364 lines
6.8 KiB
C
364 lines
6.8 KiB
C
/*
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* We draw a triangle with various interpolations
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*/
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{
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ZBufferPoint *t,*pr1,*pr2,*l1,*l2;
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float fdx1, fdx2, fdy1, fdy2, fz, d1, d2;
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unsigned short *pz1;
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PIXEL *pp1;
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int part,update_left,update_right;
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int nb_lines,dx1,dy1,tmp,dx2,dy2;
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int error,derror;
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int x1,dxdy_min,dxdy_max;
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/* warning: x2 is multiplied by 2^16 */
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int x2,dx2dy2;
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#ifdef INTERP_Z
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int z1,dzdx,dzdy,dzdl_min,dzdl_max;
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#endif
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#ifdef INTERP_RGB
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int r1,drdx,drdy,drdl_min,drdl_max;
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int g1,dgdx,dgdy,dgdl_min,dgdl_max;
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int b1,dbdx,dbdy,dbdl_min,dbdl_max;
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#endif
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#ifdef INTERP_ST
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int s1,dsdx,dsdy,dsdl_min,dsdl_max;
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int t1,dtdx,dtdy,dtdl_min,dtdl_max;
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#endif
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#ifdef INTERP_STZ
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float sz1,dszdx,dszdy,dszdl_min,dszdl_max;
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float tz1,dtzdx,dtzdy,dtzdl_min,dtzdl_max;
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#endif
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/* we sort the vertex with increasing y */
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if (p1->y < p0->y) {
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t = p0;
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p0 = p1;
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p1 = t;
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}
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if (p2->y < p0->y) {
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t = p2;
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p2 = p1;
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p1 = p0;
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p0 = t;
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} else if (p2->y < p1->y) {
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t = p1;
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p1 = p2;
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p2 = t;
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}
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/* we compute dXdx and dXdy for all interpolated values */
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fdx1 = p1->x - p0->x;
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fdy1 = p1->y - p0->y;
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fdx2 = p2->x - p0->x;
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fdy2 = p2->y - p0->y;
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fz = fdx1 * fdy2 - fdx2 * fdy1;
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if (fz == 0)
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return;
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fz = 1.0 / fz;
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fdx1 *= fz;
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fdy1 *= fz;
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fdx2 *= fz;
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fdy2 *= fz;
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#ifdef INTERP_Z
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d1 = p1->z - p0->z;
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d2 = p2->z - p0->z;
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dzdx = (int) (fdy2 * d1 - fdy1 * d2);
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dzdy = (int) (fdx1 * d2 - fdx2 * d1);
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#endif
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#ifdef INTERP_RGB
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d1 = p1->r - p0->r;
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d2 = p2->r - p0->r;
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drdx = (int) (fdy2 * d1 - fdy1 * d2);
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drdy = (int) (fdx1 * d2 - fdx2 * d1);
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d1 = p1->g - p0->g;
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d2 = p2->g - p0->g;
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dgdx = (int) (fdy2 * d1 - fdy1 * d2);
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dgdy = (int) (fdx1 * d2 - fdx2 * d1);
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d1 = p1->b - p0->b;
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d2 = p2->b - p0->b;
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dbdx = (int) (fdy2 * d1 - fdy1 * d2);
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dbdy = (int) (fdx1 * d2 - fdx2 * d1);
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#endif
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#ifdef INTERP_ST
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d1 = p1->s - p0->s;
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d2 = p2->s - p0->s;
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dsdx = (int) (fdy2 * d1 - fdy1 * d2);
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dsdy = (int) (fdx1 * d2 - fdx2 * d1);
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d1 = p1->t - p0->t;
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d2 = p2->t - p0->t;
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dtdx = (int) (fdy2 * d1 - fdy1 * d2);
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dtdy = (int) (fdx1 * d2 - fdx2 * d1);
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#endif
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#ifdef INTERP_STZ
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{
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float zz;
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zz=(float) p0->z;
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p0->sz= (float) p0->s * zz;
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p0->tz= (float) p0->t * zz;
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zz=(float) p1->z;
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p1->sz= (float) p1->s * zz;
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p1->tz= (float) p1->t * zz;
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zz=(float) p2->z;
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p2->sz= (float) p2->s * zz;
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p2->tz= (float) p2->t * zz;
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d1 = p1->sz - p0->sz;
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d2 = p2->sz - p0->sz;
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dszdx = (fdy2 * d1 - fdy1 * d2);
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dszdy = (fdx1 * d2 - fdx2 * d1);
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d1 = p1->tz - p0->tz;
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d2 = p2->tz - p0->tz;
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dtzdx = (fdy2 * d1 - fdy1 * d2);
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dtzdy = (fdx1 * d2 - fdx2 * d1);
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}
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#endif
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/* screen coordinates */
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pp1 = (PIXEL *) ((char *) zb->pbuf + zb->linesize * p0->y);
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pz1 = zb->zbuf + p0->y * zb->xsize;
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DRAW_INIT();
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for(part=0;part<2;part++) {
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if (part == 0) {
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if (fz > 0) {
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update_left=1;
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update_right=1;
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l1=p0;
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l2=p2;
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pr1=p0;
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pr2=p1;
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} else {
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update_left=1;
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update_right=1;
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l1=p0;
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l2=p1;
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pr1=p0;
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pr2=p2;
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}
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nb_lines = p1->y - p0->y;
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} else {
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/* second part */
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if (fz > 0) {
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update_left=0;
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update_right=1;
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pr1=p1;
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pr2=p2;
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} else {
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update_left=1;
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update_right=0;
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l1=p1;
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l2=p2;
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}
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nb_lines = p2->y - p1->y + 1;
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}
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/* compute the values for the left edge */
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if (update_left) {
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dy1 = l2->y - l1->y;
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dx1 = l2->x - l1->x;
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if (dy1 > 0)
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tmp = (dx1 << 16) / dy1;
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else
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tmp = 0;
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x1 = l1->x;
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error = 0;
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derror = tmp & 0x0000ffff;
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dxdy_min = tmp >> 16;
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dxdy_max = dxdy_min + 1;
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#ifdef INTERP_Z
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z1=l1->z;
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dzdl_min=(dzdy + dzdx * dxdy_min);
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dzdl_max=dzdl_min + dzdx;
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#endif
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#ifdef INTERP_RGB
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r1=l1->r;
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drdl_min=(drdy + drdx * dxdy_min);
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drdl_max=drdl_min + drdx;
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g1=l1->g;
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dgdl_min=(dgdy + dgdx * dxdy_min);
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dgdl_max=dgdl_min + dgdx;
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b1=l1->b;
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dbdl_min=(dbdy + dbdx * dxdy_min);
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dbdl_max=dbdl_min + dbdx;
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#endif
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#ifdef INTERP_ST
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s1=l1->s;
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dsdl_min=(dsdy + dsdx * dxdy_min);
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dsdl_max=dsdl_min + dsdx;
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t1=l1->t;
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dtdl_min=(dtdy + dtdx * dxdy_min);
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dtdl_max=dtdl_min + dtdx;
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#endif
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#ifdef INTERP_STZ
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sz1=l1->sz;
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dszdl_min=(dszdy + dszdx * dxdy_min);
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dszdl_max=dszdl_min + dszdx;
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tz1=l1->tz;
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dtzdl_min=(dtzdy + dtzdx * dxdy_min);
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dtzdl_max=dtzdl_min + dtzdx;
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#endif
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}
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/* compute values for the right edge */
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if (update_right) {
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dx2 = (pr2->x - pr1->x);
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dy2 = (pr2->y - pr1->y);
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if (dy2>0)
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dx2dy2 = ( dx2 << 16) / dy2;
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else
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dx2dy2 = 0;
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x2 = pr1->x << 16;
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}
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/* we draw all the scan line of the part */
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while (nb_lines>0) {
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nb_lines--;
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#ifndef DRAW_LINE
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/* generic draw line */
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{
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register PIXEL *pp;
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register int n;
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#ifdef INTERP_Z
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register unsigned short *pz;
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register unsigned int z,zz;
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#endif
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#ifdef INTERP_RGB
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register unsigned int or1,og1,ob1;
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#endif
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#ifdef INTERP_ST
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register unsigned int s,t;
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#endif
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#ifdef INTERP_STZ
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float sz,tz;
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#endif
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n=(x2 >> 16) - x1;
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pp=(PIXEL *)((char *)pp1 + x1 * PSZB);
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#ifdef INTERP_Z
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pz=pz1+x1;
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z=z1;
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#endif
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#ifdef INTERP_RGB
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or1 = r1;
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og1 = g1;
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ob1 = b1;
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#endif
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#ifdef INTERP_ST
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s=s1;
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t=t1;
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#endif
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#ifdef INTERP_STZ
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sz=sz1;
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tz=tz1;
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#endif
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while (n>=3) {
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PUT_PIXEL(0);
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PUT_PIXEL(1);
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PUT_PIXEL(2);
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PUT_PIXEL(3);
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#ifdef INTERP_Z
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pz+=4;
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#endif
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pp=(PIXEL *)((char *)pp + 4 * PSZB);
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n-=4;
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}
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while (n>=0) {
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PUT_PIXEL(0);
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#ifdef INTERP_Z
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pz+=1;
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#endif
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pp=(PIXEL *)((char *)pp + PSZB);
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n-=1;
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}
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}
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#else
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DRAW_LINE();
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#endif
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/* left edge */
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error+=derror;
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if (error > 0) {
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error-=0x10000;
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x1+=dxdy_max;
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#ifdef INTERP_Z
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z1+=dzdl_max;
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#endif
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#ifdef INTERP_RGB
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r1+=drdl_max;
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g1+=dgdl_max;
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b1+=dbdl_max;
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#endif
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#ifdef INTERP_ST
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s1+=dsdl_max;
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t1+=dtdl_max;
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#endif
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#ifdef INTERP_STZ
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sz1+=dszdl_max;
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tz1+=dtzdl_max;
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#endif
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} else {
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x1+=dxdy_min;
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#ifdef INTERP_Z
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z1+=dzdl_min;
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#endif
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#ifdef INTERP_RGB
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r1+=drdl_min;
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g1+=dgdl_min;
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b1+=dbdl_min;
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#endif
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#ifdef INTERP_ST
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s1+=dsdl_min;
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t1+=dtdl_min;
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#endif
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#ifdef INTERP_STZ
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sz1+=dszdl_min;
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tz1+=dtzdl_min;
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#endif
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}
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/* right edge */
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x2+=dx2dy2;
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/* screen coordinates */
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pp1=(PIXEL *)((char *)pp1 + zb->linesize);
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pz1+=zb->xsize;
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}
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}
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}
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#undef INTERP_Z
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#undef INTERP_RGB
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#undef INTERP_ST
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#undef INTERP_STZ
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#undef DRAW_INIT
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#undef DRAW_LINE
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#undef PUT_PIXEL
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