadFile(fragmentShaderFile)
fragmentShaderSource = append(fragmentShaderSource, 0x00)
vertexShader, err := compileShader(string(vertexShaderSource), gl.VERTEX_SHADER)
if err != nil {
return nil, err
}
fragmentShader, err := compileShader(string(fragmentShaderSource), gl.FRAGMENT_SHADER)
if err != nil {
return nil, err
}
program := gl.CreateProgram()
gl.AttachShader(program, vertexShader)
gl.AttachShader(program, fragmentShader)
gl.LinkProgram(program)
var status int32
gl.GetProgramiv(program, gl.LINK_STATUS, &status)
if status == gl.FALSE {
var logLength int32
gl.GetProgramiv(program, gl.INFO_LOG_LENGTH, &logLength)
log := strings.Repeat("\x00", int(logLength+1))
gl.GetProgramInfoLog(program, logLength, nil, gl.Str(log))
return nil, fmt.Errorf("failed to link program: %v", log)
}
gl.DeleteShader(vertexShader)
gl.DeleteShader(fragmentShader)
gl.UseProgram(program)
programUniforms := make(map[string]int32)
for _, uniformName := range uniforms {
if uniformName != "" {
glstr := gl.Str(uniformName + "\x00")
programUniforms[uniformName] = gl.GetUniformLocation(program, glstr)
}
}
programAttributes := make(map[string]uint32)
for _, attribName := range attributes {
if attribName != "" {
glstr := gl.Str(attribName + "\x00")
programAttributes[attribName] = uint32(gl.GetAttribLocation(program, glstr))
}
}
return &Shader{
program: program,
uniforms: programUniforms,
attributes: programAttributes,
}, nil
}