Moved vectorblur code from render to compositor

In preparation of the removal of blender internal render we
moved the vectorblur code that was placed in the render package
(legacy) to the compositor. The compositor is only using this
code even the blender internal renderer did not use the code at
all.

1 files changed, 707 insertions, 9 deletions

diff --git a/source/blender/compositor/operations/COM_VectorBlurOperation.cpp b/source/blender/compositor/operations/COM_VectorBlurOperation.cpp
index 36f06e92436..bccfe025089 100644
--- a/source/blender/compositor/operations/COM_VectorBlurOperation.cpp
+++ b/source/blender/compositor/operations/COM_VectorBlurOperation.cpp
@@ -20,16 +20,30 @@
  *		Monique Dewanchand
  */
 
-#include "COM_VectorBlurOperation.h"
-#include "BLI_math.h"
-
+#include <string.h>
 #include "MEM_guardedalloc.h"
-
-// use the implementation of blender internal renderer to calculate the vector blur.
+#include "BLI_math.h"
 extern "C" {
-#  include "RE_pipeline.h"
+	#include "BLI_jitter_2d.h"
 }
+#include "COM_VectorBlurOperation.h"
 
+
+/* Defined */
+#define PASS_VECTOR_MAX	10000.0f
+
+/* Forward declarations */
+struct ZSpan;
+struct DrawBufPixel;
+void zbuf_accumulate_vecblur(
+		NodeBlurData *nbd, int xsize, int ysize, float *newrect,
+		const float *imgrect, float *vecbufrect, const float *zbufrect);
+void zbuf_alloc_span(ZSpan *zspan, int rectx, int recty, float clipcrop);
+void zbuf_free_span(ZSpan *zspan);
+void antialias_tagbuf(int xsize, int ysize, char *rectmove);
+
+
+/* VectorBlurOperation */
 VectorBlurOperation::VectorBlurOperation() : NodeOperation()
 {
 	this->addInputSocket(COM_DT_COLOR);
@@ -51,7 +65,7 @@ void VectorBlurOperation::initExecution()
 	this->m_inputSpeedProgram = getInputSocketReader(2);
 	this->m_cachedInstance = NULL;
 	QualityStepHelper::initExecution(COM_QH_INCREASE);
-	
+
 }
 
 void VectorBlurOperation::executePixel(float output[4], int x, int y, void *data)
@@ -77,7 +91,7 @@ void *VectorBlurOperation::initializeTileData(rcti *rect)
 	if (this->m_cachedInstance) {
 		return this->m_cachedInstance;
 	}
-	
+
 	lockMutex();
 	if (this->m_cachedInstance == NULL) {
 		MemoryBuffer *tile = (MemoryBuffer *)this->m_inputImageProgram->initializeTileData(rect);
@@ -114,6 +128,690 @@ void VectorBlurOperation::generateVectorBlur(float *data, MemoryBuffer *inputIma
 	blurdata.minspeed = this->m_settings->minspeed;
 	blurdata.curved = this->m_settings->curved;
 	blurdata.fac = this->m_settings->fac;
-	RE_zbuf_accumulate_vecblur(&blurdata, this->getWidth(), this->getHeight(), data, inputImage->getBuffer(), inputSpeed->getBuffer(), inputZ->getBuffer());
+	zbuf_accumulate_vecblur(&blurdata, this->getWidth(), this->getHeight(), data, inputImage->getBuffer(), inputSpeed->getBuffer(), inputZ->getBuffer());
 	return;
 }
+
+/* ****************** Spans ******************************* */
+/* span fill in method, is also used to localize data for zbuffering */
+typedef struct ZSpan {
+	/* range for clipping */
+	int rectx, recty;
+
+	/* actual filled in range */
+	int miny1, maxy1, miny2, maxy2;
+	/* vertex pointers detect min/max range in */
+	const float *minp1, *maxp1, *minp2, *maxp2;
+	float *span1, *span2;
+
+	/* transform from hoco to zbuf co */
+	float zmulx, zmuly, zofsx, zofsy;
+
+	int *rectz;
+	DrawBufPixel* rectdraw;
+	float clipcrop;
+
+} ZSpan;
+
+/* each zbuffer has coordinates transformed to local rect coordinates, so we can simply clip */
+void zbuf_alloc_span(ZSpan *zspan, int rectx, int recty, float clipcrop)
+{
+	memset(zspan, 0, sizeof(ZSpan));
+
+	zspan->rectx= rectx;
+	zspan->recty= recty;
+
+	zspan->span1= (float*)MEM_mallocN(recty*sizeof(float), "zspan");
+	zspan->span2= (float*)MEM_mallocN(recty*sizeof(float), "zspan");
+
+	zspan->clipcrop= clipcrop;
+}
+
+void zbuf_free_span(ZSpan *zspan)
+{
+	if (zspan) {
+		if (zspan->span1) MEM_freeN(zspan->span1);
+		if (zspan->span2) MEM_freeN(zspan->span2);
+		zspan->span1= zspan->span2= NULL;
+	}
+}
+
+/* reset range for clipping */
+static void zbuf_init_span(ZSpan *zspan)
+{
+	zspan->miny1= zspan->miny2= zspan->recty+1;
+	zspan->maxy1= zspan->maxy2= -1;
+	zspan->minp1= zspan->maxp1= zspan->minp2= zspan->maxp2= NULL;
+}
+
+static void zbuf_add_to_span(ZSpan *zspan, const float v1[2], const float v2[2])
+{
+	const float *minv, *maxv;
+	float *span;
+	float xx1, dx0, xs0;
+	int y, my0, my2;
+
+	if (v1[1]<v2[1]) {
+		minv= v1; maxv= v2;
+	}
+	else {
+		minv= v2; maxv= v1;
+	}
+
+	my0= ceil(minv[1]);
+	my2= floor(maxv[1]);
+
+	if (my2<0 || my0>= zspan->recty) return;
+
+	/* clip top */
+	if (my2>=zspan->recty) my2= zspan->recty-1;
+	/* clip bottom */
+	if (my0<0) my0= 0;
+
+	if (my0>my2) return;
+	/* if (my0>my2) should still fill in, that way we get spans that skip nicely */
+
+	xx1= maxv[1]-minv[1];
+	if (xx1>FLT_EPSILON) {
+		dx0= (minv[0]-maxv[0])/xx1;
+		xs0= dx0*(minv[1]-my2) + minv[0];
+	}
+	else {
+		dx0 = 0.0f;
+		xs0 = min_ff(minv[0], maxv[0]);
+	}
+
+	/* empty span */
+	if (zspan->maxp1 == NULL) {
+		span= zspan->span1;
+	}
+	else {	/* does it complete left span? */
+		if ( maxv == zspan->minp1 || minv==zspan->maxp1) {
+			span= zspan->span1;
+		}
+		else {
+			span= zspan->span2;
+		}
+	}
+
+	if (span==zspan->span1) {
+//		printf("left span my0 %d my2 %d\n", my0, my2);
+		if (zspan->minp1==NULL || zspan->minp1[1] > minv[1] ) {
+			zspan->minp1= minv;
+		}
+		if (zspan->maxp1==NULL || zspan->maxp1[1] < maxv[1] ) {
+			zspan->maxp1= maxv;
+		}
+		if (my0<zspan->miny1) zspan->miny1= my0;
+		if (my2>zspan->maxy1) zspan->maxy1= my2;
+	}
+	else {
+//		printf("right span my0 %d my2 %d\n", my0, my2);
+		if (zspan->minp2==NULL || zspan->minp2[1] > minv[1] ) {
+			zspan->minp2= minv;
+		}
+		if (zspan->maxp2==NULL || zspan->maxp2[1] < maxv[1] ) {
+			zspan->maxp2= maxv;
+		}
+		if (my0<zspan->miny2) zspan->miny2= my0;
+		if (my2>zspan->maxy2) zspan->maxy2= my2;
+	}
+
+	for (y=my2; y>=my0; y--, xs0+= dx0) {
+		/* xs0 is the xcoord! */
+		span[y]= xs0;
+	}
+}
+
+/* ******************** VECBLUR ACCUM BUF ************************* */
+
+typedef struct DrawBufPixel {
+	const float *colpoin;
+	float alpha;
+} DrawBufPixel;
+
+
+static void zbuf_fill_in_rgba(ZSpan *zspan, DrawBufPixel *col, float *v1, float *v2, float *v3, float *v4)
+{
+	DrawBufPixel *rectpofs, *rp;
+	double zxd, zyd, zy0, zverg;
+	float x0, y0, z0;
+	float x1, y1, z1, x2, y2, z2, xx1;
+	const float *span1, *span2;
+	float *rectzofs, *rz;
+	int x, y;
+	int sn1, sn2, rectx, my0, my2;
+
+	/* init */
+	zbuf_init_span(zspan);
+
+	/* set spans */
+	zbuf_add_to_span(zspan, v1, v2);
+	zbuf_add_to_span(zspan, v2, v3);
+	zbuf_add_to_span(zspan, v3, v4);
+	zbuf_add_to_span(zspan, v4, v1);
+
+	/* clipped */
+	if (zspan->minp2==NULL || zspan->maxp2==NULL) return;
+
+	my0 = max_ii(zspan->miny1, zspan->miny2);
+	my2 = min_ii(zspan->maxy1, zspan->maxy2);
+
+	//	printf("my %d %d\n", my0, my2);
+	if (my2<my0) return;
+
+	/* ZBUF DX DY, in floats still */
+	x1= v1[0]- v2[0];
+	x2= v2[0]- v3[0];
+	y1= v1[1]- v2[1];
+	y2= v2[1]- v3[1];
+	z1= v1[2]- v2[2];
+	z2= v2[2]- v3[2];
+	x0= y1*z2-z1*y2;
+	y0= z1*x2-x1*z2;
+	z0= x1*y2-y1*x2;
+
+	if (z0==0.0f) return;
+
+	xx1= (x0*v1[0] + y0*v1[1])/z0 + v1[2];
+
+	zxd= -(double)x0/(double)z0;
+	zyd= -(double)y0/(double)z0;
+	zy0= ((double)my2)*zyd + (double)xx1;
+
+	/* start-offset in rect */
+	rectx= zspan->rectx;
+	rectzofs= (float *)(zspan->rectz + rectx*my2);
+	rectpofs= ((DrawBufPixel *)zspan->rectdraw) + rectx*my2;
+
+	/* correct span */
+	sn1= (my0 + my2)/2;
+	if (zspan->span1[sn1] < zspan->span2[sn1]) {
+		span1= zspan->span1+my2;
+		span2= zspan->span2+my2;
+	}
+	else {
+		span1= zspan->span2+my2;
+		span2= zspan->span1+my2;
+	}
+
+	for (y=my2; y>=my0; y--, span1--, span2--) {
+
+		sn1= floor(*span1);
+		sn2= floor(*span2);
+		sn1++;
+
+		if (sn2>=rectx) sn2= rectx-1;
+		if (sn1<0) sn1= 0;
+
+		if (sn2>=sn1) {
+			zverg= (double)sn1*zxd + zy0;
+			rz= rectzofs+sn1;
+			rp= rectpofs+sn1;
+			x= sn2-sn1;
+
+			while (x>=0) {
+				if (zverg < (double)*rz) {
+					*rz= zverg;
+					*rp= *col;
+				}
+				zverg+= zxd;
+				rz++;
+				rp++;
+				x--;
+			}
+		}
+
+		zy0-=zyd;
+		rectzofs-= rectx;
+		rectpofs-= rectx;
+	}
+}
+
+/* char value==255 is filled in, rest should be zero */
+/* returns alpha values, but sets alpha to 1 for zero alpha pixels that have an alpha value as neighbor */
+void antialias_tagbuf(int xsize, int ysize, char *rectmove)
+{
+	char *row1, *row2, *row3;
+	char prev, next;
+	int a, x, y, step;
+
+	/* 1: tag pixels to be candidate for AA */
+	for (y=2; y<ysize; y++) {
+		/* setup rows */
+		row1= rectmove + (y-2)*xsize;
+		row2= row1 + xsize;
+		row3= row2 + xsize;
+		for (x=2; x<xsize; x++, row1++, row2++, row3++) {
+			if (row2[1]) {
+				if (row2[0]==0 || row2[2]==0 || row1[1]==0 || row3[1]==0)
+					row2[1]= 128;
+			}
+		}
+	}
+
+	/* 2: evaluate horizontal scanlines and calculate alphas */
+	row1= rectmove;
+	for (y=0; y<ysize; y++) {
+		row1++;
+		for (x=1; x<xsize; x++, row1++) {
+			if (row1[0]==128 && row1[1]==128) {
+				/* find previous color and next color and amount of steps to blend */
+				prev= row1[-1];
+				step= 1;
+				while (x+step<xsize && row1[step]==128)
+					step++;
+
+				if (x+step!=xsize) {
+					/* now we can blend values */
+					next= row1[step];
+
+					/* note, prev value can be next value, but we do this loop to clear 128 then */
+					for (a=0; a<step; a++) {
+						int fac, mfac;
+
+						fac= ((a+1)<<8)/(step+1);
+						mfac= 255-fac;
+
+						row1[a]= (prev*mfac + next*fac)>>8;
+					}
+				}
+			}
+		}
+	}
+
+	/* 3: evaluate vertical scanlines and calculate alphas */
+	/*    use for reading a copy of the original tagged buffer */
+	for (x=0; x<xsize; x++) {
+		row1= rectmove + x+xsize;
+
+		for (y=1; y<ysize; y++, row1+=xsize) {
+			if (row1[0]==128 && row1[xsize]==128) {
+				/* find previous color and next color and amount of steps to blend */
+				prev= row1[-xsize];
+				step= 1;
+				while (y+step<ysize && row1[step*xsize]==128)
+					step++;
+
+				if (y+step!=ysize) {
+					/* now we can blend values */
+					next= row1[step*xsize];
+					/* note, prev value can be next value, but we do this loop to clear 128 then */
+					for (a=0; a<step; a++) {
+						int fac, mfac;
+
+						fac= ((a+1)<<8)/(step+1);
+						mfac= 255-fac;
+
+						row1[a*xsize]= (prev*mfac + next*fac)>>8;
+					}
+				}
+			}
+		}
+	}
+
+	/* last: pixels with 0 we fill in zbuffer, with 1 we skip for mask */
+	for (y=2; y<ysize; y++) {
+		/* setup rows */
+		row1= rectmove + (y-2)*xsize;
+		row2= row1 + xsize;
+		row3= row2 + xsize;
+		for (x=2; x<xsize; x++, row1++, row2++, row3++) {
+			if (row2[1]==0) {
+				if (row2[0]>1 || row2[2]>1 || row1[1]>1 || row3[1]>1)
+					row2[1]= 1;
+			}
+		}
+	}
+}
+
+/* in: two vectors, first vector points from origin back in time, 2nd vector points to future */
+/* we make this into 3 points, center point is (0, 0) */
+/* and offset the center point just enough to make curve go through midpoint */
+
+static void quad_bezier_2d(float *result, float *v1, float *v2, float *ipodata)
+{
+	float p1[2], p2[2], p3[2];
+
+	p3[0]= -v2[0];
+	p3[1]= -v2[1];
+
+	p1[0]= v1[0];
+	p1[1]= v1[1];
+
+	/* official formula 2*p2 - 0.5*p1 - 0.5*p3 */
+	p2[0]= -0.5f*p1[0] - 0.5f*p3[0];
+	p2[1]= -0.5f*p1[1] - 0.5f*p3[1];
+
+	result[0]= ipodata[0]*p1[0] + ipodata[1]*p2[0] + ipodata[2]*p3[0];
+	result[1]= ipodata[0]*p1[1] + ipodata[1]*p2[1] + ipodata[2]*p3[1];
+}
+
+static void set_quad_bezier_ipo(float fac, float *data)
+{
+	float mfac= (1.0f-fac);
+
+	data[0]= mfac*mfac;
+	data[1]= 2.0f*mfac*fac;
+	data[2]= fac*fac;
+}
+
+void zbuf_accumulate_vecblur(
+        NodeBlurData *nbd, int xsize, int ysize, float *newrect,
+        const float *imgrect, float *vecbufrect, const float *zbufrect)
+{
+	ZSpan zspan;
+	DrawBufPixel *rectdraw, *dr;
+	static float jit[256][2];
+	float v1[3], v2[3], v3[3], v4[3], fx, fy;
+	const float *dimg, *dz, *ro;
+	float *rectvz, *dvz, *dvec1, *dvec2, *dz1, *dz2, *rectz;
+	float *minvecbufrect= NULL, *rectweight, *rw, *rectmax, *rm;
+	float maxspeedsq= (float)nbd->maxspeed*nbd->maxspeed;
+	int y, x, step, maxspeed=nbd->maxspeed, samples= nbd->samples;
+	int tsktsk= 0;
+	static int firsttime= 1;
+	char *rectmove, *dm;
+
+	zbuf_alloc_span(&zspan, xsize, ysize, 1.0f);
+	zspan.zmulx=  ((float)xsize)/2.0f;
+	zspan.zmuly=  ((float)ysize)/2.0f;
+	zspan.zofsx= 0.0f;
+	zspan.zofsy= 0.0f;
+
+	/* the buffers */
+	rectz= (float*)MEM_mapallocN(sizeof(float)*xsize*ysize, "zbuf accum");
+	zspan.rectz= (int *)rectz;
+
+	rectmove= (char*)MEM_mapallocN(xsize*ysize, "rectmove");
+	rectdraw= (DrawBufPixel*)MEM_mapallocN(sizeof(DrawBufPixel)*xsize*ysize, "rect draw");
+	zspan.rectdraw= rectdraw;
+
+	rectweight= (float*)MEM_mapallocN(sizeof(float)*xsize*ysize, "rect weight");
+	rectmax= (float*)MEM_mapallocN(sizeof(float)*xsize*ysize, "rect max");
+
+	/* debug... check if PASS_VECTOR_MAX still is in buffers */
+	dvec1= vecbufrect;
+	for (x= 4*xsize*ysize; x>0; x--, dvec1++) {
+		if (dvec1[0]==PASS_VECTOR_MAX) {
+			dvec1[0]= 0.0f;
+			tsktsk= 1;
+		}
+	}
+	if (tsktsk) printf("Found uninitialized speed in vector buffer... fixed.\n");
+
+	/* min speed? then copy speedbuffer to recalculate speed vectors */
+	if (nbd->minspeed) {
+		float minspeed= (float)nbd->minspeed;
+		float minspeedsq= minspeed*minspeed;
+
+		minvecbufrect= (float*)MEM_mapallocN(4*sizeof(float)*xsize*ysize, "minspeed buf");
+
+		dvec1= vecbufrect;
+		dvec2= minvecbufrect;
+		for (x= 2*xsize*ysize; x>0; x--, dvec1+=2, dvec2+=2) {
+			if (dvec1[0]==0.0f && dvec1[1]==0.0f) {
+				dvec2[0]= dvec1[0];
+				dvec2[1]= dvec1[1];
+			}
+			else {
+				float speedsq= dvec1[0]*dvec1[0] + dvec1[1]*dvec1[1];
+				if (speedsq <= minspeedsq) {
+					dvec2[0]= 0.0f;
+					dvec2[1]= 0.0f;
+				}
+				else {
+					speedsq = 1.0f - minspeed / sqrtf(speedsq);
+					dvec2[0]= speedsq*dvec1[0];
+					dvec2[1]= speedsq*dvec1[1];
+				}
+			}
+		}
+		SWAP(float *, minvecbufrect, vecbufrect);
+	}
+
+	/* make vertex buffer with averaged speed and zvalues */
+	rectvz= (float*)MEM_mapallocN(4*sizeof(float)*(xsize+1)*(ysize+1), "vertices");
+	dvz= rectvz;
+	for (y=0; y<=ysize; y++) {
+
+		if (y==0)
+			dvec1= vecbufrect + 4*y*xsize;
+		else
+			dvec1= vecbufrect + 4*(y-1)*xsize;
+
+		if (y==ysize)
+			dvec2= vecbufrect + 4*(y-1)*xsize;
+		else
+			dvec2= vecbufrect + 4*y*xsize;
+
+		for (x=0; x<=xsize; x++) {
+
+			/* two vectors, so a step loop */
+			for (step=0; step<2; step++, dvec1+=2, dvec2+=2, dvz+=2) {
+				/* average on minimal speed */
+				int div= 0;
+
+				if (x!=0) {
+					if (dvec1[-4]!=0.0f || dvec1[-3]!=0.0f) {
+						dvz[0]= dvec1[-4];
+						dvz[1]= dvec1[-3];
+						div++;
+					}
+					if (dvec2[-4]!=0.0f || dvec2[-3]!=0.0f) {
+						if (div==0) {
+							dvz[0]= dvec2[-4];
+							dvz[1]= dvec2[-3];
+							div++;
+						}
+						else if ( (ABS(dvec2[-4]) + ABS(dvec2[-3]))< (ABS(dvz[0]) + ABS(dvz[1])) ) {
+							dvz[0]= dvec2[-4];
+							dvz[1]= dvec2[-3];
+						}
+					}
+				}
+
+				if (x!=xsize) {
+					if (dvec1[0]!=0.0f || dvec1[1]!=0.0f) {
+						if (div==0) {
+							dvz[0]= dvec1[0];
+							dvz[1]= dvec1[1];
+							div++;
+						}
+						else if ( (ABS(dvec1[0]) + ABS(dvec1[1]))< (ABS(dvz[0]) + ABS(dvz[1])) ) {
+							dvz[0]= dvec1[0];
+							dvz[1]= dvec1[1];
+						}
+					}
+					if (dvec2[0]!=0.0f || dvec2[1]!=0.0f) {
+						if (div==0) {
+							dvz[0]= dvec2[0];
+							dvz[1]= dvec2[1];
+						}
+						else if ( (ABS(dvec2[0]) + ABS(dvec2[1]))< (ABS(dvz[0]) + ABS(dvz[1])) ) {
+							dvz[0]= dvec2[0];
+							dvz[1]= dvec2[1];
+						}
+					}
+				}
+				if (maxspeed) {
+					float speedsq= dvz[0]*dvz[0] + dvz[1]*dvz[1];
+					if (speedsq > maxspeedsq) {
+						speedsq = (float)maxspeed / sqrtf(speedsq);
+						dvz[0]*= speedsq;
+						dvz[1]*= speedsq;
+					}
+				}
+			}
+		}
+	}
+
+	/* set border speeds to keep border speeds on border */
+	dz1= rectvz;
+	dz2= rectvz+4*(ysize)*(xsize+1);
+	for (x=0; x<=xsize; x++, dz1+=4, dz2+=4) {
+		dz1[1]= 0.0f;
+		dz2[1]= 0.0f;
+		dz1[3]= 0.0f;
+		dz2[3]= 0.0f;
+	}
+	dz1= rectvz;
+	dz2= rectvz+4*(xsize);
+	for (y=0; y<=ysize; y++, dz1+=4*(xsize+1), dz2+=4*(xsize+1)) {
+		dz1[0]= 0.0f;
+		dz2[0]= 0.0f;
+		dz1[2]= 0.0f;
+		dz2[2]= 0.0f;
+	}
+
+	/* tag moving pixels, only these faces we draw */
+	dm= rectmove;
+	dvec1= vecbufrect;
+	for (x=xsize*ysize; x>0; x--, dm++, dvec1+=4) {
+		if ((dvec1[0]!=0.0f || dvec1[1]!=0.0f || dvec1[2]!=0.0f || dvec1[3]!=0.0f))
+			*dm= 255;
+	}
+
+	antialias_tagbuf(xsize, ysize, rectmove);
+
+	/* has to become static, the init-jit calls a random-seed, screwing up texture noise node */
+	if (firsttime) {
+		firsttime= 0;
+		BLI_jitter_init(jit, 256);
+	}
+
+	memset(newrect, 0, sizeof(float)*xsize*ysize*4);
+
+	/* accumulate */
+	samples/= 2;
+	for (step= 1; step<=samples; step++) {
+		float speedfac= 0.5f*nbd->fac*(float)step/(float)(samples+1);
+		int side;
+
+		for (side=0; side<2; side++) {
+			float blendfac, ipodata[4];
+
+			/* clear zbuf, if we draw future we fill in not moving pixels */
+			if (0)
+				for (x= xsize*ysize-1; x>=0; x--) rectz[x]= 10e16;
+			else
+				for (x= xsize*ysize-1; x>=0; x--) {
+					if (rectmove[x]==0)
+						rectz[x]= zbufrect[x];
+					else
+						rectz[x]= 10e16;
+				}
+
+			/* clear drawing buffer */
+			for (x= xsize*ysize-1; x>=0; x--) rectdraw[x].colpoin= NULL;
+
+			dimg= imgrect;
+			dm= rectmove;
+			dz= zbufrect;
+			dz1= rectvz;
+			dz2= rectvz + 4*(xsize + 1);
+
+			if (side) {
+				if (nbd->curved==0) {
+					dz1+= 2;
+					dz2+= 2;
+				}
+				speedfac= -speedfac;
+			}
+
+			set_quad_bezier_ipo(0.5f + 0.5f*speedfac, ipodata);
+
+			for (fy= -0.5f+jit[step & 255][0], y=0; y<ysize; y++, fy+=1.0f) {
+				for (fx= -0.5f+jit[step & 255][1], x=0; x<xsize; x++, fx+=1.0f, dimg+=4, dz1+=4, dz2+=4, dm++, dz++) {
+					if (*dm>1) {
+						float jfx = fx + 0.5f;
+						float jfy = fy + 0.5f;
+						DrawBufPixel col;
+
+						/* make vertices */
+						if (nbd->curved) {	/* curved */
+							quad_bezier_2d(v1, dz1, dz1+2, ipodata);
+							v1[0]+= jfx; v1[1]+= jfy; v1[2]= *dz;
+
+							quad_bezier_2d(v2, dz1+4, dz1+4+2, ipodata);
+							v2[0]+= jfx+1.0f; v2[1]+= jfy; v2[2]= *dz;
+
+							quad_bezier_2d(v3, dz2+4, dz2+4+2, ipodata);
+							v3[0]+= jfx+1.0f; v3[1]+= jfy+1.0f; v3[2]= *dz;
+
+							quad_bezier_2d(v4, dz2, dz2+2, ipodata);
+							v4[0]+= jfx; v4[1]+= jfy+1.0f; v4[2]= *dz;
+						}
+						else {
+							v1[0]= speedfac*dz1[0]+jfx;      v1[1]= speedfac*dz1[1]+jfy;      v1[2]= *dz;
+							v2[0]= speedfac*dz1[4]+jfx+1.0f; v2[1]= speedfac*dz1[5]+jfy;      v2[2]= *dz;
+							v3[0]= speedfac*dz2[4]+jfx+1.0f; v3[1]= speedfac*dz2[5]+jfy+1.0f; v3[2]= *dz;
+							v4[0]= speedfac*dz2[0]+jfx;      v4[1]= speedfac*dz2[1]+jfy+1.0f; v4[2]= *dz;
+						}
+						if (*dm==255) col.alpha= 1.0f;
+						else if (*dm<2) col.alpha= 0.0f;
+						else col.alpha= ((float)*dm)/255.0f;
+						col.colpoin= dimg;
+
+						zbuf_fill_in_rgba(&zspan, &col, v1, v2, v3, v4);
+					}
+				}
+				dz1+=4;
+				dz2+=4;
+			}
+
+			/* blend with a falloff. this fixes the ugly effect you get with
+			 * a fast moving object. then it looks like a solid object overlayed
+			 * over a very transparent moving version of itself. in reality, the
+			 * whole object should become transparent if it is moving fast, be
+			 * we don't know what is behind it so we don't do that. this hack
+			 * overestimates the contribution of foreground pixels but looks a
+			 * bit better without a sudden cutoff. */
+			blendfac= ((samples - step)/(float)samples);
+			/* smoothstep to make it look a bit nicer as well */
+			blendfac= 3.0f*pow(blendfac, 2.0f) - 2.0f*pow(blendfac, 3.0f);
+
+			/* accum */
+			rw= rectweight;
+			rm= rectmax;
+			for (dr= rectdraw, dz2=newrect, x= xsize*ysize-1; x>=0; x--, dr++, dz2+=4, rw++, rm++) {
+				if (dr->colpoin) {
+					float bfac= dr->alpha*blendfac;
+
+					dz2[0] += bfac*dr->colpoin[0];
+					dz2[1] += bfac*dr->colpoin[1];
+					dz2[2] += bfac*dr->colpoin[2];
+					dz2[3] += bfac*dr->colpoin[3];
+
+					*rw += bfac;
+					*rm= MAX2(*rm, bfac);
+				}
+			}
+		}
+	}
+
+	/* blend between original images and accumulated image */
+	rw= rectweight;
+	rm= rectmax;
+	ro= imgrect;
+	dm= rectmove;
+	for (dz2=newrect, x= xsize*ysize-1; x>=0; x--, dz2+=4, ro+=4, rw++, rm++, dm++) {
+		float mfac = *rm;
+		float fac = (*rw == 0.0f)? 0.0f: mfac/(*rw);
+		float nfac = 1.0f - mfac;
+
+		dz2[0]= fac*dz2[0] + nfac*ro[0];
+		dz2[1]= fac*dz2[1] + nfac*ro[1];
+		dz2[2]= fac*dz2[2] + nfac*ro[2];
+		dz2[3]= fac*dz2[3] + nfac*ro[3];
+	}
+
+	MEM_freeN(rectz);
+	MEM_freeN(rectmove);
+	MEM_freeN(rectdraw);
+	MEM_freeN(rectvz);
+	MEM_freeN(rectweight);
+	MEM_freeN(rectmax);
+	if (minvecbufrect) MEM_freeN(vecbufrect);  /* rects were swapped! */
+	zbuf_free_span(&zspan);
+}