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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build darwin || linux || windows
package glutil
import (
"fmt"
"golang.org/x/mobile/exp/f32"
"golang.org/x/mobile/gl"
)
// CreateProgram creates, compiles, and links a gl.Program.
func CreateProgram(glctx gl.Context, vertexSrc, fragmentSrc string) (gl.Program, error) {
program := glctx.CreateProgram()
if program.Value == 0 {
return gl.Program{}, fmt.Errorf("glutil: no programs available")
}
vertexShader, err := loadShader(glctx, gl.VERTEX_SHADER, vertexSrc)
if err != nil {
return gl.Program{}, err
}
fragmentShader, err := loadShader(glctx, gl.FRAGMENT_SHADER, fragmentSrc)
if err != nil {
glctx.DeleteShader(vertexShader)
return gl.Program{}, err
}
glctx.AttachShader(program, vertexShader)
glctx.AttachShader(program, fragmentShader)
glctx.LinkProgram(program)
// Flag shaders for deletion when program is unlinked.
glctx.DeleteShader(vertexShader)
glctx.DeleteShader(fragmentShader)
if glctx.GetProgrami(program, gl.LINK_STATUS) == 0 {
defer glctx.DeleteProgram(program)
return gl.Program{}, fmt.Errorf("glutil: %s", glctx.GetProgramInfoLog(program))
}
return program, nil
}
func loadShader(glctx gl.Context, shaderType gl.Enum, src string) (gl.Shader, error) {
shader := glctx.CreateShader(shaderType)
if shader.Value == 0 {
return gl.Shader{}, fmt.Errorf("glutil: could not create shader (type %v)", shaderType)
}
glctx.ShaderSource(shader, src)
glctx.CompileShader(shader)
if glctx.GetShaderi(shader, gl.COMPILE_STATUS) == 0 {
defer glctx.DeleteShader(shader)
return gl.Shader{}, fmt.Errorf("shader compile: %s", glctx.GetShaderInfoLog(shader))
}
return shader, nil
}
// writeAffine writes the contents of an Affine to a 3x3 matrix GL uniform.
func writeAffine(glctx gl.Context, u gl.Uniform, a *f32.Affine) {
var m [9]float32
m[0*3+0] = a[0][0]
m[0*3+1] = a[1][0]
m[0*3+2] = 0
m[1*3+0] = a[0][1]
m[1*3+1] = a[1][1]
m[1*3+2] = 0
m[2*3+0] = a[0][2]
m[2*3+1] = a[1][2]
m[2*3+2] = 1
glctx.UniformMatrix3fv(u, m[:])
}
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