ref: 81829a02f3745b7914ed8f6f95632a3757c71073
dir: /qw/d_sprite.c/
// d_sprite.c: software top-level rasterization driver module for drawing sprites #include <u.h> #include <libc.h> #include <stdio.h> #include "quakedef.h" static int sprite_height; static int minindex, maxindex; static sspan_t *sprite_spans; /* ===================== D_SpriteDrawSpans ===================== */ void D_SpriteDrawSpans (sspan_t *pspan) { int count, spancount, izistep; int izi; byte *pbase, *pdest; fixed16_t s, t, snext, tnext, sstep, tstep; float sdivz, tdivz, zi, z, du, dv, spancountminus1; float sdivz8stepu, tdivz8stepu, zi8stepu; byte btemp; short *pz; sstep = 0; // keep compiler happy tstep = 0; // ditto pbase = cacheblock; sdivz8stepu = d_sdivzstepu * 8; tdivz8stepu = d_tdivzstepu * 8; zi8stepu = d_zistepu * 8; // we count on FP exceptions being turned off to avoid range problems izistep = (int)(d_zistepu * 0x8000 * 0x10000); do { pdest = (byte *)d_viewbuffer + (screenwidth * pspan->v) + pspan->u; pz = d_pzbuffer + (d_zwidth * pspan->v) + pspan->u; count = pspan->count; if (count <= 0) goto NextSpan; // calculate the initial s/z, t/z, 1/z, s, and t and clamp du = (float)pspan->u; dv = (float)pspan->v; sdivz = d_sdivzorigin + dv*d_sdivzstepv + du*d_sdivzstepu; tdivz = d_tdivzorigin + dv*d_tdivzstepv + du*d_tdivzstepu; zi = d_ziorigin + dv*d_zistepv + du*d_zistepu; z = (float)0x10000 / zi; // prescale to 16.16 fixed-point // we count on FP exceptions being turned off to avoid range problems izi = (int)(zi * 0x8000 * 0x10000); s = (int)(sdivz * z) + sadjust; if (s > bbextents) s = bbextents; else if (s < 0) s = 0; t = (int)(tdivz * z) + tadjust; if (t > bbextentt) t = bbextentt; else if (t < 0) t = 0; do { // calculate s and t at the far end of the span if (count >= 8) spancount = 8; else spancount = count; count -= spancount; if (count) { // calculate s/z, t/z, zi->fixed s and t at far end of span, // calculate s and t steps across span by shifting sdivz += sdivz8stepu; tdivz += tdivz8stepu; zi += zi8stepu; z = (float)0x10000 / zi; // prescale to 16.16 fixed-point snext = (int)(sdivz * z) + sadjust; if (snext > bbextents) snext = bbextents; else if (snext < 8) snext = 8; // prevent round-off error on <0 steps from // from causing overstepping & running off the // edge of the texture tnext = (int)(tdivz * z) + tadjust; if (tnext > bbextentt) tnext = bbextentt; else if (tnext < 8) tnext = 8; // guard against round-off error on <0 steps sstep = (snext - s) >> 3; tstep = (tnext - t) >> 3; } else { // calculate s/z, t/z, zi->fixed s and t at last pixel in span (so // can't step off polygon), clamp, calculate s and t steps across // span by division, biasing steps low so we don't run off the // texture spancountminus1 = (float)(spancount - 1); sdivz += d_sdivzstepu * spancountminus1; tdivz += d_tdivzstepu * spancountminus1; zi += d_zistepu * spancountminus1; z = (float)0x10000 / zi; // prescale to 16.16 fixed-point snext = (int)(sdivz * z) + sadjust; if (snext > bbextents) snext = bbextents; else if (snext < 8) snext = 8; // prevent round-off error on <0 steps from // from causing overstepping & running off the // edge of the texture tnext = (int)(tdivz * z) + tadjust; if (tnext > bbextentt) tnext = bbextentt; else if (tnext < 8) tnext = 8; // guard against round-off error on <0 steps if (spancount > 1) { sstep = (snext - s) / (spancount - 1); tstep = (tnext - t) / (spancount - 1); } } do { btemp = *(pbase + (s >> 16) + (t >> 16) * cachewidth); if (btemp != 255) { if (*pz <= (izi >> 16)) { *pz = izi >> 16; *pdest = btemp; } } izi += izistep; pdest++; pz++; s += sstep; t += tstep; } while (--spancount > 0); s = snext; t = tnext; } while (count > 0); NextSpan: pspan++; } while (pspan->count != DS_SPAN_LIST_END); } /* ===================== D_SpriteScanLeftEdge ===================== */ void D_SpriteScanLeftEdge (void) { int i, v, itop, ibottom, lmaxindex; emitpoint_t *pvert, *pnext; sspan_t *pspan; float du, dv, vtop, vbottom, slope; fixed16_t u, u_step; pspan = sprite_spans; i = minindex; if (i == 0) i = r_spritedesc.nump; lmaxindex = maxindex; if (lmaxindex == 0) lmaxindex = r_spritedesc.nump; vtop = ceil (r_spritedesc.pverts[i].v); do { pvert = &r_spritedesc.pverts[i]; pnext = pvert - 1; vbottom = ceil (pnext->v); if (vtop < vbottom) { du = pnext->u - pvert->u; dv = pnext->v - pvert->v; slope = du / dv; u_step = (int)(slope * 0x10000); // adjust u to ceil the integer portion u = (int)((pvert->u + (slope * (vtop - pvert->v))) * 0x10000) + (0x10000 - 1); itop = (int)vtop; ibottom = (int)vbottom; for (v=itop ; v<ibottom ; v++) { pspan->u = u >> 16; pspan->v = v; u += u_step; pspan++; } } vtop = vbottom; i--; if (i == 0) i = r_spritedesc.nump; } while (i != lmaxindex); } /* ===================== D_SpriteScanRightEdge ===================== */ void D_SpriteScanRightEdge (void) { int i, v, itop, ibottom; emitpoint_t *pvert, *pnext; sspan_t *pspan; float du, dv, vtop, vbottom, slope, uvert, unext, vvert, vnext; fixed16_t u, u_step; pspan = sprite_spans; i = minindex; vvert = r_spritedesc.pverts[i].v; if (vvert < r_refdef.fvrecty_adj) vvert = r_refdef.fvrecty_adj; if (vvert > r_refdef.fvrectbottom_adj) vvert = r_refdef.fvrectbottom_adj; vtop = ceil (vvert); do { pvert = &r_spritedesc.pverts[i]; pnext = pvert + 1; vnext = pnext->v; if (vnext < r_refdef.fvrecty_adj) vnext = r_refdef.fvrecty_adj; if (vnext > r_refdef.fvrectbottom_adj) vnext = r_refdef.fvrectbottom_adj; vbottom = ceil (vnext); if (vtop < vbottom) { uvert = pvert->u; if (uvert < r_refdef.fvrectx_adj) uvert = r_refdef.fvrectx_adj; if (uvert > r_refdef.fvrectright_adj) uvert = r_refdef.fvrectright_adj; unext = pnext->u; if (unext < r_refdef.fvrectx_adj) unext = r_refdef.fvrectx_adj; if (unext > r_refdef.fvrectright_adj) unext = r_refdef.fvrectright_adj; du = unext - uvert; dv = vnext - vvert; slope = du / dv; u_step = (int)(slope * 0x10000); // adjust u to ceil the integer portion u = (int)((uvert + (slope * (vtop - vvert))) * 0x10000) + (0x10000 - 1); itop = (int)vtop; ibottom = (int)vbottom; for (v=itop ; v<ibottom ; v++) { pspan->count = (u >> 16) - pspan->u; u += u_step; pspan++; } } vtop = vbottom; vvert = vnext; i++; if (i == r_spritedesc.nump) i = 0; } while (i != maxindex); pspan->count = DS_SPAN_LIST_END; // mark the end of the span list } /* ===================== D_SpriteCalculateGradients ===================== */ void D_SpriteCalculateGradients (void) { vec3_t p_normal, p_saxis, p_taxis, p_temp1; float distinv; TransformVector (r_spritedesc.vpn, p_normal); TransformVector (r_spritedesc.vright, p_saxis); TransformVector (r_spritedesc.vup, p_taxis); VectorInverse (p_taxis); distinv = 1.0 / (-DotProduct (modelorg, r_spritedesc.vpn)); d_sdivzstepu = p_saxis[0] * xscaleinv; d_tdivzstepu = p_taxis[0] * xscaleinv; d_sdivzstepv = -p_saxis[1] * yscaleinv; d_tdivzstepv = -p_taxis[1] * yscaleinv; d_zistepu = p_normal[0] * xscaleinv * distinv; d_zistepv = -p_normal[1] * yscaleinv * distinv; d_sdivzorigin = p_saxis[2] - xcenter * d_sdivzstepu - ycenter * d_sdivzstepv; d_tdivzorigin = p_taxis[2] - xcenter * d_tdivzstepu - ycenter * d_tdivzstepv; d_ziorigin = p_normal[2] * distinv - xcenter * d_zistepu - ycenter * d_zistepv; TransformVector (modelorg, p_temp1); sadjust = ((fixed16_t)(DotProduct (p_temp1, p_saxis) * 0x10000 + 0.5)) - (-(cachewidth >> 1) << 16); tadjust = ((fixed16_t)(DotProduct (p_temp1, p_taxis) * 0x10000 + 0.5)) - (-(sprite_height >> 1) << 16); // -1 (-epsilon) so we never wander off the edge of the texture bbextents = (cachewidth << 16) - 1; bbextentt = (sprite_height << 16) - 1; } /* ===================== D_DrawSprite ===================== */ void D_DrawSprite (void) { int i, nump; float ymin, ymax; emitpoint_t *pverts; sspan_t spans[MAXHEIGHT+1]; sprite_spans = spans; // find the top and bottom vertices, and make sure there's at least one scan to // draw ymin = 999999.9; ymax = -999999.9; pverts = r_spritedesc.pverts; for (i=0 ; i<r_spritedesc.nump ; i++) { if (pverts->v < ymin) { ymin = pverts->v; minindex = i; } if (pverts->v > ymax) { ymax = pverts->v; maxindex = i; } pverts++; } ymin = ceil (ymin); ymax = ceil (ymax); if (ymin >= ymax) return; // doesn't cross any scans at all cachewidth = r_spritedesc.pspriteframe->width; sprite_height = r_spritedesc.pspriteframe->height; cacheblock = (byte *)&r_spritedesc.pspriteframe->pixels[0]; // copy the first vertex to the last vertex, so we don't have to deal with // wrapping nump = r_spritedesc.nump; pverts = r_spritedesc.pverts; pverts[nump] = pverts[0]; D_SpriteCalculateGradients (); D_SpriteScanLeftEdge (); D_SpriteScanRightEdge (); D_SpriteDrawSpans (sprite_spans); }