291 lines
6.0 KiB
C
291 lines
6.0 KiB
C
extern int finite(double);
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/* undef'ing this makes things look a bit nicer, but slower */
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#define DBL_PIXELS
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void
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NAME(fzort_ctx *ctx, struct pvertex *v1,
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struct pvertex *v2, struct pvertex *v3)
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{
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long x_left, x_right, dxdy_left, dxdy_right;
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struct pvertex *v_min, *v_mid, *v_max;
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struct edge e_maj, e_top, e_bot, *e_left, *e_right;
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float area, inv_area, bf = 1.f;
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long dudy, dudy_left, u_left;
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long dvdy, dvdy_left, v_left;
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int sub_tri, left_to_right, y, lines;
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int xa, xb, adjx;
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PIXEL_TYPE *scanline_ptr;
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PIXEL_TYPE *texture_ptr;
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register int l;
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register long u, v, dudx, dvdx;
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#if (defined DBL_PIXELS) && !(defined MONOCHROME)
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register PIXEL_TYPE t;
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register long dudx2, dvdx2, dudx4, dvdx4;
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#endif
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register PIXEL_TYPE *pixel_ptr;
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#ifdef MONOCHROME
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register unsigned int mask, bits;
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register unsigned int *dither_ptr;
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#endif
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texture_ptr = (PIXEL_TYPE *)ctx->texture;
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if (v1->y_scr <= v2->y_scr) {
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if (v2->y_scr <= v3->y_scr) {
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v_min = v1; v_mid = v2; v_max = v3;
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} else if (v3->y_scr <= v1->y_scr) {
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v_min = v3; v_mid = v1; v_max = v2;
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} else {
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v_min = v1; v_mid = v3; v_max = v2;
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bf = -bf;
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}
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} else {
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if (v1->y_scr <= v3->y_scr) {
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v_min = v2; v_mid = v1; v_max = v3;
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bf = -bf;
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} else if (v3->y_scr <= v2->y_scr) {
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v_min = v3; v_mid = v2; v_max = v1;
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bf = -bf;
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} else {
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v_min = v2; v_mid = v3; v_max = v1;
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}
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}
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area = (v_max->x_scr - v_min->x_scr)*(v_mid->y_scr - v_min->y_scr) -
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(v_mid->x_scr - v_min->x_scr)*(v_max->y_scr - v_min->y_scr);
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if (!finite(area) || area == 0.)
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return;
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if (area*bf < 0.)
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return;
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init_edge(ctx, &e_maj, v_min, v_max);
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if (e_maj.lines == 0)
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return;
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init_edge(ctx, &e_top, v_mid, v_max);
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init_edge(ctx, &e_bot, v_min, v_mid);
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left_to_right = area < 0.; /* inter edge is to the left */
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inv_area = 1./area;
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dudx = (long) (inv_area*(e_maj.du*e_bot.dy - e_maj.dy*e_bot.du));
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dudy = (long) (inv_area*(e_maj.dx*e_bot.du - e_maj.du*e_bot.dx));
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dvdx = (long) (inv_area*(e_maj.dv*e_bot.dy - e_maj.dy*e_bot.dv));
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dvdy = (long) (inv_area*(e_maj.dx*e_bot.dv - e_maj.dv*e_bot.dx));
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#if (defined DBL_PIXELS) && !(defined MONOCHROME)
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dudx2 = dudx*2;
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dvdx2 = dvdx*2;
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dudx4 = dudx2*2;
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dvdx4 = dvdx2*2;
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#endif
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x_left = x_right = dxdy_left = dxdy_right = 0; /* shut up compiler */
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u_left = dudy_left = v_left = dvdy_left = 0;
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for (sub_tri = 0; sub_tri <= 1; sub_tri++) {
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if (sub_tri == 0) {
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if (left_to_right) {
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e_left = &e_maj;
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e_right = &e_bot;
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lines = e_right->lines;
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} else {
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e_left = &e_bot;
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e_right = &e_maj;
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lines = e_left->lines;
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}
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x_left = e_left->sx;
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dxdy_left = e_left->dxdy;
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x_right = e_right->sx;
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dxdy_right = e_right->dxdy;
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dudy_left = fp_mul(dxdy_left, dudx) + dudy;
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u_left = v_min->u_txt;
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dvdy_left = fp_mul(dxdy_left, dvdx) + dvdy;
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v_left = v_min->v_txt;
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if (e_left->adjy) {
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u_left += e_left->adjy*dudy_left;
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v_left += e_left->adjy*dvdy_left;
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}
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y = e_left->sy;
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} else {
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if (left_to_right) {
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e_right = &e_top;
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lines = e_right->lines;
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y = e_right->sy;
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x_right = e_right->sx;
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dxdy_right = e_right->dxdy;
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} else {
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e_left = &e_top;
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lines = e_left->lines;
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y = e_left->sy;
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x_left = e_left->sx;
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dxdy_left = e_left->dxdy;
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dudy_left = fp_mul(dxdy_left, dudx) + dudy;
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u_left = v_mid->u_txt;
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dvdy_left = fp_mul(dxdy_left, dvdx) + dvdy;
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v_left = v_mid->v_txt;
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if (e_left->adjy) {
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u_left += e_left->adjy*dudy_left;
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v_left += e_left->adjy*dvdy_left;
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}
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}
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}
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if (lines > 0) {
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scanline_ptr = (PIXEL_TYPE *)((unsigned char *)ctx->raster.bits +
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y*ctx->raster.pitch);
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while (lines--) {
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xa = FP_ICEIL(x_left);
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xb = FP_IFLOOR(x_right);
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if (xa < ctx->clip.x_min) {
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adjx = ctx->clip.x_min - xa;
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xa = ctx->clip.x_min;
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} else {
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adjx = 0;
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}
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if (xb > ctx->clip.x_max) {
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xb = ctx->clip.x_max;
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}
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if (xb >= ctx->clip.x_min && xa <= xb) {
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u = u_left;
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v = v_left;
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if (adjx) {
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u += dudx*adjx;
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v += dvdx*adjx;
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}
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#ifdef MONOCHROME
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pixel_ptr = scanline_ptr + (xa>>3);
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dither_ptr = &dither6[y&7][xa&7];
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#ifdef LSB_TO_MSB
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mask = 1 << (xa&7);
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#else
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mask = 1 << (7 - (xa&7));
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#endif
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#else
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pixel_ptr = scanline_ptr + xa;
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#endif
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l = 1 + xb - xa;
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#define TEXTURE_PIXEL texture_ptr[(FP_TO_INT(v)&(TEXTURE_SIZE - 1)) + \
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(FP_TO_INT(u)&(TEXTURE_SIZE - 1))*TEXTURE_SIZE]
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#ifdef MONOCHROME
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bits = *pixel_ptr;
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while (l--) {
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if ((TEXTURE_PIXEL>>2) > *dither_ptr++)
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bits |= mask;
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else
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bits &= ~mask;
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#ifdef LSB_TO_MSB
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if ((mask <<= 1) == (1<<8)) {
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#else
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if (!(mask >>= 1)) {
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#endif
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*pixel_ptr++ = bits;
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bits = *pixel_ptr;
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dither_ptr -= 8;
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#ifdef LSB_TO_MSB
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mask = 1;
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#else
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mask = 1<<7;
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#endif
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}
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u += dudx; v += dvdx;
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}
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*pixel_ptr = bits;
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#else
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if (l & 1) {
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*pixel_ptr++ = TEXTURE_PIXEL;
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u += dudx; v += dvdx;
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}
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l >>= 1;
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if (l & 1) {
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#ifdef DBL_PIXELS
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t = TEXTURE_PIXEL;
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pixel_ptr[0] = t; pixel_ptr[1] = t;
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pixel_ptr += 2;
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u += dudx2; v += dvdx2;
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#else
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*pixel_ptr++ = TEXTURE_PIXEL;
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u += dudx; v += dvdx;
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*pixel_ptr++ = TEXTURE_PIXEL;
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u += dudx; v += dvdx;
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#endif
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}
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l >>= 1;
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while (l--) {
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#ifdef DBL_PIXELS
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t = TEXTURE_PIXEL;
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pixel_ptr[0] = t; pixel_ptr[1] = t;
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pixel_ptr[2] = t; pixel_ptr[3] = t;
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pixel_ptr += 4;
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u += dudx4; v += dvdx4;
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#else
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*pixel_ptr++ = TEXTURE_PIXEL;
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u += dudx; v += dvdx;
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*pixel_ptr++ = TEXTURE_PIXEL;
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u += dudx; v += dvdx;
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*pixel_ptr++ = TEXTURE_PIXEL;
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u += dudx; v += dvdx;
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*pixel_ptr++ = TEXTURE_PIXEL;
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u += dudx; v += dvdx;
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#endif
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}
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#endif /* MONOCHROME */
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#undef TEXTURE_PIXEL
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}
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scanline_ptr += ctx->raster.pitch/sizeof(*scanline_ptr);
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x_left += dxdy_left;
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x_right += dxdy_right;
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u_left += dudy_left;
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v_left += dvdy_left;
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y++;
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}
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}
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}
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}
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#undef LSB_TO_MSB
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#undef MONOCHROME
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#undef FILL_SCANLINE
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#undef PIXEL_TYPE
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#undef NAME
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