option to lock alpha while projection painting.

(commit 27538 by Campbell from render25 branch)

3 files changed, 14 insertions, 0 deletions

diff --git a/source/blender/editors/sculpt_paint/paint_image.c b/source/blender/editors/sculpt_paint/paint_image.c
index 6137d83e77e..9fc858a191f 100644
--- a/source/blender/editors/sculpt_paint/paint_image.c
+++ b/source/blender/editors/sculpt_paint/paint_image.c
@@ -3705,6 +3705,7 @@ static void *do_projectpaint_thread(void *ph_v)
 	float mask = 1.0f; /* airbrush wont use mask */
 	unsigned short mask_short;
 	float size_half = ((float)ps->brush->size) * 0.5f;
+	short lock_alpha= ELEM(ps->brush->blend, IMB_BLEND_ERASE_ALPHA, IMB_BLEND_ADD_ALPHA) ? 0 : ps->brush->flag & BRUSH_LOCK_ALPHA;
 	
 	LinkNode *smearPixels = NULL;
 	LinkNode *smearPixels_f = NULL;
@@ -3833,6 +3834,12 @@ static void *do_projectpaint_thread(void *ph_v)
 								break;
 							}
 						}
+
+						if(lock_alpha) {
+							if (is_floatbuf)	projPixel->pixel.f_pt[3]= projPixel->origColor.f[3];
+							else				projPixel->pixel.ch_pt[3]= projPixel->origColor.ch[3];
+						}
+
 						/* done painting */
 					}
 				}
diff --git a/source/blender/makesdna/DNA_brush_types.h b/source/blender/makesdna/DNA_brush_types.h
index 163c8122fb7..14930f85e63 100644
--- a/source/blender/makesdna/DNA_brush_types.h
+++ b/source/blender/makesdna/DNA_brush_types.h
@@ -86,6 +86,7 @@ typedef struct Brush {
 #define BRUSH_SMOOTH_STROKE		2048
 #define BRUSH_PERSISTENT		4096
 #define BRUSH_ACCUMULATE		8192
+#define BRUSH_LOCK_ALPHA		16384
 
 /* Brush.sculpt_tool */
 #define SCULPT_TOOL_DRAW    1
diff --git a/source/blender/makesrna/intern/rna_brush.c b/source/blender/makesrna/intern/rna_brush.c
index 2d81a9d66c1..df08dc7b861 100644
--- a/source/blender/makesrna/intern/rna_brush.c
+++ b/source/blender/makesrna/intern/rna_brush.c
@@ -279,6 +279,12 @@ static void rna_def_brush(BlenderRNA *brna)
 	RNA_def_property_boolean_sdna(prop, NULL, "flag", BRUSH_FIXED_TEX);
 	RNA_def_property_ui_text(prop, "Fixed Texture", "Keep texture origin in fixed position");
 	RNA_def_property_update(prop, 0, "rna_Brush_update"); */
+	
+	/* only for projection paint, TODO, other paint modes */
+	prop= RNA_def_property(srna, "use_alpha", PROP_BOOLEAN, PROP_NONE);
+	RNA_def_property_boolean_negative_sdna(prop, NULL, "flag", BRUSH_LOCK_ALPHA);
+	RNA_def_property_ui_text(prop, "Alpha", "When this is disabled, lock alpha while painting");
+	RNA_def_property_update(prop, 0, "rna_Brush_update");
 
 	prop= RNA_def_property(srna, "curve", PROP_POINTER, PROP_NONE);
 	RNA_def_property_flag(prop, PROP_NEVER_NULL);