Small addition to stretch minimize: with pad +/- or the wheel mouse

you can now blend between the original and minimized.

Stretch minimizing trades conformality (= perfect squares in checkerboard
texture) for a better sampling of the texture (= often not so well shaped
checkerboard), so it is useful to let the user find a balance between the
two.

source/blender/src/parametrizer.c

@@ -1135,6 +1135,19 @@ static void p_flush_uvs(PChart *chart)
 	}
 }
 
+static void p_flush_uvs_blend(PChart *chart, float blend)
+{
+	PEdge *e;
+	float invblend = 1.0f - blend;
+
+	for (e=(PEdge*)chart->edges->first; e; e=e->link.next) {
+		if (e->orig_uv) {
+			e->orig_uv[0] = blend*e->old_uv[0] + invblend*e->vert->uv[0];
+			e->orig_uv[1] = blend*e->old_uv[1] + invblend*e->vert->uv[1];
+		}
+	}
+}
+
 /* Exported */
 
 ParamHandle *param_construct_begin()
@@ -1620,6 +1633,7 @@ void param_stretch_begin(ParamHandle *handle)
 	phandle->state = PHANDLE_STATE_STRETCH;
 
 	phandle->rng = rng_new(31415926);
+	phandle->blend = 0.0f;
 
 	for (i = 0; i < phandle->ncharts; i++) {
 		chart = phandle->charts[i];
@@ -1636,6 +1650,28 @@ void param_stretch_begin(ParamHandle *handle)
 	}
 }
 
+void param_stretch_blend(ParamHandle *handle, float blend)
+{
+	PHandle *phandle = (PHandle*)handle;
+	PChart *chart;
+	int i;
+
+	param_assert(phandle->state == PHANDLE_STATE_STRETCH);
+
+	if (phandle->blend != blend) {
+		phandle->blend = blend;
+
+		for (i = 0; i < phandle->ncharts; i++) {
+			chart = phandle->charts[i];
+
+			if (blend == 0.0f)
+				p_flush_uvs(chart);
+			else
+				p_flush_uvs_blend(chart, blend);
+		}
+	}
+}
+
 void param_stretch_iter(ParamHandle *handle)
 {
 	PHandle *phandle = (PHandle*)handle;
@@ -1648,7 +1684,11 @@ void param_stretch_iter(ParamHandle *handle)
 		chart = phandle->charts[i];
 
 		p_chart_stretch_minimize(chart, phandle->rng);
+
+		if (phandle->blend == 0.0f)
 			p_flush_uvs(chart);
+		else
+			p_flush_uvs_blend(chart, phandle->blend);
 	}
 }
 

source/blender/src/parametrizer.h

@@ -59,6 +59,7 @@ void param_lscm_end(ParamHandle *handle);
 /* Stretch */
 
 void param_stretch_begin(ParamHandle *handle);
+void param_stretch_blend(ParamHandle *handle, float blend);
 void param_stretch_iter(ParamHandle *handle);
 void param_stretch_end(ParamHandle *handle, ParamBool restore);
 

source/blender/src/parametrizer_intern.h

@@ -180,6 +180,7 @@ typedef struct PHandle {
 	MemArena *arena;
 	PBool implicit;
 	RNG *rng;
+	float blend;
 } PHandle;
 
 #endif /*__PARAMETRIZER_INTERN_H__*/

source/blender/src/unwrapper.c

@@ -1457,7 +1457,7 @@ void minimize_stretch_tface_uv(void)
 	Mesh *me;
 	ParamHandle *handle;
 	double lasttime;
-	short doit = 1, val;
+	short doit = 1, escape = 0, val, blend = 0;
 	unsigned short event = 0;
 	
 	me = get_mesh(OBACT);
@@ -1474,15 +1474,47 @@ void minimize_stretch_tface_uv(void)
 
 		while (qtest()) {
 			event= extern_qread(&val);
-			if (val && (event==ESCKEY || event==RETKEY || event==PADENTER))
+
+			if (val) {
+				switch (event) {
+					case ESCKEY:
+						escape = 1;
+					case RETKEY:
+					case PADENTER:
 						doit = 0;
+						break;
+					case PADPLUSKEY:
+					case WHEELUPMOUSE:
+						if (blend < 10) {
+							blend++;
+							param_stretch_blend(handle, blend*0.1f);
+							lasttime = 0.0f;
+						}
+						break;
+					case PADMINUS:
+					case WHEELDOWNMOUSE:
+						if (blend > 0) {
+							blend--;
+							param_stretch_blend(handle, blend*0.1f);
+							lasttime = 0.0f;
+						}
+						break;
+				}
+			}
+			else if ((event == LEFTMOUSE) || (event == RIGHTMOUSE)) {
+					escape = (event == RIGHTMOUSE);
+					doit = 0;
+			}
 		}
 		
 		if (!doit)
 			break;
 
 		if (PIL_check_seconds_timer() - lasttime > 0.5) {
-			headerprint("Enter to finish. Escape to cancel.");
+			char str[100];
+
+			sprintf(str, "Stretch minimize. Blend %.2f.", blend*0.1f);
+			headerprint(str);
 
 			lasttime = PIL_check_seconds_timer();
 			if(G.sima->lock) force_draw_plus(SPACE_VIEW3D, 0);
@@ -1490,7 +1522,7 @@ void minimize_stretch_tface_uv(void)
 		}
 	}
 
-	param_stretch_end(handle, event==ESCKEY);
+	param_stretch_end(handle, escape);
 
 	param_delete(handle);