github.com/coming-chat/gomobile@v0.0.0-20220601074111-56995f7d7aba/exp/gl/glutil/glutil.go (about)

     1  // Copyright 2014 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build darwin || linux || windows
     6  // +build darwin linux windows
     7  
     8  package glutil // import "golang.org/x/mobile/exp/gl/glutil"
     9  
    10  import (
    11  	"fmt"
    12  
    13  	"golang.org/x/mobile/exp/f32"
    14  	"golang.org/x/mobile/gl"
    15  )
    16  
    17  // CreateProgram creates, compiles, and links a gl.Program.
    18  func CreateProgram(glctx gl.Context, vertexSrc, fragmentSrc string) (gl.Program, error) {
    19  	program := glctx.CreateProgram()
    20  	if program.Value == 0 {
    21  		return gl.Program{}, fmt.Errorf("glutil: no programs available")
    22  	}
    23  
    24  	vertexShader, err := loadShader(glctx, gl.VERTEX_SHADER, vertexSrc)
    25  	if err != nil {
    26  		return gl.Program{}, err
    27  	}
    28  	fragmentShader, err := loadShader(glctx, gl.FRAGMENT_SHADER, fragmentSrc)
    29  	if err != nil {
    30  		glctx.DeleteShader(vertexShader)
    31  		return gl.Program{}, err
    32  	}
    33  
    34  	glctx.AttachShader(program, vertexShader)
    35  	glctx.AttachShader(program, fragmentShader)
    36  	glctx.LinkProgram(program)
    37  
    38  	// Flag shaders for deletion when program is unlinked.
    39  	glctx.DeleteShader(vertexShader)
    40  	glctx.DeleteShader(fragmentShader)
    41  
    42  	if glctx.GetProgrami(program, gl.LINK_STATUS) == 0 {
    43  		defer glctx.DeleteProgram(program)
    44  		return gl.Program{}, fmt.Errorf("glutil: %s", glctx.GetProgramInfoLog(program))
    45  	}
    46  	return program, nil
    47  }
    48  
    49  func loadShader(glctx gl.Context, shaderType gl.Enum, src string) (gl.Shader, error) {
    50  	shader := glctx.CreateShader(shaderType)
    51  	if shader.Value == 0 {
    52  		return gl.Shader{}, fmt.Errorf("glutil: could not create shader (type %v)", shaderType)
    53  	}
    54  	glctx.ShaderSource(shader, src)
    55  	glctx.CompileShader(shader)
    56  	if glctx.GetShaderi(shader, gl.COMPILE_STATUS) == 0 {
    57  		defer glctx.DeleteShader(shader)
    58  		return gl.Shader{}, fmt.Errorf("shader compile: %s", glctx.GetShaderInfoLog(shader))
    59  	}
    60  	return shader, nil
    61  }
    62  
    63  // writeAffine writes the contents of an Affine to a 3x3 matrix GL uniform.
    64  func writeAffine(glctx gl.Context, u gl.Uniform, a *f32.Affine) {
    65  	var m [9]float32
    66  	m[0*3+0] = a[0][0]
    67  	m[0*3+1] = a[1][0]
    68  	m[0*3+2] = 0
    69  	m[1*3+0] = a[0][1]
    70  	m[1*3+1] = a[1][1]
    71  	m[1*3+2] = 0
    72  	m[2*3+0] = a[0][2]
    73  	m[2*3+1] = a[1][2]
    74  	m[2*3+2] = 1
    75  	glctx.UniformMatrix3fv(u, m[:])
    76  }