Add post-curve support in color.h.
Pre-curve and post-curve describe color pipeline components
in a single GL shader invocation.The GL shader is supposed
to match struct weston_color_transform exactly.
We have the following color pipeline:
shader A -> blending -> shader B -> KMS. Both A and B shaders
using the same source file :fragment.glsl.
Each shader has pre and post curve.
The typical color pipeline with 3DLUT:
Shader A: pre-curve identity->3DLUT->blending->post-curve identity
Shader B: pre-curve->3DLUT identity->post-curve identity->KMS
The typical color pipeline with matrix (in next commits):
Shader A: pre-curve->matrix->blending->post-curve identity
Shader B: pre-curve->matrix identity->post-curve identity->KMS
The pre-curve plays role of EOTF (shader A) or INV_EOTF
(shader B) becouse we are stiching the shaders.
We assume that someone in the future may use both pre-curve
and post-curve, for example, when it is not possible to combine
these curves into 3DLUT and we will do mapping elements based on
their location in ICC profile.
Signed-off-by: Vitaly Prosyak <vitaly.prosyak@amd.com>
96f0fc3974