Matcap support in 3D Viewport.

Full log is here:
http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.66/Usability#Matcap_in_3D_viewport

Implementation notes:

- Matcaps are an extension of Solid draw mode, and don't show in other drawmodes.
  (It's mostly intended to aid modeling/sculpt)

- By design, Matcaps are a UI feature, and only stored locally for the UI itself, and
  won't affect rendering or materials.

- Currently a set of 16 (GPL licensed) Matcaps have been compiled into Blender. 
  It doesn't take memory or cpu time, until you use it.

- Brush Icons and Matcaps use same code now, and only get generated/allocated on
  actually using it (instead of on startup).

- The current set might get new or different images still, based on user feedback.

- Matcap images are 512x512 pixels, so each image takes 1 Mb memory. Unused matcaps get 
  freed immediately. The Matcap icon previews (128x128 pixels) stay in memory.

- Loading own matcap image files will be added later. That needs design and code work 
  to get it stable and memory-friendly.

- The GLSL code uses the ID PreviewImage for matcaps. I tested it using the existing
  Material previews, which has its limits... especially for textured previews the
  normal-mapped matcap won't look good.

1 files changed, 4 insertions, 1 deletions

diff --git a/source/blender/gpu/GPU_extensions.h b/source/blender/gpu/GPU_extensions.h
index 7eaa4084e61..66a7c917a55 100644
--- a/source/blender/gpu/GPU_extensions.h
+++ b/source/blender/gpu/GPU_extensions.h
@@ -38,7 +38,8 @@ extern "C" {
 
 struct Image;
 struct ImageUser;
-
+struct PreviewImage;
+	
 struct GPUTexture;
 typedef struct GPUTexture GPUTexture;
 
@@ -112,6 +113,8 @@ GPUTexture *GPU_texture_create_depth(int w, int h, char err_out[256]);
 GPUTexture *GPU_texture_create_vsm_shadow_map(int size, char err_out[256]);
 GPUTexture *GPU_texture_from_blender(struct Image *ima,
 	struct ImageUser *iuser, int isdata, double time, int mipmap);
+GPUTexture *GPU_texture_from_preview(struct PreviewImage *prv, int mipmap);
+
 void GPU_texture_free(GPUTexture *tex);
 
 void GPU_texture_ref(GPUTexture *tex);