/* Copyright (C) 1997-2001 Id Software, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ // r_aclip.c: clip routines for drawing Alias models directly to the screen #include "sw.h" /* ================ R_Alias_clip_z pfv0 is the unclipped vertex, pfv1 is the z-clipped vertex ================ */ static void R_Alias_clip_z(finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out) { float scale; scale = (ALIAS_Z_CLIP_PLANE - pfv0->xyz[2]) / (pfv1->xyz[2] - pfv0->xyz[2]); out->xyz[0] = pfv0->xyz[0] + (pfv1->xyz[0] - pfv0->xyz[0]) * scale; out->xyz[1] = pfv0->xyz[1] + (pfv1->xyz[1] - pfv0->xyz[1]) * scale; out->xyz[2] = ALIAS_Z_CLIP_PLANE; out->s = pfv0->s + (pfv1->s - pfv0->s) * scale; out->t = pfv0->t + (pfv1->t - pfv0->t) * scale; out->l = pfv0->l + (pfv1->l - pfv0->l) * scale; R_AliasProjectAndClipTestFinalVert(out); } static void R_Alias_clip_left(finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out) { float scale; if (pfv0->v >= pfv1->v) { scale = (float)(r_refdef.vrect.x - pfv0->u) / (pfv1->u - pfv0->u); out->u = pfv0->u + (pfv1->u - pfv0->u) * scale + 0.5; out->v = pfv0->v + (pfv1->v - pfv0->v) * scale + 0.5; out->s = pfv0->s + (pfv1->s - pfv0->s) * scale + 0.5; out->t = pfv0->t + (pfv1->t - pfv0->t) * scale + 0.5; out->l = pfv0->l + (pfv1->l - pfv0->l) * scale + 0.5; out->zi = pfv0->zi + (pfv1->zi - pfv0->zi) * scale + 0.5; } else { scale = (float)(r_refdef.vrect.x - pfv1->u) / (pfv0->u - pfv1->u); out->u = pfv1->u + (pfv0->u - pfv1->u) * scale + 0.5; out->v = pfv1->v + (pfv0->v - pfv1->v) * scale + 0.5; out->s = pfv1->s + (pfv0->s - pfv1->s) * scale + 0.5; out->t = pfv1->t + (pfv0->t - pfv1->t) * scale + 0.5; out->l = pfv1->l + (pfv0->l - pfv1->l) * scale + 0.5; out->zi = pfv1->zi + (pfv0->zi - pfv1->zi) * scale + 0.5; } } static void R_Alias_clip_right(finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out) { float scale; if (pfv0->v >= pfv1->v) { scale = (float)(r_refdef.vrectright - pfv0->u) / (pfv1->u - pfv0->u); out->u = pfv0->u + (pfv1->u - pfv0->u) * scale + 0.5; out->v = pfv0->v + (pfv1->v - pfv0->v) * scale + 0.5; out->s = pfv0->s + (pfv1->s - pfv0->s) * scale + 0.5; out->t = pfv0->t + (pfv1->t - pfv0->t) * scale + 0.5; out->l = pfv0->l + (pfv1->l - pfv0->l) * scale + 0.5; out->zi = pfv0->zi + (pfv1->zi - pfv0->zi) * scale + 0.5; } else { scale = (float)(r_refdef.vrectright - pfv1->u) / (pfv0->u - pfv1->u); out->u = pfv1->u + (pfv0->u - pfv1->u) * scale + 0.5; out->v = pfv1->v + (pfv0->v - pfv1->v) * scale + 0.5; out->s = pfv1->s + (pfv0->s - pfv1->s) * scale + 0.5; out->t = pfv1->t + (pfv0->t - pfv1->t) * scale + 0.5; out->l = pfv1->l + (pfv0->l - pfv1->l) * scale + 0.5; out->zi = pfv1->zi + (pfv0->zi - pfv1->zi) * scale + 0.5; } } static void R_Alias_clip_top(finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out) { float scale; if (pfv0->v >= pfv1->v) { scale = (float)(r_refdef.vrect.y - pfv0->v) / (pfv1->v - pfv0->v); out->u = pfv0->u + (pfv1->u - pfv0->u) * scale + 0.5; out->v = pfv0->v + (pfv1->v - pfv0->v) * scale + 0.5; out->s = pfv0->s + (pfv1->s - pfv0->s) * scale + 0.5; out->t = pfv0->t + (pfv1->t - pfv0->t) * scale + 0.5; out->l = pfv0->l + (pfv1->l - pfv0->l) * scale + 0.5; out->zi = pfv0->zi + (pfv1->zi - pfv0->zi) * scale + 0.5; } else { scale = (float)(r_refdef.vrect.y - pfv1->v) / (pfv0->v - pfv1->v); out->u = pfv1->u + (pfv0->u - pfv1->u) * scale + 0.5; out->v = pfv1->v + (pfv0->v - pfv1->v) * scale + 0.5; out->s = pfv1->s + (pfv0->s - pfv1->s) * scale + 0.5; out->t = pfv1->t + (pfv0->t - pfv1->t) * scale + 0.5; out->l = pfv1->l + (pfv0->l - pfv1->l) * scale + 0.5; out->zi = pfv1->zi + (pfv0->zi - pfv1->zi) * scale + 0.5; } } static void R_Alias_clip_bottom(finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out) { float scale; if (pfv0->v >= pfv1->v) { scale = (float)(r_refdef.vrectbottom - pfv0->v) / (pfv1->v - pfv0->v); out->u = pfv0->u + (pfv1->u - pfv0->u) * scale + 0.5; out->v = pfv0->v + (pfv1->v - pfv0->v) * scale + 0.5; out->s = pfv0->s + (pfv1->s - pfv0->s) * scale + 0.5; out->t = pfv0->t + (pfv1->t - pfv0->t) * scale + 0.5; out->l = pfv0->l + (pfv1->l - pfv0->l) * scale + 0.5; out->zi = pfv0->zi + (pfv1->zi - pfv0->zi) * scale + 0.5; } else { scale = (float)(r_refdef.vrectbottom - pfv1->v) / (pfv0->v - pfv1->v); out->u = pfv1->u + (pfv0->u - pfv1->u) * scale + 0.5; out->v = pfv1->v + (pfv0->v - pfv1->v) * scale + 0.5; out->s = pfv1->s + (pfv0->s - pfv1->s) * scale + 0.5; out->t = pfv1->t + (pfv0->t - pfv1->t) * scale + 0.5; out->l = pfv1->l + (pfv0->l - pfv1->l) * scale + 0.5; out->zi = pfv1->zi + (pfv0->zi - pfv1->zi) * scale + 0.5; } } static int R_AliasClip(finalvert_t *in, finalvert_t *out, int flag, int count, void (*clip)(finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)) { int i, j, k; int flags, oldflags; j = count - 1; k = 0; for (i = 0; i < count; j = i, i++) { oldflags = in[j].flags & flag; flags = in[i].flags & flag; if (flags && oldflags) continue; if (oldflags ^ flags) { clip(&in[j], &in[i], &out[k]); out[k].flags = 0; if (out[k].u < r_refdef.vrect.x) out[k].flags |= ALIAS_LEFT_CLIP; if (out[k].v < r_refdef.vrect.y) out[k].flags |= ALIAS_TOP_CLIP; if (out[k].u > r_refdef.vrectright) out[k].flags |= ALIAS_RIGHT_CLIP; if (out[k].v > r_refdef.vrectbottom) out[k].flags |= ALIAS_BOTTOM_CLIP; k++; } if (!flags) { out[k] = in[i]; k++; } } return k; } /* ================ R_AliasClipTriangle ================ */ void R_AliasClipTriangle(finalvert_t *index0, finalvert_t *index1, finalvert_t *index2) { finalvert_t fv[2][8]; int i, k, pingpong; unsigned clipflags; // copy vertexes and fix seam texture coordinates fv[0][0] = *index0; fv[0][1] = *index1; fv[0][2] = *index2; // clip clipflags = fv[0][0].flags | fv[0][1].flags | fv[0][2].flags; if (clipflags & ALIAS_Z_CLIP) { k = R_AliasClip(fv[0], fv[1], ALIAS_Z_CLIP, 3, R_Alias_clip_z); if (k == 0) return; pingpong = 1; clipflags = fv[1][0].flags | fv[1][1].flags | fv[1][2].flags; } else { pingpong = 0; k = 3; } if (clipflags & ALIAS_LEFT_CLIP) { k = R_AliasClip(fv[pingpong], fv[pingpong ^ 1], ALIAS_LEFT_CLIP, k, R_Alias_clip_left); if (k == 0) return; pingpong ^= 1; } if (clipflags & ALIAS_RIGHT_CLIP) { k = R_AliasClip(fv[pingpong], fv[pingpong ^ 1], ALIAS_RIGHT_CLIP, k, R_Alias_clip_right); if (k == 0) return; pingpong ^= 1; } if (clipflags & ALIAS_BOTTOM_CLIP) { k = R_AliasClip(fv[pingpong], fv[pingpong ^ 1], ALIAS_BOTTOM_CLIP, k, R_Alias_clip_bottom); if (k == 0) return; pingpong ^= 1; } if (clipflags & ALIAS_TOP_CLIP) { k = R_AliasClip(fv[pingpong], fv[pingpong ^ 1], ALIAS_TOP_CLIP, k, R_Alias_clip_top); if (k == 0) return; pingpong ^= 1; } for (i = 0; i < k; i++) { if (fv[pingpong][i].u < r_refdef.vrect.x) fv[pingpong][i].u = r_refdef.vrect.x; else if (fv[pingpong][i].u > r_refdef.vrectright) fv[pingpong][i].u = r_refdef.vrectright; if (fv[pingpong][i].v < r_refdef.vrect.y) fv[pingpong][i].v = r_refdef.vrect.y; else if (fv[pingpong][i].v > r_refdef.vrectbottom) fv[pingpong][i].v = r_refdef.vrectbottom; fv[pingpong][i].flags = 0; } // draw triangles for (i = 1; i < k - 1; i++) { aliastriangleparms.a = &fv[pingpong][0]; aliastriangleparms.b = &fv[pingpong][i]; aliastriangleparms.c = &fv[pingpong][i + 1]; R_DrawTriangle(); } }