Bugreport #4787 mentioned subpixel render issues, especially for small

images (like used for rendering icons).

When working during Orange on new render pipeline, I've left this topic
alone for a while... subpixel precision testing is very time consuming and
needs concentration for a while. :)

This commit brings back precision as it was for 2.41. Below a short
explanation of the solved issues.

- the window matrix for rendering is kept constant during all OSA passes,
  this to ensure clipping happens for each pass identically.
- a subpixel offset is only applied on filling in the z-buffer
- this offset is inverse corrected for shadepixel code, only on 2 places

Another nasty issue is that for filtered rendering (gauss etc), the tiles
(or entire image) is temporally increased 2 pixel in size. This caused a
'dark' (or sky color) edge on the rendering. During Orange that was solved
with a hardcoded clipping offset value, which only corrected for larger
pictures (like > 500 pixels in size).
Now this clipping offset is correctly calculated, based on render size.

Last issue: the view border in 3d window was calculated using integers,
giving small errors in display too. Now it uses float, so visually the
view border is more close to what a render shows.

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/include/BSE_drawview.h b/source/blender/include/BSE_drawview.h
index 70793f88ce2..041381bbb1a 100644
--- a/source/blender/include/BSE_drawview.h
+++ b/source/blender/include/BSE_drawview.h
@@ -35,7 +35,7 @@
 
 struct Object;
 struct BGpic;
-struct rcti;
+struct rctf;
 struct ScrArea;
 struct ImBuf;
 
@@ -61,7 +61,7 @@ void drawview3dspace(struct ScrArea *sa, void *spacedata);
 void drawview3d_render(struct View3D *v3d, int winx, int winy);
 
 int update_time(void);
-void calc_viewborder(struct View3D *v3d, struct rcti *viewborder_r);
+void calc_viewborder(struct View3D *v3d, struct rctf *viewborder_r);
 void view3d_set_1_to_1_viewborder(struct View3D *v3d);
 
 int view3d_test_clipping(struct View3D *v3d, float *vec);