Little warming-up getting-feet-wet coding project. :)

Much wanted feature, to have paths with children having fixed distance
offsets from each other, for example to animate a train with wagons.

Solved it with Path option (Editing buttons curve) "PathDist Offs" which
interprets time-offsets of children as blender-unit offsets. The entire
animation system still works, but offsets are calculated based on distance,
even with a CurvePath without motion (speed curve horizontal).

http://download.blender.org/demo/test/pathdist.blend

Thanks to Bassam for kicking my ass!

4 files changed, 24 insertions, 8 deletions

diff --git a/source/blender/blenkernel/intern/object.c b/source/blender/blenkernel/intern/object.c
index ffc1dc36e69..e11ada6f6c2 100644
--- a/source/blender/blenkernel/intern/object.c
+++ b/source/blender/blenkernel/intern/object.c
@@ -992,12 +992,18 @@ void ob_parcurve(Object *ob, Object *par, float mat[][4])
 {
 	Curve *cu;
 	float q[4], vec[4], dir[3], *quat, x1, ctime;
+	float timeoffs= 0.0;
 	
 	Mat4One(mat);
 	
 	cu= par->data;
-	if(cu->path==0 || cu->path->data==0) calc_curvepath(par);
-	if(cu->path==0) return;
+	if(cu->path==NULL || cu->path->data==NULL) calc_curvepath(par);
+	if(cu->path==NULL) return;
+	
+	/* exception, timeoffset is regarded as distance offset */
+	if(cu->flag & CU_OFFS_PATHDIST) {
+		SWAP(float, timeoffs, ob->sf);
+	}
 	
 	/* catch exceptions: curve paths used as a duplicator */
 	if(enable_cu_speed) {
@@ -1014,7 +1020,16 @@ void ob_parcurve(Object *ob, Object *par, float mat[][4])
 		
 		CLAMP(ctime, 0.0, 1.0);
 	}
+	
+	/* time calculus is correct, now apply distance offset */
+	if(cu->flag & CU_OFFS_PATHDIST) {
+		ctime += timeoffs/cu->path->totdist;
 
+		/* restore */
+		SWAP(float, timeoffs, ob->sf);
+	}
+	
+	
 	/* vec: 4 items! */
  	if( where_on_path(par, ctime, vec, dir) ) {
 
diff --git a/source/blender/makesdna/DNA_curve_types.h b/source/blender/makesdna/DNA_curve_types.h
index 69ee9851cd7..0713f770dc4 100644
--- a/source/blender/makesdna/DNA_curve_types.h
+++ b/source/blender/makesdna/DNA_curve_types.h
@@ -176,6 +176,7 @@ typedef struct IpoCurve {
 #define CU_UV_ORCO		32
 #define CU_NOPUNOFLIP	64
 #define CU_STRETCH		128
+#define CU_OFFS_PATHDIST	256
 
 /* spacemode */
 #define CU_LEFT			0
diff --git a/source/blender/renderconverter/intern/convertBlenderScene.c b/source/blender/renderconverter/intern/convertBlenderScene.c
index 2b4803bfdec..5bdd0c36702 100644
--- a/source/blender/renderconverter/intern/convertBlenderScene.c
+++ b/source/blender/renderconverter/intern/convertBlenderScene.c
@@ -2952,9 +2952,6 @@ void RE_rotateBlenderScene(void)
 	MTC_Mat4Ortho(R.viewinv);
 	MTC_Mat4Invert(R.viewmat, R.viewinv);
 
-	/* not so neat: now the viewinv is not equal to viewmat. used for Texcos and such. Improve! */
-	//if(R.r.mode & R_ORTHO) R.viewmat[3][2]*= 100.0;
-
 	RE_setwindowclip(1,-1); /*  no jit:(-1) */
 
 	/* clear imat flags */
diff --git a/source/blender/src/buttons_editing.c b/source/blender/src/buttons_editing.c
index 371a2f9c94c..65829bd1e3f 100644
--- a/source/blender/src/buttons_editing.c
+++ b/source/blender/src/buttons_editing.c
@@ -1262,16 +1262,19 @@ static void editing_panel_curve_type(Object *ob, Curve *cu)
 		if(ob->type==OB_CURVE) {
 			extern float prlen;		// buttons_object.c, should be moved....
 			char str[32];
+			
+			sprintf(str, "%.4f", prlen);
+			uiDefBut(block, BUT, B_PRINTLEN,		"PrintLen",	600,135,75,19, 0, 0, 0, 0, 0, "");
+			uiDefBut(block, LABEL, 0, str,						675,135,75,19, 0, 1.0, 0, 0, 0, "");
+			
 			uiBlockBeginAlign(block);
 			uiDefButS(block, NUM, B_RECALCPATH, "PathLen:",			600,50,150,19, &cu->pathlen, 1.0, 9000.0, 0, 0, "If no speed Ipo was set, the amount of frames of the path");
 			uiDefButS(block, TOG|BIT|3, B_RECALCPATH, "CurvePath",	600,30,75,19 , &cu->flag, 0, 0, 0, 0, "Enables curve to become translation path");
 			uiDefButS(block, TOG|BIT|4, REDRAWVIEW3D, "CurveFollow",675,30,75,19, &cu->flag, 0, 0, 0, 0, "Makes curve path children to rotate along path");
 			uiDefButS(block, TOG|BIT|7, B_CURVECHECK, "CurveStretch", 600,10,150,19, &cu->flag, 0, 0, 0, 0, "Option for curve-deform: makes deformed child to stretch along entire path");
+			uiDefButS(block, TOG|BIT|8, REDRAWVIEW3D, "PathDist Offs", 600,-10,150,19, &cu->flag, 0, 0, 0, 0, "Children will use TimeOffs value as path distance offset");
 
 			uiBlockEndAlign(block);
-			sprintf(str, "%.4f", prlen);
-			uiDefBut(block, BUT, B_PRINTLEN,		"PrintLen",	600,-10,75,19, 0, 0, 0, 0, 0, "");
-			uiDefBut(block, LABEL, 0, str,						675,-10,75,19, 0, 1.0, 0, 0, 0, "");
 		}
 
 		uiBlockBeginAlign(block);