Large change to the way sculptmode drawing works. The default is now to draw

using the standard drawing functions. Enabling the "Partial Redraw" item in the
sculpt menu will turn on the optimizations which stores unmodified parts of the
color buffer and only redraws the polygons that are within the modified area(s).

The Partial Redraw option uses the accumulation buffer to store the copy, and
unfortunately this is not accelerated on older cards. There are alternatives,
e.g. drawing to an auxiliary buffer or downloading the data from the graphics
card with glReadPixels, but there's no guarantee that these will run at an
acceptable speed on older graphics cards either. For the cards that do
accelerate the accumulation buffer (for nvidia cards, I would assume that is at
least FX5200 and up, and maybe earlier) it provides a very significant speedup.

1 files changed, 14 insertions, 11 deletions

diff --git a/source/blender/src/sculptmode.c b/source/blender/src/sculptmode.c
index 3b2c46e6222..c40fcf5a65b 100644
--- a/source/blender/src/sculptmode.c
+++ b/source/blender/src/sculptmode.c
@@ -175,6 +175,7 @@ void sculptmode_init(Scene *sce)
 	sd->averaging= 1;
 	sd->texscale= 100;
 	sd->texrept= SCULPTREPT_DRAG;
+	sd->draw_mode= 0;
 }
 
 /* Free G.sculptdata->vertexusers */
@@ -428,7 +429,7 @@ void sculptmode_undo_update(SculptUndoStep *newcur)
 	
 	set_sculpt_object(ob);
 	
-	if(modifiers_getVirtualModifierList(ob))
+	if(!sd->draw_mode || modifiers_getVirtualModifierList(ob))
 		DAG_object_flush_update(G.scene, OBACT, OB_RECALC_DATA);
 
 	if(G.vd->depths) G.vd->depths->damaged= 1;
@@ -1558,7 +1559,8 @@ void sculpt()
 	e.layer_store= NULL;
 
 	/* Capture original copy */
-	glAccum(GL_LOAD, 1);
+	if(sd->draw_mode)
+		glAccum(GL_LOAD, 1);
 
 	while (get_mbut() & mousebut) {
 		getmouseco_areawin(mouse);
@@ -1604,14 +1606,17 @@ void sculpt()
 			if(modifier_calculations)
 				DAG_object_flush_update(G.scene, OBACT, OB_RECALC_DATA);
 
-			if(modifier_calculations || sd->brush_type == GRAB_BRUSH) {
+			if(modifier_calculations || sd->brush_type == GRAB_BRUSH || !sd->draw_mode) {
 				calc_damaged_verts(&damaged_verts,e.grabdata);
-
 				scrarea_do_windraw(curarea);
 				screen_swapbuffers();
-			} else {
+			} else { /* Optimized drawing */
 				calc_damaged_verts(&damaged_verts,e.grabdata);
 
+				/* Draw the stored image to the screen */
+				glAccum(GL_RETURN, 1);
+
+				/* Clear each of the area(s) modified by the brush */
 				for(rn=damaged_rects.first; rn; rn= rn->next) {
 					float col[3];
 					rcti clp= rn->r;
@@ -1636,21 +1641,19 @@ void sculpt()
 					glClearColor(col[0], col[1], col[2], 0.0);
 					glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
 				}
-				glDisable(GL_SCISSOR_TEST);
 				
+				/* Draw all the polygons that are inside the modified area(s) */
+				glDisable(GL_SCISSOR_TEST);
 				sculptmode_draw_mesh(1);
-
 				glAccum(GL_LOAD, 1);
+				glEnable(GL_SCISSOR_TEST);
 				
 				/* Draw cursor */
 				persp(PERSP_WIN);
 				glDisable(GL_DEPTH_TEST);
 				fdrawXORcirc((float)mouse[0],(float)mouse[1],sculptmode_brush()->size);
-				glRasterPos2i(0, 0);
-				myswapbuffers();
-				glAccum(GL_RETURN, 1);
 				
-				glEnable(GL_SCISSOR_TEST);
+				myswapbuffers();
 			}
 
 			BLI_freelistN(&damaged_rects);