mirror of
https://github.com/RetroPortingToolKit/psxrecomp
synced 2026-10-26 10:19:47 -04:00
Matthew Stanley
53 lines
1.8 KiB
C
53 lines
1.8 KiB
C
#ifndef PSX_GPU_PROJECTIVE_CLIP_H
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#define PSX_GPU_PROJECTIVE_CLIP_H
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/* Clip before dividing by signed camera depth. Attributes follow the same
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* edge parameter, so clipped triangles retain their original texture plane. */
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typedef struct PSXProjectedVertex {
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double x, y, z, u, v, r, g, b;
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} PSXProjectedVertex;
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static inline PSXProjectedVertex psx_projective_lerp(
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PSXProjectedVertex a, PSXProjectedVertex b, double t) {
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PSXProjectedVertex p;
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#define LERP(f) p.f = a.f + (b.f-a.f)*t
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LERP(x); LERP(y); LERP(z); LERP(u); LERP(v);
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LERP(r); LERP(g); LERP(b);
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#undef LERP
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return p;
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}
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static inline double psx_projective_distance(PSXProjectedVertex p, int plane,
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double left, double right, double top, double bottom) {
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switch (plane) {
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case 0: return p.z - 1.0;
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case 1: return p.x - left*p.z;
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case 2: return right*p.z - p.x;
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case 3: return p.y - top*p.z;
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default: return bottom*p.z - p.y;
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}
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}
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static inline int psx_projective_clip_triangle(const PSXProjectedVertex in[3],
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PSXProjectedVertex out[12], double left, double right, double top, double bottom) {
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PSXProjectedVertex a[12], b[12];
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int n=3;
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for (int i=0;i<3;++i) a[i]=in[i];
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for (int plane=0;plane<5 && n;++plane) {
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int m=0;
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PSXProjectedVertex prev=a[n-1];
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double dp=psx_projective_distance(prev,plane,left,right,top,bottom);
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for (int i=0;i<n;++i) {
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PSXProjectedVertex cur=a[i];
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double dc=psx_projective_distance(cur,plane,left,right,top,bottom);
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if ((dp>=0)!=(dc>=0))
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b[m++]=psx_projective_lerp(prev,cur,dp/(dp-dc));
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if (dc>=0) b[m++]=cur;
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prev=cur; dp=dc;
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}
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n=m;
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for (int i=0;i<n;++i) a[i]=b[i];
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}
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for (int i=0;i<n;++i) out[i]=a[i];
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return n;
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}
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#endif
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