From 20b23e3b5e032f4af6e6e14c1496333ecac409f8 Mon Sep 17 00:00:00 2001
From: Ton Roosendaal <ton@blender.org>
Date: Sun, 23 Oct 2005 19:16:37 +0000
Subject: [PATCH] The ctrl+click extrude now calculates a rotation, so you can
 do wild quick modeling! It detects the rotation based on the average of all
 half-selected edges and the extrude vector. The first rotation might go wrong
 on extruding parts of very irregular shapes, but in general it does it fine.
 Of course, single vertex clicking or entire shape clicking doesn't rotate.

---
 source/blender/src/editmesh_add.c | 50 +++++++++++++++++++++++++++----
 1 file changed, 45 insertions(+), 5 deletions(-)

diff --git a/source/blender/src/editmesh_add.c b/source/blender/src/editmesh_add.c
index 445c3d6ddfe..d27836033ec 100644
--- a/source/blender/src/editmesh_add.c
+++ b/source/blender/src/editmesh_add.c
@@ -155,23 +155,63 @@ void add_click_mesh(void)
 
 	/* call extrude? */
 	if(done) {
-		float vec[3];
+		EditEdge *eed;
+		float vec[3], cent[3], mat[3][3];
 		float nor[3]= {0.0, 0.0, 0.0};
 		
+		/* check for edges that are half selected, use for rotation */
+		done= 0;
+		for(eed= em->edges.first; eed; eed= eed->next) {
+			if( (eed->v1->f & SELECT)+(eed->v2->f & SELECT) == SELECT ) {
+				if(eed->v1->f & SELECT) VecSubf(vec, eed->v1->co, eed->v2->co);
+				else VecSubf(vec, eed->v2->co, eed->v1->co);
+				VecAddf(nor, nor, vec);
+				done= 1;
+			}
+		}
+		if(done) Normalise(nor);
+		
 		/* centre */
-		VecAddf(min, min, max);
-		VecMulf(min, 0.5f);
-		VECCOPY(vec, min);
+		VecAddf(cent, min, max);
+		VecMulf(cent, 0.5f);
+		VECCOPY(min, cent);
 		
 		Mat4MulVecfl(G.obedit->obmat, min);	// view space
 		get_view_aligned_coordinate(min);
 		Mat4Invert(G.obedit->imat, G.obedit->obmat); 
 		Mat4MulVecfl(G.obedit->imat, min); // back in object space
 		
-		VecSubf(min, min, vec);
+		VecSubf(min, min, cent);
+		
+		/* calculate rotation */
+		Mat3One(mat);
+		if(done) {
+			float dot;
+			
+			VECCOPY(vec, min);
+			Normalise(vec);
+			dot= INPR(vec, nor);
+
+			if( fabs(dot)<0.999) {
+				float cross[3], si, q1[4];
+				
+				Crossf(cross, nor, vec);
+				Normalise(cross);
+				dot= 0.5f*saacos(dot);
+				si= (float)sin(dot);
+				q1[0]= (float)cos(dot);
+				q1[1]= cross[0]*si;
+				q1[2]= cross[1]*si;
+				q1[3]= cross[2]*si;
+				
+				QuatToMat3(q1, mat);
+			}
+		}
 		
 		extrudeflag(SELECT, nor);
+		rotateflag(SELECT, cent, mat);
 		translateflag(SELECT, min);
+		
 		recalc_editnormals();
 	}
 	else {