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, 5 insertions, 5 deletions

diff --git a/source/blender/src/editview.c b/source/blender/src/editview.c
index 76d857826b6..001105c43a9 100644
--- a/source/blender/src/editview.c
+++ b/source/blender/src/editview.c
@@ -1980,14 +1980,14 @@ void set_render_border(void)
 	
 	val= get_border(&rect, 3);
 	if(val) {
-		rcti vb;
+		rctf vb;
 
 		calc_viewborder(G.vd, &vb);
 
-		G.scene->r.border.xmin= (float) (rect.xmin-vb.xmin)/(vb.xmax-vb.xmin);
-		G.scene->r.border.ymin= (float) (rect.ymin-vb.ymin)/(vb.ymax-vb.ymin);
-		G.scene->r.border.xmax= (float) (rect.xmax-vb.xmin)/(vb.xmax-vb.xmin);
-		G.scene->r.border.ymax= (float) (rect.ymax-vb.ymin)/(vb.ymax-vb.ymin);
+		G.scene->r.border.xmin= ((float)rect.xmin-vb.xmin)/(vb.xmax-vb.xmin);
+		G.scene->r.border.ymin= ((float)rect.ymin-vb.ymin)/(vb.ymax-vb.ymin);
+		G.scene->r.border.xmax= ((float)rect.xmax-vb.xmin)/(vb.xmax-vb.xmin);
+		G.scene->r.border.ymax= ((float)rect.ymax-vb.ymin)/(vb.ymax-vb.ymin);
 		
 		CLAMP(G.scene->r.border.xmin, 0.0, 1.0);
 		CLAMP(G.scene->r.border.ymin, 0.0, 1.0);