==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

3 files changed, 110 insertions, 32 deletions

diff --git a/source/blender/src/buttons_editing.c b/source/blender/src/buttons_editing.c
index affa06ae6b2..24964b30ce9 100644
--- a/source/blender/src/buttons_editing.c
+++ b/source/blender/src/buttons_editing.c
@@ -1604,7 +1604,7 @@ static void draw_modifier(uiBlock *block, Object *ob, ModifierData *md, int *xco
 		} else if (md->type==eModifierType_Build) {
 			height = 86;
 		} else if (md->type==eModifierType_Mirror) {
-			height = 67;
+			height = 86;
 		} else if (md->type==eModifierType_EdgeSplit) {
 			EdgeSplitModifierData *emd = (EdgeSplitModifierData*) md;
 			height = 48;
@@ -1728,6 +1728,11 @@ static void draw_modifier(uiBlock *block, Object *ob, ModifierData *md, int *xco
 			             &mmd->flag, 0, 0, 0, 0,
 			             "Mirror the V texture coordinate around "
 			             "the 0.5 point");
+			uiDefIDPoinBut(block, test_obpoin_but, ID_OB, B_CHANGEDEP,
+			               "Ob: ", lx, (cy -= 19), buttonWidth, 19,
+			               &mmd->mirror_ob,
+			               "Object to use as mirrot");
+
 		} else if (md->type==eModifierType_EdgeSplit) {
 			EdgeSplitModifierData *emd = (EdgeSplitModifierData*) md;
 			uiDefButBitI(block, TOG, MOD_EDGESPLIT_FROMANGLE,
diff --git a/source/blender/src/editmesh_lib.c b/source/blender/src/editmesh_lib.c
index 14a522bdbff..d9b8fa93eb9 100644
--- a/source/blender/src/editmesh_lib.c
+++ b/source/blender/src/editmesh_lib.c
@@ -1142,22 +1142,38 @@ static short extrudeflag_edge(short flag, float *nor)
 			MirrorModifierData *mmd = (MirrorModifierData*) md;	
 		
 			if(mmd->flag & MOD_MIR_CLIPPING) {
+				float mtx[4][4];
+				if (mmd->mirror_ob) {
+					float imtx[4][4];
+					Mat4Invert(imtx, mmd->mirror_ob->obmat);
+					Mat4MulMat4(mtx, G.obedit->obmat, imtx);
+				}
+
 				for (eed= em->edges.first; eed; eed= eed->next) {
 					if(eed->f2 == 1) {
+						float co1[3], co2[3];
+
+						VecCopyf(co1, eed->v1->co);
+						VecCopyf(co2, eed->v2->co);
+
+						if (mmd->mirror_ob) {
+							VecMat4MulVecfl(co1, mtx, co1);
+							VecMat4MulVecfl(co2, mtx, co2);
+						}
 
 						if (mmd->flag & MOD_MIR_AXIS_X)
-							if ( (fabs(eed->v1->co[0]) < mmd->tolerance) &&
-								 (fabs(eed->v2->co[0]) < mmd->tolerance) )
+							if ( (fabs(co1[0]) < mmd->tolerance) &&
+								 (fabs(co2[0]) < mmd->tolerance) )
 								++eed->f2;
 
 						if (mmd->flag & MOD_MIR_AXIS_Y)
-							if ( (fabs(eed->v1->co[1]) < mmd->tolerance) &&
-								 (fabs(eed->v2->co[1]) < mmd->tolerance) )
+							if ( (fabs(co1[1]) < mmd->tolerance) &&
+								 (fabs(co2[1]) < mmd->tolerance) )
 								++eed->f2;
 
 						if (mmd->flag & MOD_MIR_AXIS_Z)
-							if ( (fabs(eed->v1->co[2]) < mmd->tolerance) &&
-								 (fabs(eed->v2->co[2]) < mmd->tolerance) )
+							if ( (fabs(co1[2]) < mmd->tolerance) &&
+								 (fabs(co2[2]) < mmd->tolerance) )
 								++eed->f2;
 					}
 				}
@@ -1408,21 +1424,37 @@ short extrudeflag_vert(short flag, float *nor)
 			MirrorModifierData *mmd = (MirrorModifierData*) md;	
 		
 			if(mmd->flag & MOD_MIR_CLIPPING) {
+				float mtx[4][4];
+				if (mmd->mirror_ob) {
+					float imtx[4][4];
+					Mat4Invert(imtx, mmd->mirror_ob->obmat);
+					Mat4MulMat4(mtx, G.obedit->obmat, imtx);
+				}
+
 				for (eed= em->edges.first; eed; eed= eed->next) {
 					if(eed->f2 == 2) {
+						float co1[3], co2[3];
+
+						VecCopyf(co1, eed->v1->co);
+						VecCopyf(co2, eed->v2->co);
+
+						if (mmd->mirror_ob) {
+							VecMat4MulVecfl(co1, mtx, co1);
+							VecMat4MulVecfl(co2, mtx, co2);
+						}
 
 						if (mmd->flag & MOD_MIR_AXIS_X)
-							if ( (fabs(eed->v1->co[0]) < mmd->tolerance) &&
-								 (fabs(eed->v2->co[0]) < mmd->tolerance) )
+							if ( (fabs(co1[0]) < mmd->tolerance) &&
+								 (fabs(co2[0]) < mmd->tolerance) )
 								++eed->f2;
 
 						if (mmd->flag & MOD_MIR_AXIS_Y)
-							if ( (fabs(eed->v1->co[1]) < mmd->tolerance) &&
-								 (fabs(eed->v2->co[1]) < mmd->tolerance) )
+							if ( (fabs(co1[1]) < mmd->tolerance) &&
+								 (fabs(co2[1]) < mmd->tolerance) )
 								++eed->f2;
 						if (mmd->flag & MOD_MIR_AXIS_Z)
-							if ( (fabs(eed->v1->co[2]) < mmd->tolerance) &&
-								 (fabs(eed->v2->co[2]) < mmd->tolerance) )
+							if ( (fabs(co1[2]) < mmd->tolerance) &&
+								 (fabs(co2[2]) < mmd->tolerance) )
 								++eed->f2;
 					}
 				}
diff --git a/source/blender/src/transform_generics.c b/source/blender/src/transform_generics.c
index bf9de8d4e3f..72937fb10b6 100644
--- a/source/blender/src/transform_generics.c
+++ b/source/blender/src/transform_generics.c
@@ -154,6 +154,7 @@ static void clipMirrorModifier(TransInfo *t, Object *ob)
 			MirrorModifierData *mmd = (MirrorModifierData*) md;	
 		
 			if(mmd->flag & MOD_MIR_CLIPPING) {
+				axis = 0;
 				if(mmd->flag & MOD_MIR_AXIS_X) {
 					axis |= 1;
 					tolerance[0] = mmd->tolerance;
@@ -166,28 +167,68 @@ static void clipMirrorModifier(TransInfo *t, Object *ob)
 					axis |= 4;
 					tolerance[2] = mmd->tolerance;
 				}
-			}
-		}
-	}
-	if (axis) {
-		TransData *td = t->data;
-		int i;
+				if (axis) {
+					float mtx[4][4], imtx[4][4];
+					int i;
+					TransData *td = t->data;
 		
-		for(i = 0 ; i < t->total; i++, td++) {
-			if (td->flag & TD_NOACTION)
-				break;
-			if (td->loc==NULL)
-				break;
+					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 < t->total; i++, td++) {
+						int clip;
+						float loc[3], iloc[3];
+
+						if (td->flag & TD_NOACTION)
+							break;
+						if (td->loc==NULL)
+							break;
 			
-			if(axis & 1) {
-				if(fabs(td->iloc[0])<=tolerance[0] || td->loc[0]*td->iloc[0]<0.0f) td->loc[0]= 0.0f;
-			}
+						VecCopyf(loc,  td->loc);
+						VecCopyf(iloc, td->iloc);
+
+						if (mmd->mirror_ob) {
+							VecMat4MulVecfl(loc, mtx, loc);
+							VecMat4MulVecfl(iloc, mtx, iloc);
+						}
+
+						clip = 0;
+						if(axis & 1) {
+							if(fabs(iloc[0])<=tolerance[0] || 
+							   loc[0]*iloc[0]<0.0f) {
+								loc[0]= 0.0f;
+								clip = 1;
+							}
+						}
 			
-			if(axis & 2) {
-				if(fabs(td->iloc[1])<=tolerance[1] || td->loc[1]*td->iloc[1]<0.0f) td->loc[1]= 0.0f;
-			}
-			if(axis & 4) {
-				if(fabs(td->iloc[2])<=tolerance[2] || td->loc[2]*td->iloc[2]<0.0f) td->loc[2]= 0.0f;
+						if(axis & 2) {
+							if(fabs(iloc[1])<=tolerance[1] || 
+							   loc[1]*iloc[1]<0.0f) {
+								loc[1]= 0.0f;
+								clip = 1;
+							}
+						}
+						if(axis & 4) {
+							if(fabs(iloc[2])<=tolerance[2] || 
+							   loc[2]*iloc[2]<0.0f) {
+								loc[2]= 0.0f;
+								clip = 1;
+							}
+						}
+						if (clip) {
+							if (mmd->mirror_ob) {
+								VecMat4MulVecfl(loc, imtx, loc);
+							}
+							VecCopyf(td->loc, loc);
+						}
+					}
+				}
+
 			}
 		}
 	}