Fix #29743: Video sequencer wipe effect bug

Blur width used to be calculated quite strange depending on current angle.
Also, it used to be using wrong formula to calculate distance between
current point and boundary line which made blur width almost useless.

Now actual blur width is doesn't depend on angle and use corrected formula
for distance calculation which makes blur width slider behaves more
predictable.

This commit might make old files using wipe+blur be rendered a bit differently,
but don't think it's indeed issue because old behavior was crappy to setup
something useful so don't think this setup was used a lot.

1 files changed, 23 insertions, 37 deletions

diff --git a/source/blender/blenkernel/intern/seqeffects.c b/source/blender/blenkernel/intern/seqeffects.c
index 718b3144677..731f82e1b80 100644
--- a/source/blender/blenkernel/intern/seqeffects.c
+++ b/source/blender/blenkernel/intern/seqeffects.c
@@ -1574,7 +1574,6 @@ typedef struct WipeZone {
 	int flip;
 	int xo, yo;
 	int width;
-	float invwidth;
 	float pythangle;
 } WipeZone;
 
@@ -1585,33 +1584,25 @@ static void precalc_wipe_zone(WipeZone *wipezone, WipeVars *wipe, int xo, int yo
 	wipezone->xo = xo;
 	wipezone->yo = yo;
 	wipezone->width = (int)(wipe->edgeWidth*((xo+yo)/2.0f));
-	wipezone->pythangle = 1.0f/sqrtf(wipe->angle*wipe->angle + 1.0f);
-
-	if(wipe->wipetype == DO_SINGLE_WIPE)
-		wipezone->invwidth = 1.0f/wipezone->width;
-	else
-		wipezone->invwidth = 1.0f/(0.5f*wipezone->width);
+	wipezone->pythangle = 1.0f/sqrtf(wipezone->angle*wipezone->angle + 1.0f);
 }
 
 // This function calculates the blur band for the wipe effects
-static float in_band(WipeZone *wipezone,float width,float dist,float perc,int side,int dir)
+static float in_band(float width,float dist,int side,int dir)
 {
-	float t1,t2,alpha;
+	float alpha;
 
 	if(width == 0)
 		return (float)side;
-	
+
 	if(width < dist)
-		return side;
-	
-	t1 = dist * wipezone->invwidth;  //percentange of width that is
-	t2 = wipezone->invwidth;  //amount of alpha per % point
-	
+		return (float)side;
+
 	if(side == 1)
-		alpha = (t1*t2*100) + (1-perc); // add point's alpha contrib to current position in wipe
+		alpha = (dist+0.5*width) / (width);
 	else
-		alpha = (1-perc) - (t1*t2*100);
-	
+		alpha = (0.5*width-dist) / (width);
+
 	if(dir == 0)
 		alpha = 1-alpha;
 
@@ -1648,7 +1639,6 @@ float hyp3,hyp4,b4,b5
 	switch (wipe->wipetype) {
 		case DO_SINGLE_WIPE:
 			width = wipezone->width;
-			hwidth = width*0.5f;
 
 			if(angle == 0.0f) {
 				b1 = posy;
@@ -1669,15 +1659,15 @@ float hyp3,hyp4,b4,b5
 
 			if(wipe->forward) {
 				if(b1 < b2)
-					output = in_band(wipezone,width,hyp,facf0,1,1);
+					output = in_band(width,hyp,1,1);
 				else
-					output = in_band(wipezone,width,hyp,facf0,0,1);
+					output = in_band(width,hyp,0,1);
 			}
 			else {
 				if(b1 < b2)
-					output = in_band(wipezone,width,hyp,facf0,0,1);
+					output = in_band(width,hyp,0,1);
 				else
-					output = in_band(wipezone,width,hyp,facf0,1,1);
+					output = in_band(width,hyp,1,1);
 			}
 		break;
 
@@ -1700,27 +1690,23 @@ float hyp3,hyp4,b4,b5
 				b3 = (yo-posy*0.5f) - (-angle)*(xo-posx*0.5f);
 				b2 = y - (-angle)*x;
 
-				hyp = abs(angle*x+y+(-posy*0.5f-angle*posx*0.5f))*wipezone->pythangle;
-				hyp2 = abs(angle*x+y+(-(yo-posy*0.5f)-angle*(xo-posx*0.5f)))*wipezone->pythangle;
+				hyp = fabsf(angle*x+y+(-posy*0.5f-angle*posx*0.5f))*wipezone->pythangle;
+				hyp2 = fabsf(angle*x+y+(-(yo-posy*0.5f)-angle*(xo-posx*0.5f)))*wipezone->pythangle;
 			}
 
-			temp1 = xo*(1-facf0*0.5f)-xo*facf0*0.5f;
-			temp2 = yo*(1-facf0*0.5f)-yo*facf0*0.5f;
-			pointdist = sqrt(temp1*temp1 + temp2*temp2);
+			hwidth= MIN2(hwidth, fabsf(b3-b1)/2.0f);
 
 			if(b2 < b1 && b2 < b3 ){
-				if(hwidth < pointdist)
-					output = in_band(wipezone,hwidth,hyp,facf0,0,1);
+				output = in_band(hwidth,hyp,0,1);
 			} else if(b2 > b1 && b2 > b3 ){
-				if(hwidth < pointdist)
-					output = in_band(wipezone,hwidth,hyp2,facf0,0,1);	
+				output = in_band(hwidth,hyp2,0,1);
 			} else {
 				if(  hyp < hwidth && hyp2 > hwidth )
-					output = in_band(wipezone,hwidth,hyp,facf0,1,1);
+					output = in_band(hwidth,hyp,1,1);
 				else if( hyp > hwidth && hyp2 < hwidth )
-					  output = in_band(wipezone,hwidth,hyp2,facf0,1,1);
+					  output = in_band(hwidth,hyp2,1,1);
 				else
-					  output = in_band(wipezone,hwidth,hyp2,facf0,1,1) * in_band(wipezone,hwidth,hyp,facf0,1,1);
+					  output = in_band(hwidth,hyp2,1,1) * in_band(hwidth,hyp,1,1);
 			}
 			if(!wipe->forward)output = 1-output;
 		break;
@@ -1840,8 +1826,8 @@ float hyp3,hyp4,b4,b5
 			pointdist = sqrt(temp1*temp1 + temp1*temp1);
 
 			temp2 = sqrt((halfx-x)*(halfx-x) + (halfy-y)*(halfy-y));
-			if(temp2 > pointdist) output = in_band(wipezone,hwidth,fabs(temp2-pointdist),facf0,0,1);
-			else output = in_band(wipezone,hwidth,fabs(temp2-pointdist),facf0,1,1);
+			if(temp2 > pointdist) output = in_band(hwidth,fabs(temp2-pointdist),0,1);
+			else output = in_band(hwidth,fabs(temp2-pointdist),1,1);
 
 			if(!wipe->forward) output = 1-output;