Potential fix for T43987, ambient occlusion different between offscreen

and on screen rendering.

Aaaaah, the beauty of driver implementations of OpenGL!

Turns out the problem here is that drivers calculate df/dy differently
in some cases (probably because OpenGL counts y reverse to how the
window system does, so drivers can get confused).

Fixed this for the ATI case based on info we have so far, there's also
the Intel case which will be handled separately (missing info on Intel's
renderer string etc).

Unfortunately we can't really fix this for the general case so we'll
have to haldle cases as they come in our tracker and by adding silly
string comparisons in our GPU initialization module <sigh>.

1 files changed, 1 insertions, 0 deletions

diff --git a/source/blender/gpu/GPU_extensions.h b/source/blender/gpu/GPU_extensions.h
index c006540ddf4..de0af815bf4 100644
--- a/source/blender/gpu/GPU_extensions.h
+++ b/source/blender/gpu/GPU_extensions.h
@@ -66,6 +66,7 @@ bool GPU_instanced_drawing_support(void);
 
 int GPU_max_texture_size(void);
 int GPU_color_depth(void);
+void GPU_get_dfdy_factors(float fac[2]);
 
 void GPU_code_generate_glsl_lib(void);