From 67073db49ced1bb561783a7f4cb862c1bad0e865 Mon Sep 17 00:00:00 2001
From: Nicholas Bishop <nicholasbishop@gmail.com>
Date: Sat, 27 Jun 2009 21:14:04 +0000
Subject: 2.5/Sculpt:

Improved sculpting in perspective mode; starting a stroke on the background would sometimes result in the brush having a huge effect on the mesh. Fixed by waiting to start the stroke until the mouse moves over the model.

The fix is not quite perfect, because detection of the edge of the model is based on the depth buffer, so other things that change the depth buffer, like the grid and axis lines in the 3d view, can throw off the calculation.
---
 source/blender/editors/sculpt_paint/sculpt.c | 56 ++++++++++++++++++----------
 1 file changed, 36 insertions(+), 20 deletions(-)

diff --git a/source/blender/editors/sculpt_paint/sculpt.c b/source/blender/editors/sculpt_paint/sculpt.c
index 318abf792c1..8f0b52ef3a1 100644
--- a/source/blender/editors/sculpt_paint/sculpt.c
+++ b/source/blender/editors/sculpt_paint/sculpt.c
@@ -1343,9 +1343,6 @@ static int sculpt_brush_stroke_invoke(bContext *C, wmOperator *op, wmEvent *even
 	Sculpt *sd = CTX_data_tool_settings(C)->sculpt;
 
 	view3d_operator_needs_opengl(C);
-	sculpt_brush_stroke_init_properties(C, op, event, sd->session);
-
-	sculptmode_update_all_projverts(sd->session);
 
 	/* TODO: Shouldn't really have to do this at the start of every
 	   stroke, but sculpt would need some sort of notification when
@@ -1414,34 +1411,53 @@ static int sculpt_brush_stroke_modal(bContext *C, wmOperator *op, wmEvent *event
 {
 	PointerRNA itemptr;
 	Sculpt *sd = CTX_data_tool_settings(C)->sculpt;
+	ARegion *ar = CTX_wm_region(C);
 	float center[3];
 	int mouse[2] = {event->x, event->y};
+	float cur_depth;
 
 	sculpt_update_mesh_elements(C);
 
-	unproject(sd->session->cache->mats, center, event->x, event->y,
-		  read_cached_depth(&sd->session->cache->vc, event->x, event->y));
+	if(!sd->session->cache) {
+		ViewContext vc;
+		view3d_set_viewcontext(C, &vc);
+		cur_depth = read_cached_depth(&vc, event->x, event->y);
 
-	/* Add to stroke */
-	RNA_collection_add(op->ptr, "stroke", &itemptr);
-	RNA_float_set_array(&itemptr, "location", center);
-	RNA_int_set_array(&itemptr, "mouse", mouse);
-	RNA_boolean_set(&itemptr, "flip", event->shift);
-	sculpt_update_cache_variants(sd, &itemptr);
+		/* Don't start the stroke until a valid depth is found */
+		if(cur_depth < 1.0 - FLT_EPSILON) {
+			sculpt_brush_stroke_init_properties(C, op, event, sd->session);
+			sculptmode_update_all_projverts(sd->session);
+		}
 
-	sculpt_restore_mesh(sd);
-	do_symmetrical_brush_actions(CTX_data_tool_settings(C)->sculpt, sd->session->cache);
+		ED_region_tag_redraw(ar);
+	}
 
-	sculpt_flush_update(C);
-	sculpt_post_stroke_free(sd->session);
+	if(sd->session->cache) {
+		cur_depth = read_cached_depth(&sd->session->cache->vc, event->x, event->y);
+		unproject(sd->session->cache->mats, center, event->x, event->y, cur_depth);
 
-	/* Finished */
-	if(event->type == LEFTMOUSE && event->val == 0) {
-		request_depth_update(sd->session->cache->vc.rv3d);
+		/* Add to stroke */
+		RNA_collection_add(op->ptr, "stroke", &itemptr);
+		RNA_float_set_array(&itemptr, "location", center);
+		RNA_int_set_array(&itemptr, "mouse", mouse);
+		RNA_boolean_set(&itemptr, "flip", event->shift);
+		sculpt_update_cache_variants(sd, &itemptr);
+
+		sculpt_restore_mesh(sd);
+		do_symmetrical_brush_actions(CTX_data_tool_settings(C)->sculpt, sd->session->cache);
 
-		sculpt_cache_free(sd->session->cache);
+		sculpt_flush_update(C);
+		sculpt_post_stroke_free(sd->session);
+	}
 
-		sculpt_undo_push(C, sd);
+	/* Finished */
+	if(event->type == LEFTMOUSE && event->val == 0) {
+		if(sd->session->cache) {
+			request_depth_update(sd->session->cache->vc.rv3d);
+			sculpt_cache_free(sd->session->cache);
+			sd->session->cache = NULL;
+			sculpt_undo_push(C, sd);
+		}
 
 		return OPERATOR_FINISHED;
 	}
-- 
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