* Patch #6877: Zoom to Mouse Position

by Fahrezal Effendi (exavolt)

This adds an additional preference to the view and controls section, which uses the mouse's position as the centre of the zoom when zooming in the 3D View with Ctrl-MMB or the mouse wheel. It's very nice for big scenes, thanks Fahrezal!

A nice todo would be to add this for 2D views as well.

1 files changed, 53 insertions, 5 deletions

diff --git a/source/blender/src/view.c b/source/blender/src/view.c
index 9b4f65fbc81..4ddd6d71dea 100644
--- a/source/blender/src/view.c
+++ b/source/blender/src/view.c
@@ -543,7 +543,7 @@ void viewmove(int mode)
 	float reverse, oldquat[4], q1[4], si, phi, dist0;
 	float ofs[3], obofs[3]= {0.0f, 0.0f, 0.0f};
 	int firsttime=1;
-	short mvalball[2], mval[2], mvalo[2];
+	short mvalball[2], mval[2], mvalo[2], mval_area[2];
 	short use_sel = 0;
 	short preview3d_event= 1;
 	
@@ -561,6 +561,7 @@ void viewmove(int mode)
 	
 	QUATCOPY(oldquat, G.vd->viewquat);
 	
+	getmouseco_areawin(mval_area);	/* for zoom to mouse loc */
 	getmouseco_sc(mvalo);		/* work with screen coordinates because of trackball function */
 	mvalball[0]= mvalo[0];			/* needed for turntable to work */
 	mvalball[1]= mvalo[1];
@@ -733,9 +734,10 @@ void viewmove(int mode)
 				}
 			}
 			else if(mode==2) {
+				float zfac=1.0;
 				if(U.viewzoom==USER_ZOOM_CONT) {
 					// oldstyle zoom
-					G.vd->dist*= 1.0+(float)(mvalo[0]-mval[0]+mvalo[1]-mval[1])/1000.0;
+					zfac = 1.0+(float)(mvalo[0]-mval[0]+mvalo[1]-mval[1])/1000.0;
 				}
 				else if(U.viewzoom==USER_ZOOM_SCALE) {
 					int ctr[2], len1, len2;
@@ -747,14 +749,17 @@ void viewmove(int mode)
 					len1 = (int)sqrt((ctr[0] - mval[0])*(ctr[0] - mval[0]) + (ctr[1] - mval[1])*(ctr[1] - mval[1])) + 5;
 					len2 = (int)sqrt((ctr[0] - mvalo[0])*(ctr[0] - mvalo[0]) + (ctr[1] - mvalo[1])*(ctr[1] - mvalo[1])) + 5;
 					
-					G.vd->dist= dist0 * ((float)len2/len1);
+					zfac = dist0 * ((float)len2/len1) / G.vd->dist;
 				}
 				else {	/* USER_ZOOM_DOLLY */
 					float len1 = (curarea->winrct.ymax - mval[1]) + 5;
 					float len2 = (curarea->winrct.ymax - mvalo[1]) + 5;
-					
-					G.vd->dist= dist0 * (2.0*((len2/len1)-1.0) + 1.0);
+					zfac = dist0 * (2.0*((len2/len1)-1.0) + 1.0) / G.vd->dist;
 				}
+
+				if(zfac != 1.0 && zfac*G.vd->dist > 0.001*G.vd->grid && 
+					zfac*G.vd->dist < 10.0*G.vd->far)
+					view_zoom_mouseloc(zfac, mval_area);
 				
 				/* these limits are in toets.c too */
 				if(G.vd->dist<0.001*G.vd->grid) G.vd->dist= 0.001*G.vd->grid;
@@ -804,6 +809,49 @@ void viewmove(int mode)
 		BIF_view3d_previewrender_signal(curarea, PR_PROJECTED);
 
 }
+ 
+void view_zoom_mouseloc(float dfac, short *mouseloc)
+{
+	if(U.uiflag & USER_ZOOM_TO_MOUSEPOS) {
+		short vb[2];
+		float dvec[3];
+		float tvec[3];
+		float tpos[3];
+		float new_dist;
+
+		/* find the current window width and height */
+		vb[0] = G.vd->area->winx;
+		vb[1] = G.vd->area->winy;
+		
+		tpos[0] = -G.vd->ofs[0];
+		tpos[1] = -G.vd->ofs[1];
+		tpos[2] = -G.vd->ofs[2];
+
+		/* Project cursor position into 3D space */
+		initgrabz(tpos[0], tpos[1], tpos[2]);
+		window_to_3d(dvec, mouseloc[0]-vb[0]/2, mouseloc[1]-vb[1]/2);
+
+		/* Calculate view target position for dolly */
+		tvec[0] = -(tpos[0] + dvec[0]);
+		tvec[1] = -(tpos[1] + dvec[1]);
+		tvec[2] = -(tpos[2] + dvec[2]);
+
+		/* Offset to target position and dolly */
+		new_dist = G.vd->dist * dfac;
+		
+		VECCOPY(G.vd->ofs, tvec);
+		G.vd->dist = new_dist;
+		
+		/* Calculate final offset */
+		dvec[0] = tvec[0] + dvec[0] * dfac;
+		dvec[1] = tvec[1] + dvec[1] * dfac;
+		dvec[2] = tvec[2] + dvec[2] * dfac;
+		
+		VECCOPY(G.vd->ofs, dvec);
+	} else {
+		G.vd->dist *= dfac;
+	}
+}
 
 /* Gets the lens and clipping values from a camera of lamp type object */
 void object_view_settings(Object *ob, float *lens, float *clipsta, float *clipend)