Keying screen: small fixes and improvements from tomato

- Fixed issues with calculating matte with balance != 0.5
  It used to be used concave combination of minimal and maximal
  channel values which could be inpredictable.
  Use concave combination of two non-major channels sorted
  by their index, so such combination would always use the same
  coefficients for particular non-major channels.

- Added despill balance slider which defines balance between
  non-major channels used for calculating average of two
  colors. Difference between average value and pixel value of
  major screen channel defines amount of despill. Balance of
  0.5 gives the same behavior as it was before this slider
  was added.

---
svn merge -r48678:48679 -r48789:48790 ^/branches/soc-2011-tomato

1 files changed, 1 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_node_types.h b/source/blender/makesdna/DNA_node_types.h
index 58a6332515e..1e2f6eabce6 100644
--- a/source/blender/makesdna/DNA_node_types.h
+++ b/source/blender/makesdna/DNA_node_types.h
@@ -652,6 +652,7 @@ typedef struct NodeKeyingScreenData {
 typedef struct NodeKeyingData {
 	float screen_balance;
 	float despill_factor;
+	float despill_balance;
 	int edge_kernel_radius;
 	float edge_kernel_tolerance;
 	float clip_black, clip_white;