95 lines
3.1 KiB
C
95 lines
3.1 KiB
C
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/*
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** The contents of this file are subject to the Mozilla Public License
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** Version 1.1 (the "License"); you may not use this file except in compliance
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** with the License. You may obtain a copy of the License at
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** http://www.mozilla.org/MPL/
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**
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** Software distributed under the License is distributed on an "AS IS" basis,
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** WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
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** the specific language governing rights and limitations under the License.
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*/
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#include "defs.h"
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#include "polygon.h"
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#include "pragmas.h"
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#include "math.h"
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#include "fix.h"
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/*
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** Name: polygon_clip
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** Desc: clip a polygon to a pre-calculated distance table.
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*/
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int polygon_clip(POLYGON dst, POLYGON src, int n, int dist[])
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{
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int r = 0, a, b, t;
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if (n >= 3)
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{
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for (a = n - 1, b = 0; b < n; a = b++)
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{
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if (dist[a] >= 0) dst[r++] = src[a];
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if ((dist[a] ^ dist[b]) < 0)
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{
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VERTEX v1 = src[a], v2 = src[b];
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dst[r].x = v1.x + fixmul(v2.x - v1.x, t = fixdiv(dist[a], dist[a] - dist[b]));
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dst[r].y = v1.y + fixmul(v2.y - v1.y, t);
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dst[r].z = v1.z + fixmul(v2.z - v1.z, t);
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dst[r].u = v1.u + fixmul(v2.u - v1.u, t);
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dst[r].v = v1.v + fixmul(v2.v - v1.v, t);
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dst[r].w = v1.w + fixmul(v2.w - v1.w, t);
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r++;
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}
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}
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}
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return r;
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}
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/*
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** Name: polygon_clip_to_frustum
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** Desc: clip a polygon to the frustrum.
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*/
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int polygon_clip_to_frustum(POLYGON dst, POLYGON src, int n)
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{
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int i;
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int dist[MAX_POLYGON];
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POLYGON tmp;
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//for (i = n; i--; dist[i] = src[i].z - 100 ); n = polygon_clip(dst, src, n, dist); // Front
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//for (i = n; i--; dist[i] = 0x8000000 - tmp[i].z); n = polygon_clip(dst, tmp, n, dist); // Back
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for (i = n; i--; dist[i] = src[i].x + src[i].z); n = polygon_clip(tmp, src, n, dist); // Left
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for (i = n; i--; dist[i] = tmp[i].z - tmp[i].x); n = polygon_clip(dst, tmp, n, dist); // Right
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for (i = n; i--; dist[i] = dst[i].y + dst[i].z); n = polygon_clip(tmp, dst, n, dist); // Top
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for (i = n; i--; dist[i] = tmp[i].z - tmp[i].y); n = polygon_clip(dst, tmp, n, dist); // Bottom
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return n;
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}
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/*
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** Name: polygon_project
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** Desc: project a polygon into screen space. prepare z, u & v for linear interpolation.
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*/
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void polygon_project(POLYGON dst, POLYGON src, int n, int width, int height, SURFACE* surface)
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{
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int cx = i2f(width ) >> 1;
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int cy = i2f(height) >> 1;
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while (n--)
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{
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VERTEX p = src[n];
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p.z += 6; // 6 == 1 in view space.
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dst[n].x = imuldiv(p.x, cx - i2f(0), p.z) + cx - (FRACCEIL >> 1);
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dst[n].y = - imuldiv(p.y, cy - i2f(0), p.z) + cy - (FRACCEIL >> 1);
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dst[n].z = fixinv(p.z);
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dst[n].u = mulscale(p.u + surface->panningx, dst[n].z, surface->repeatx + 18);
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dst[n].v = mulscale(p.v + surface->panningy, dst[n].z, surface->repeaty + 18);
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dst[n].w = i2f(31) - imin((abs(p.x) << 1) + (abs(p.y) << 1) + (p.z << 2), i2f(30));
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}
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}
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