ebiten/graphics/opengl/shader/shader.go

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package shader
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// #cgo LDFLAGS: -framework OpenGL
//
// #include <OpenGL/gl.h>
// #include <stdlib.h>
import "C"
import (
"unsafe"
)
type shader struct {
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id C.GLuint
name string
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source string
}
var (
vertexShader = &shader{
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id: 0,
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name: "vertex_shader",
source: `
attribute /*highp*/ vec2 vertex;
attribute /*highp*/ vec2 texture;
uniform /*highp*/ mat4 projection_matrix;
uniform /*highp*/ mat4 modelview_matrix;
varying /*highp*/ vec2 tex_coord;
void main(void) {
tex_coord = texture;
gl_Position = projection_matrix * modelview_matrix * vec4(vertex, 0, 1);
}
`,
}
fragmentShader = &shader{
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id: 0,
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name: "fragment_shader",
source: `
uniform /*lowp*/ sampler2D texture;
varying /*highp*/ vec2 tex_coord;
void main(void) {
gl_FragColor = texture2D(texture, tex_coord);
}
`,
}
colorMatrixShader = &shader{
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id: 0,
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name: "color_matrix_shader",
source: `
uniform /*highp*/ sampler2D texture;
uniform /*lowp*/ mat4 color_matrix;
uniform /*lowp*/ vec4 color_matrix_translation;
varying /*highp*/ vec2 tex_coord;
void main(void) {
/*lowp*/ vec4 color = texture2D(texture, tex_coord);
gl_FragColor = (color_matrix * color) + color_matrix_translation;
}
`,
}
)
var (
programRegular = C.GLuint(0)
programColorMatrix = C.GLuint(0)
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)
func (s *shader) compile() {
csource := (*C.GLchar)(C.CString(s.source))
// TODO: defer?
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// defer C.free(unsafe.Pointer(csource))
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C.glShaderSource(s.id, 1, &csource, nil)
C.glCompileShader(s.id)
compiled := C.GLint(C.GL_FALSE)
C.glGetShaderiv(s.id, C.GL_COMPILE_STATUS, &compiled)
if compiled == C.GL_FALSE {
s.showShaderLog()
panic("shader compile failed: " + s.name)
}
}
func (s *shader) showShaderLog() {
logSize := C.GLint(0)
C.glGetShaderiv(s.id, C.GL_INFO_LOG_LENGTH, &logSize)
if logSize == 0 {
return
}
length := C.GLsizei(0)
buffer := make([]C.GLchar, logSize)
C.glGetShaderInfoLog(s.id, C.GLsizei(logSize), &length, &buffer[0])
message := string(C.GoBytes(unsafe.Pointer(&buffer[0]), C.int(length)))
print("shader error (", s.name, "):\n", message)
}