func main() {
initialWidth, initialHeight := 1280, 720
runtime.LockOSThread()
if sdlInit := sdl.Init(sdl.INIT_VIDEO); sdlInit != 0 {
panic("SDL init error")
}
reinitScreen(initialWidth, initialHeight)
defer cleanExit(true, false)
if err := gl.Init(); err != nil {
panic(err)
}
gl.Enable(gl.BLEND)
gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
gl.Enable(gl.DEPTH)
defer cleanExit(false, true)
glSetupShaderProg(&shaderTextureCreator, false)
glSetupShaderProg(&shaderTextureDisplay, true)
glFillBuffer(rttVerts, &rttVertBuf)
glFillBuffer(dispVerts, &dispVertBuf)
gl.GenTextures(1, &rttFrameTex)
gl.BindTexture(gl.TEXTURE_2D, rttFrameTex)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT)
if doRtt {
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, texSize, texSize, 0, gl.RGBA, gl.UNSIGNED_BYTE, nil)
gl.GenFramebuffers(1, &rttFrameBuf)
gl.BindFramebuffer(gl.FRAMEBUFFER, rttFrameBuf)
gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, rttFrameTex, 0)
gl.BindFramebuffer(gl.FRAMEBUFFER, 0)
} else {
glFillTextureFromImageFile("texture.jpg")
}
gl.BindTexture(gl.TEXTURE_2D, 0)
gl.ClearColor(0.3, 0.6, 0.9, 1)
gl.Clear(gl.COLOR_BUFFER_BIT)
gl.ActiveTexture(gl.TEXTURE0)
for {
if evt := sdl.PollEvent(); evt != nil {
switch event := evt.(type) {
case *sdl.ResizeEvent:
reinitScreen(int(event.W), int(event.H))
case *sdl.QuitEvent:
return
}
} else {
if doRtt {
renderToTexture()
}
renderToScreen()
sdl.GL_SwapBuffers()
}
}
sdl.Quit()
}
func renderToScreen() {
gl.BindFramebuffer(gl.FRAMEBUFFER, 0)
gl.Viewport(0, 0, winWidth, winHeight)
gl.UseProgram(shaderTextureDisplay.glProg)
gl.BindTexture(gl.TEXTURE_2D, rttFrameTex)
gl.Uniform1i(shaderTextureDisplay.unifTex, 0)
gl.BindBuffer(gl.ARRAY_BUFFER, dispVertBuf)
gl.EnableVertexAttribArray(shaderTextureDisplay.attrPos)
gl.VertexAttribPointer(shaderTextureDisplay.attrPos, 3, gl.FLOAT, gl.FALSE, 0, gl.Pointer(nil))
gl.DrawArrays(gl.TRIANGLE_FAN, 0, 4)
gl.DisableVertexAttribArray(shaderTextureDisplay.attrPos)
gl.BindBuffer(gl.ARRAY_BUFFER, 0)
}
func renderToTexture() {
gl.BindFramebuffer(gl.FRAMEBUFFER, rttFrameBuf)
gl.Viewport(0, 0, texSize, texSize)
gl.ClearColor(0.9, 0.6, 0.3, 1)
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
gl.UseProgram(shaderTextureCreator.glProg)
gl.BindBuffer(gl.ARRAY_BUFFER, rttVertBuf)
gl.EnableVertexAttribArray(shaderTextureCreator.attrPos)
gl.VertexAttribPointer(shaderTextureCreator.attrPos, 2, gl.FLOAT, gl.FALSE, 0, gl.Pointer(nil))
gl.DrawArrays(gl.TRIANGLE_FAN, 0, 4)
gl.DisableVertexAttribArray(shaderTextureCreator.attrPos)
gl.BindBuffer(gl.ARRAY_BUFFER, 0)
}