func (renderState *renderState) init(window gorgasm.Window) {
window.MakeContextCurrent()
renderState.window = window
width, height := window.GetSize()
// Set the viewport
gl.Viewport(0, 0, gl.Sizei(width), gl.Sizei(height))
check()
// Compile the shaders
program := Program(FragmentShader(fsh), VertexShader(vsh))
gl.UseProgram(program)
check()
// Get attributes
attrPos = uint32(gl.GetAttribLocation(program, "pos"))
attrTexIn = uint32(gl.GetAttribLocation(program, "texIn"))
unifTexture = gl.GetUniformLocation(program, "texture")
gl.EnableVertexAttribArray(attrPos)
gl.EnableVertexAttribArray(attrTexIn)
check()
// Upload vertices data
gl.GenBuffers(1, &verticesArrayBuffer)
gl.BindBuffer(gl.ARRAY_BUFFER, verticesArrayBuffer)
gl.BufferData(gl.ARRAY_BUFFER, gl.SizeiPtr(len(vertices))*4, gl.Void(&vertices[0]), gl.STATIC_DRAW)
check()
// Upload texture data
img, err := loadImage(GOPHER_PNG)
if err != nil {
panic(err)
}
// Prepare the image to be placed on a texture.
bounds := img.Bounds()
imgWidth, imgHeight := bounds.Size().X, bounds.Size().Y
buffer := make([]byte, imgWidth*imgHeight*4)
index := 0
for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
for x := bounds.Min.X; x < bounds.Max.X; x++ {
r, g, b, a := img.At(x, y).RGBA()
buffer[index] = byte(r)
buffer[index+1] = byte(g)
buffer[index+2] = byte(b)
buffer[index+3] = byte(a)
index += 4
}
}
gl.GenTextures(1, &textureBuffer)
gl.BindTexture(gl.TEXTURE_2D, textureBuffer)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.Sizei(imgWidth), gl.Sizei(imgHeight), 0, gl.RGBA, gl.UNSIGNED_BYTE, gl.Void(&buffer[0]))
check()
gl.ClearColor(0.0, 0.0, 0.0, 1.0)
}
func (renderState *renderState) draw() {
gl.Clear(gl.COLOR_BUFFER_BIT)
gl.BindBuffer(gl.ARRAY_BUFFER, verticesArrayBuffer)
gl.VertexAttribPointer(attrPos, 4, gl.FLOAT, false, 6*4, 0)
// bind texture - FIX size of vertex
gl.VertexAttribPointer(attrTexIn, 2, gl.FLOAT, false, 6*4, 4*4)
gl.ActiveTexture(gl.TEXTURE0)
gl.BindTexture(gl.TEXTURE_2D, textureBuffer)
gl.Uniform1i(int32(unifTexture), 0)
gl.DrawArrays(gl.TRIANGLE_FAN, 0, 4)
gl.Flush()
gl.Finish()
}
func (b *buffer) bind() {
gl.BindBuffer(gl.ARRAY_BUFFER, b.target)
}