// drawScene renders the single texture on the quad.
func (rt *rtrace) drawScene() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
gl.UseProgram(rt.shaders)
gl.Uniform1i(rt.tex2D, 0)
gl.ActiveTexture(gl.TEXTURE0 + 0)
gl.BindVertexArray(rt.vao)
gl.UniformMatrix4fv(rt.mvpId, 1, false, rt.mvp.Pointer())
gl.DrawElements(gl.TRIANGLES, int32(len(rt.faces)), gl.UNSIGNED_BYTE, 0)
// cleanup
gl.ActiveTexture(0)
gl.UseProgram(0)
gl.BindVertexArray(0)
}
// useTexture makes the given texture the active texture.
func (gc *opengl) useTexture(sampler, texUnit int32, tid uint32) {
gc.bindUniform(sampler, i1, 1, texUnit)
gl.ActiveTexture(gl.TEXTURE0 + uint32(texUnit))
gl.BindTexture(gl.TEXTURE_2D, tid)
}