158 lines
6.5 KiB
C
158 lines
6.5 KiB
C
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// Copyright 2013 Howling Moon Software. All rights reserved.
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// See http://chipmunk2d.net/legal.php for more information.
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#include <stdlib.h>
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#include <stdio.h>
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#include <math.h>
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#include "chipmunk/chipmunk.h"
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#include "chipmunk/cpMarch.h"
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typedef void (*cpMarchCellFunc)(
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cpFloat t, cpFloat a, cpFloat b, cpFloat c, cpFloat d,
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cpFloat x0, cpFloat x1, cpFloat y0, cpFloat y1,
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cpMarchSegmentFunc segment, void *segment_data
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);
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// The looping and sample caching code is shared between cpMarchHard() and cpMarchSoft().
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static void
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cpMarchCells(
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cpBB bb, unsigned long x_samples, unsigned long y_samples, cpFloat t,
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cpMarchSegmentFunc segment, void *segment_data,
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cpMarchSampleFunc sample, void *sample_data,
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cpMarchCellFunc cell
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){
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cpFloat x_denom = 1.0/(cpFloat)(x_samples - 1);
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cpFloat y_denom = 1.0/(cpFloat)(y_samples - 1);
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// TODO range assertions and short circuit for 0 sized windows.
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// Keep a copy of the previous row to avoid double lookups.
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cpFloat *buffer = (cpFloat *)cpcalloc(x_samples, sizeof(cpFloat));
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for(unsigned long i=0; i<x_samples; i++) buffer[i] = sample(cpv(cpflerp(bb.l, bb.r, i*x_denom), bb.b), sample_data);
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for(unsigned long j=0; j<y_samples-1; j++){
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cpFloat y0 = cpflerp(bb.b, bb.t, (j+0)*y_denom);
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cpFloat y1 = cpflerp(bb.b, bb.t, (j+1)*y_denom);
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cpFloat a, b = buffer[0];
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cpFloat c, d = sample(cpv(bb.l, y1), sample_data);
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buffer[0] = d;
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for(unsigned long i=0; i<x_samples-1; i++){
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cpFloat x0 = cpflerp(bb.l, bb.r, (i+0)*x_denom);
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cpFloat x1 = cpflerp(bb.l, bb.r, (i+1)*x_denom);
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a = b; b = buffer[i + 1];
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c = d; d = sample(cpv(x1, y1), sample_data);
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buffer[i + 1] = d;
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cell(t, a, b, c, d, x0, x1, y0, y1, segment, segment_data);
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}
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}
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cpfree(buffer);
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}
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// TODO should flip this around eventually.
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static inline void
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seg(cpVect v0, cpVect v1, cpMarchSegmentFunc f, void *data)
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{
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if(!cpveql(v0, v1)) f(v1, v0, data);
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}
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// Lerps between two positions based on their sample values.
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static inline cpFloat
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midlerp(cpFloat x0, cpFloat x1, cpFloat s0, cpFloat s1, cpFloat t)
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{
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return cpflerp(x0, x1, (t - s0)/(s1 - s0));
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}
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static void
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cpMarchCellSoft(
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cpFloat t, cpFloat a, cpFloat b, cpFloat c, cpFloat d,
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cpFloat x0, cpFloat x1, cpFloat y0, cpFloat y1,
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cpMarchSegmentFunc segment, void *segment_data
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){
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// TODO this switch part is super expensive, can it be NEONized?
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switch((a>t)<<0 | (b>t)<<1 | (c>t)<<2 | (d>t)<<3){
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case 0x1: seg(cpv(x0, midlerp(y0,y1,a,c,t)), cpv(midlerp(x0,x1,a,b,t), y0), segment, segment_data); break;
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case 0x2: seg(cpv(midlerp(x0,x1,a,b,t), y0), cpv(x1, midlerp(y0,y1,b,d,t)), segment, segment_data); break;
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case 0x3: seg(cpv(x0, midlerp(y0,y1,a,c,t)), cpv(x1, midlerp(y0,y1,b,d,t)), segment, segment_data); break;
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case 0x4: seg(cpv(midlerp(x0,x1,c,d,t), y1), cpv(x0, midlerp(y0,y1,a,c,t)), segment, segment_data); break;
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case 0x5: seg(cpv(midlerp(x0,x1,c,d,t), y1), cpv(midlerp(x0,x1,a,b,t), y0), segment, segment_data); break;
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case 0x6: seg(cpv(midlerp(x0,x1,a,b,t), y0), cpv(x1, midlerp(y0,y1,b,d,t)), segment, segment_data);
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seg(cpv(midlerp(x0,x1,c,d,t), y1), cpv(x0, midlerp(y0,y1,a,c,t)), segment, segment_data); break;
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case 0x7: seg(cpv(midlerp(x0,x1,c,d,t), y1), cpv(x1, midlerp(y0,y1,b,d,t)), segment, segment_data); break;
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case 0x8: seg(cpv(x1, midlerp(y0,y1,b,d,t)), cpv(midlerp(x0,x1,c,d,t), y1), segment, segment_data); break;
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case 0x9: seg(cpv(x0, midlerp(y0,y1,a,c,t)), cpv(midlerp(x0,x1,a,b,t), y0), segment, segment_data);
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seg(cpv(x1, midlerp(y0,y1,b,d,t)), cpv(midlerp(x0,x1,c,d,t), y1), segment, segment_data); break;
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case 0xA: seg(cpv(midlerp(x0,x1,a,b,t), y0), cpv(midlerp(x0,x1,c,d,t), y1), segment, segment_data); break;
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case 0xB: seg(cpv(x0, midlerp(y0,y1,a,c,t)), cpv(midlerp(x0,x1,c,d,t), y1), segment, segment_data); break;
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case 0xC: seg(cpv(x1, midlerp(y0,y1,b,d,t)), cpv(x0, midlerp(y0,y1,a,c,t)), segment, segment_data); break;
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case 0xD: seg(cpv(x1, midlerp(y0,y1,b,d,t)), cpv(midlerp(x0,x1,a,b,t), y0), segment, segment_data); break;
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case 0xE: seg(cpv(midlerp(x0,x1,a,b,t), y0), cpv(x0, midlerp(y0,y1,a,c,t)), segment, segment_data); break;
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default: break; // 0x0 and 0xF
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}
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}
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void
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cpMarchSoft(
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cpBB bb, unsigned long x_samples, unsigned long y_samples, cpFloat t,
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cpMarchSegmentFunc segment, void *segment_data,
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cpMarchSampleFunc sample, void *sample_data
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){
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cpMarchCells(bb, x_samples, y_samples, t, segment, segment_data, sample, sample_data, cpMarchCellSoft);
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}
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// TODO should flip this around eventually.
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static inline void
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segs(cpVect a, cpVect b, cpVect c, cpMarchSegmentFunc f, void *data)
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{
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seg(b, c, f, data);
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seg(a, b, f, data);
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}
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static void
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cpMarchCellHard(
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cpFloat t, cpFloat a, cpFloat b, cpFloat c, cpFloat d,
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cpFloat x0, cpFloat x1, cpFloat y0, cpFloat y1,
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cpMarchSegmentFunc segment, void *segment_data
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){
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// midpoints
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cpFloat xm = cpflerp(x0, x1, 0.5f);
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cpFloat ym = cpflerp(y0, y1, 0.5f);
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switch((a>t)<<0 | (b>t)<<1 | (c>t)<<2 | (d>t)<<3){
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case 0x1: segs(cpv(x0, ym), cpv(xm, ym), cpv(xm, y0), segment, segment_data); break;
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case 0x2: segs(cpv(xm, y0), cpv(xm, ym), cpv(x1, ym), segment, segment_data); break;
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case 0x3: seg(cpv(x0, ym), cpv(x1, ym), segment, segment_data); break;
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case 0x4: segs(cpv(xm, y1), cpv(xm, ym), cpv(x0, ym), segment, segment_data); break;
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case 0x5: seg(cpv(xm, y1), cpv(xm, y0), segment, segment_data); break;
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case 0x6: segs(cpv(xm, y0), cpv(xm, ym), cpv(x0, ym), segment, segment_data);
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segs(cpv(xm, y1), cpv(xm, ym), cpv(x1, ym), segment, segment_data); break;
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case 0x7: segs(cpv(xm, y1), cpv(xm, ym), cpv(x1, ym), segment, segment_data); break;
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case 0x8: segs(cpv(x1, ym), cpv(xm, ym), cpv(xm, y1), segment, segment_data); break;
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case 0x9: segs(cpv(x1, ym), cpv(xm, ym), cpv(xm, y0), segment, segment_data);
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segs(cpv(x0, ym), cpv(xm, ym), cpv(xm, y1), segment, segment_data); break;
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case 0xA: seg(cpv(xm, y0), cpv(xm, y1), segment, segment_data); break;
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case 0xB: segs(cpv(x0, ym), cpv(xm, ym), cpv(xm, y1), segment, segment_data); break;
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case 0xC: seg(cpv(x1, ym), cpv(x0, ym), segment, segment_data); break;
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case 0xD: segs(cpv(x1, ym), cpv(xm, ym), cpv(xm, y0), segment, segment_data); break;
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case 0xE: segs(cpv(xm, y0), cpv(xm, ym), cpv(x0, ym), segment, segment_data); break;
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default: break; // 0x0 and 0xF
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}
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}
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void
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cpMarchHard(
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cpBB bb, unsigned long x_samples, unsigned long y_samples, cpFloat t,
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cpMarchSegmentFunc segment, void *segment_data,
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cpMarchSampleFunc sample, void *sample_data
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){
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cpMarchCells(bb, x_samples, y_samples, t, segment, segment_data, sample, sample_data, cpMarchCellHard);
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}
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