==Mirror Modifier==

Support for using the axes of a different object as the line of mirror
symmetry for a mirror modifier. As a nice consequence, this allows
"clipping" to arbitrary planes in editmode.

A fun example of using a couple of mirror modifiers and an array
modifier to easily make a nice flower type model is here:

http://bebop.cns.ualberta.ca/~cwant/chocolateC05.blend

1 files changed, 64 insertions, 11 deletions

diff --git a/source/blender/blenkernel/intern/modifier.c b/source/blender/blenkernel/intern/modifier.c
index 9c4280166ec..c2f3880ec19 100644
--- a/source/blender/blenkernel/intern/modifier.c
+++ b/source/blender/blenkernel/intern/modifier.c
@@ -1230,6 +1230,7 @@ static void mirrorModifier_initData(ModifierData *md)
 
 	mmd->flag |= MOD_MIR_AXIS_X;
 	mmd->tolerance = 0.001;
+	mmd->mirror_ob = NULL;
 }
 
 static void mirrorModifier_copyData(ModifierData *md, ModifierData *target)
@@ -1240,12 +1241,37 @@ static void mirrorModifier_copyData(ModifierData *md, ModifierData *target)
 	tmmd->axis = mmd->axis;
 	tmmd->flag = mmd->flag;
 	tmmd->tolerance = mmd->tolerance;
+	tmmd->mirror_ob = mmd->mirror_ob;;
+}
+
+static void mirrorModifier_foreachObjectLink(
+                ModifierData *md, Object *ob,
+                void (*walk)(void *userData, Object *ob, Object **obpoin),
+                void *userData)
+{
+	MirrorModifierData *mmd = (MirrorModifierData*) md;
+
+	walk(userData, ob, &mmd->mirror_ob);
+}
+
+static void mirrorModifier_updateDepgraph(ModifierData *md, DagForest *forest,
+										  Object *ob, DagNode *obNode)
+{
+	MirrorModifierData *mmd = (MirrorModifierData*) md;
+
+	if(mmd->mirror_ob) {
+		DagNode *latNode = dag_get_node(forest, mmd->mirror_ob);
+
+		dag_add_relation(forest, latNode, obNode,
+		                 DAG_RL_DATA_DATA | DAG_RL_OB_DATA);
+	}
 }
 
 static DerivedMesh *doMirrorOnAxis(MirrorModifierData *mmd,
-						   DerivedMesh *dm,
-						   int initFlags,
-						   int axis)
+								   Object *ob,
+								   DerivedMesh *dm,
+								   int initFlags,
+								   int axis)
 {
 	int i;
 	float tolerance = mmd->tolerance;
@@ -1255,6 +1281,7 @@ static DerivedMesh *doMirrorOnAxis(MirrorModifierData *mmd,
 	int maxEdges = dm->getNumEdges(dm);
 	int maxFaces = dm->getNumFaces(dm);
 	int (*indexMap)[2];
+	float mtx[4][4], imtx[4][4];
 
 	numVerts = numEdges = numFaces = 0;
 
@@ -1262,13 +1289,28 @@ static DerivedMesh *doMirrorOnAxis(MirrorModifierData *mmd,
 
 	result = CDDM_from_template(dm, maxVerts * 2, maxEdges * 2, maxFaces * 2);
 
+	if (mmd->mirror_ob) {
+		float obinv[4][4];
+
+		Mat4Invert(obinv, mmd->mirror_ob->obmat);
+		Mat4MulMat4(mtx, ob->obmat, obinv);
+		Mat4Invert(imtx, mtx);
+	}
+
 	for(i = 0; i < maxVerts; i++) {
 		MVert inMV;
 		MVert *mv = CDDM_get_vert(result, numVerts);
 		int isShared;
+		float co[3];
 
 		dm->getVert(dm, i, &inMV);
-		isShared = ABS(inMV.co[axis])<=tolerance;
+
+		VecCopyf(co, inMV.co);
+
+		if (mmd->mirror_ob) {
+			VecMat4MulVecfl(co, mtx, co);
+		}
+		isShared = ABS(co[axis])<=tolerance;
 
 		/* Because the topology result (# of vertices) must be the same if
 		 * the mesh data is overridden by vertex cos, have to calc sharedness
@@ -1282,7 +1324,12 @@ static DerivedMesh *doMirrorOnAxis(MirrorModifierData *mmd,
 		indexMap[i][1] = !isShared;
 
 		if(isShared) {
-			mv->co[axis] = 0;
+			co[axis] = 0;
+			if (mmd->mirror_ob) {
+				VecMat4MulVecfl(co, imtx, co);
+			}
+			VecCopyf(mv->co, co);
+			
 			mv->flag |= ME_VERT_MERGED;
 		} else {
 			MVert *mv2 = CDDM_get_vert(result, numVerts);
@@ -1291,7 +1338,11 @@ static DerivedMesh *doMirrorOnAxis(MirrorModifierData *mmd,
 			*mv2 = *mv;
 			numVerts++;
 
-			mv2->co[axis] = -mv2->co[axis];
+			co[axis] = -co[axis];
+			if (mmd->mirror_ob) {
+				VecMat4MulVecfl(co, imtx, co);
+			}
+			VecCopyf(mv2->co, co);
 		}
 	}
 
@@ -1385,23 +1436,23 @@ static DerivedMesh *doMirrorOnAxis(MirrorModifierData *mmd,
 }
 
 static DerivedMesh *mirrorModifier__doMirror(MirrorModifierData *mmd,
-                                             DerivedMesh *dm,
+											 Object *ob, DerivedMesh *dm,
                                              int initFlags)
 {
 	DerivedMesh *result = dm;
 
 	/* check which axes have been toggled and mirror accordingly */
 	if(mmd->flag & MOD_MIR_AXIS_X) {
-		result = doMirrorOnAxis(mmd, result, initFlags, 0);
+		result = doMirrorOnAxis(mmd, ob, result, initFlags, 0);
 	}
 	if(mmd->flag & MOD_MIR_AXIS_Y) {
 		DerivedMesh *tmp = result;
-		result = doMirrorOnAxis(mmd, result, initFlags, 1);
+		result = doMirrorOnAxis(mmd, ob, result, initFlags, 1);
 		if(tmp != dm) tmp->release(tmp); /* free intermediate results */
 	}
 	if(mmd->flag & MOD_MIR_AXIS_Z) {
 		DerivedMesh *tmp = result;
-		result = doMirrorOnAxis(mmd, result, initFlags, 2);
+		result = doMirrorOnAxis(mmd, ob, result, initFlags, 2);
 		if(tmp != dm) tmp->release(tmp); /* free intermediate results */
 	}
 
@@ -1415,7 +1466,7 @@ static DerivedMesh *mirrorModifier_applyModifier(
 	DerivedMesh *result;
 	MirrorModifierData *mmd = (MirrorModifierData*) md;
 
-	result = mirrorModifier__doMirror(mmd, derivedData, 0);
+	result = mirrorModifier__doMirror(mmd, ob, derivedData, 0);
 
 	CDDM_calc_normals(result);
 	
@@ -5313,6 +5364,8 @@ ModifierTypeInfo *modifierType_getInfo(ModifierType type)
 		             | eModifierTypeFlag_EnableInEditmode;
 		mti->initData = mirrorModifier_initData;
 		mti->copyData = mirrorModifier_copyData;
+		mti->foreachObjectLink = mirrorModifier_foreachObjectLink;
+		mti->updateDepgraph = mirrorModifier_updateDepgraph;
 		mti->applyModifier = mirrorModifier_applyModifier;
 		mti->applyModifierEM = mirrorModifier_applyModifierEM;