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trianglepacker.h
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trianglepacker.h
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/***********************************************************
* A single header file 3D->2D rect triangle packing lib *
* https://github.com/ands/trianglepacker *
* no warranty implied | use at your own risk *
* author: Andreas Mantler (ands) | last change: 31.08.2016 *
* *
* License: *
* This software is in the public domain. *
* Where that dedication is not recognized, *
* you are granted a perpetual, irrevocable license to copy *
* and modify this file however you want. *
***********************************************************/
#ifndef TRIANGLEPACKER_H
#define TRIANGLEPACKER_H
#ifndef TP_CALLOC
#define TP_CALLOC(count, size) calloc(count, size)
#endif
#ifndef TP_FREE
#define TP_FREE(ptr) free(ptr)
#endif
typedef int tp_bool;
#define TP_FALSE 0
#define TP_TRUE 1
// API
// returns TP_FALSE if triangles do not fit into the rect with the specified size, border and spacing
tp_bool tpPackIntoRect(
const float *positions, int vertexCount,
int width, int height, int border, int spacing,
float *outUVs,
float *outScale3Dto2D);
// returns number of successfully packed vertices
int tpPackWithFixedScaleIntoRect(
const float *positions, int vertexCount, float scale3Dto2D,
int width, int height, int border, int spacing,
float *outUVs);
#endif // TRIANGLEPACKER_H
////////////////////// END OF HEADER //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#ifdef TRIANGLEPACKER_IMPLEMENTATION
#undef TRIANGLEPACKER_IMPLEMENTATION
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <assert.h>
#define TP_SWAP(type, a, b) { type tmp = (a); (a) = (b); (b) = tmp; }
#if defined(_MSC_VER) && !defined(__cplusplus) // TODO: specific versions only?
#define inline __inline
#endif
static inline int tp_mini (int a, int b) { return a < b ? a : b; }
static inline int tp_maxi (int a, int b) { return a > b ? a : b; }
static inline int tp_absi (int a ) { return a < 0 ? -a : a; }
typedef struct tp_vec2 { float x, y; } tp_vec2;
static inline tp_vec2 tp_v2i (int x, int y) { tp_vec2 v = { (float)x, (float)y }; return v; }
static inline tp_vec2 tp_v2 (float x, float y) { tp_vec2 v = { x, y }; return v; }
static inline tp_vec2 tp_mul2 (tp_vec2 a, tp_vec2 b) { return tp_v2(a.x * b.x, a.y * b.y); }
typedef struct tp_vec3 { float x, y, z; } tp_vec3;
static inline tp_vec3 tp_v3 (float x, float y, float z) { tp_vec3 v = { x, y, z }; return v; }
static inline tp_vec3 tp_add3 (tp_vec3 a, tp_vec3 b) { return tp_v3(a.x + b.x, a.y + b.y, a.z + b.z); }
static inline tp_vec3 tp_sub3 (tp_vec3 a, tp_vec3 b) { return tp_v3(a.x - b.x, a.y - b.y, a.z - b.z); }
static inline tp_vec3 tp_scale3 (tp_vec3 a, float b) { return tp_v3(a.x * b, a.y * b, a.z * b); }
static inline tp_vec3 tp_div3 (tp_vec3 a, float b) { return tp_scale3(a, 1.0f / b); }
static inline float tp_dot3 (tp_vec3 a, tp_vec3 b) { return a.x * b.x + a.y * b.y + a.z * b.z; }
static inline float tp_length3sq (tp_vec3 a ) { return a.x * a.x + a.y * a.y + a.z * a.z; }
static inline float tp_length3 (tp_vec3 a ) { return sqrtf(tp_length3sq(a)); }
static inline tp_vec3 tp_normalize3(tp_vec3 a ) { return tp_div3(a, tp_length3(a)); }
typedef struct
{
int Aindex;
short w, x, h, hflip;
// C -
// * | * | h
// * | * |
// B-----+--------A -
// '--x--' |
// '-------w------'
} tp_triangle;
static int tp_triangle_cmp(const void *a, const void *b)
{
tp_triangle *ea = (tp_triangle*)a;
tp_triangle *eb = (tp_triangle*)b;
int dh = eb->h - ea->h;
return dh != 0 ? dh : (eb->w - ea->w);
}
#ifdef TP_DEBUG_OUTPUT
static void tp_line(unsigned char *data, int w, int h,
int x0, int y0, int x1, int y1,
unsigned char r, unsigned char g, unsigned char b)
{
int dx = tp_absi(x1 - x0), sx = x0 < x1 ? 1 : -1;
int dy = tp_absi(y1 - y0), sy = y0 < y1 ? 1 : -1;
int err = (dx > dy ? dx : -dy) / 2, e2;
for(;;)
{
unsigned char *p = data + (y0 * w + x0) * 3;
p[0] = r; p[1] = g; p[2] = b;
if (x0 == x1 && y0 == y1) break;
e2 = err;
if (e2 > -dx) { err -= dy; x0 += sx; }
if (e2 < dy) { err += dx; y0 += sy; }
}
}
static tp_bool tp_save_bgr_tga(const char *filename, const unsigned char *image, int w, int h)
{
unsigned char header[18] = { 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, w & 0xff, (w >> 8) & 0xff, h & 0xff, (h >> 8) & 0xff, 24, 0 };
#if defined(_MSC_VER) && _MSC_VER >= 1400
FILE *file;
if (fopen_s(&file, filename, "wb") != 0) return TP_FALSE;
#else
FILE *file = fopen(filename, "wb");
if (!file) return TP_FALSE;
#endif
fwrite(header, 1, sizeof(header), file);
fwrite(image, 1, w * h * 3 , file);
fclose(file);
return TP_TRUE;
}
#endif
static void tp_wave_surge(int *wave, int right, int x0, int y0, int x1, int y1)
{
int dx = tp_absi(x1 - x0), sx = x0 < x1 ? 1 : -1;
int dy = tp_absi(y1 - y0), sy = y0 < y1 ? 1 : -1;
int err = (dx > dy ? dx : -dy) / 2, e2;
for(;;)
{
if (right)
wave[y0] = x0 > wave[y0] ? x0 : wave[y0];
else
wave[y0] = x0 < wave[y0] ? x0 : wave[y0];
if (x0 == x1 && y0 == y1) break;
e2 = err;
if (e2 > -dx) { err -= dy; x0 += sx; }
if (e2 < dy) { err += dx; y0 += sy; }
}
}
static int tp_wave_wash_up(int *wave, int right, int height, int y0, int x1, int y1, int spacing)
{
int x0 = 0;
int dx = tp_absi(x1 - x0), sx = x0 < x1 ? 1 : -1;
int dy = tp_absi(y1 - y0), sy = y0 < y1 ? 1 : -1;
int err = (dx > dy ? dx : -dy) / 2, e2;
int x = wave[y0];
for(;;)
{
int xDistance = wave[y0] - x0 - x;
for (int y = tp_maxi(y0 - spacing, 0); y <= tp_mini(y0 + spacing, height - 1); y++)
xDistance = right ? tp_maxi(wave[y] - x0 - x, xDistance) : tp_mini(wave[y] - x0 - x, xDistance);
if ((right && xDistance > 0) || (!right && xDistance < 0))
x += xDistance;
if (x0 == x1 && y0 == y1) break;
e2 = err;
if (e2 > -dx) { err -= dy; x0 += sx; }
if (e2 < dy) { err += dx; y0 += sy; }
}
return x;
}
int tpPackWithFixedScaleIntoRect(const float *positions, int vertexCount, float scale3Dto2D, int width, int height, int border, int spacing, float *outUVs)
{
tp_triangle *tris = (tp_triangle*)TP_CALLOC(vertexCount / 3, sizeof(tp_triangle));
tp_vec3 *p = (tp_vec3*)positions;
tp_vec2 *uv = (tp_vec2*)outUVs;
for (int i = 0; i < vertexCount / 3; i++)
{
tp_vec3 tp[3], tv[3];
tp[0] = tp_scale3(p[i * 3 + 0], scale3Dto2D);
tp[1] = tp_scale3(p[i * 3 + 1], scale3Dto2D);
tp[2] = tp_scale3(p[i * 3 + 2], scale3Dto2D);
tv[0] = tp_sub3(tp[1], tp[0]);
tv[1] = tp_sub3(tp[2], tp[1]);
tv[2] = tp_sub3(tp[0], tp[2]);
float tvlsq[3] = { tp_length3sq(tv[0]), tp_length3sq(tv[1]), tp_length3sq(tv[2]) };
// find long edge
int maxi; float maxl = tvlsq[0]; maxi = 0;
if (tvlsq[1] > maxl) { maxl = tvlsq[1]; maxi = 1; }
if (tvlsq[2] > maxl) { maxl = tvlsq[2]; maxi = 2; }
int nexti = (maxi + 1) % 3;
// measure triangle
float w = sqrtf(maxl);
float x = -tp_dot3(tv[maxi], tv[nexti]) / w;
float h = tp_length3(tp_sub3(tp_add3(tv[maxi], tv[nexti]), tp_scale3(tp_normalize3(tv[maxi]), w - x)));
// store entry
tp_triangle *e = tris + i;
e->Aindex = i * 3 + maxi;
e->w = (int)ceilf(w);
e->x = (int)ceilf(x);
e->h = (int)ceilf(h);
e->hflip = 0;
}
qsort(tris, vertexCount / 3, sizeof(tp_triangle), tp_triangle_cmp);
tp_vec2 uvScale = tp_v2(1.0f / width, 1.0f / height);
#ifdef TP_DEBUG_OUTPUT
unsigned char *data;
if (uv)
data = (unsigned char*)TP_CALLOC(width * height, 3);
#endif
int processed;
int *waves[2];
waves[0] = (int*)TP_CALLOC(2 * height, sizeof(int));
waves[1] = waves[0] + height;
for (int i = 0; i < height; i++)
{
waves[0][i] = width - 1;// - border;
waves[1][i] = border;
}
int pass = 0;
int row_y = border;
int row_h = tris[0].h;
int vflip = 0;
for (processed = 0; processed < vertexCount / 3; processed++)
{
tp_triangle *e = tris + processed;
int ymin, ystart, yend, xmin[2], x, hflip;
retry:
ymin = vflip ? row_y + row_h - e->h : row_y;
ystart = vflip ? ymin + e->h : ymin;
yend = vflip ? ymin : ymin + e->h;
// calculate possible x values for the triangle in the current row
hflip = processed & 1; // seems to work better than the heuristics below!?
if (pass < 3) // left to right (first three passes)
{
xmin[0] = tp_wave_wash_up(waves[1], 1, height, ystart, e->x, yend, spacing);
xmin[1] = tp_wave_wash_up(waves[1], 1, height, ystart, e->w - e->x, yend, spacing); // flipped horizontally
//hflip = (xmin[1] < xmin[0] || (xmin[1] == xmin[0] && e->x > e->w / 2)) ? 1 : 0;
}
else if (pass < 5) // right to left (last two passes)
{ // TODO: fix spacing!
xmin[0] = tp_wave_wash_up(waves[0], 0, height, ystart, - e->x, yend, spacing) - e->w - 1;
xmin[1] = tp_wave_wash_up(waves[0], 0, height, ystart, -e->w + e->x, yend, spacing) - e->w - 1; // flipped horizontally
//hflip = (xmin[1] > xmin[0] || (xmin[1] == xmin[0] && e->x < e->w / 2)) ? 1 : 0;
}
else
goto finish;
// execute hflip (and choose best x)
e->x = hflip ? e->w - e->x : e->x;
e->hflip ^= hflip;
x = xmin[hflip];
// check if it fits into the specified rect
// (else advance to next row or do another pass over the rect)
if (x + e->w + border >= width || x < border)
{
row_y += row_h + spacing + 1; // next row
row_h = e->h;
if (row_y + row_h + border >= height)
{
++pass; // next pass
row_y = border;
}
goto retry;
}
// found a space for the triangle. update waves
tp_wave_surge(waves[0], 0, x - spacing - 1, ystart, x + e->x - spacing - 1, yend); // left side
tp_wave_surge(waves[1], 1, x + e->w + spacing + 1, ystart, x + e->x + spacing + 1, yend); // right side
// calc & store UVs
if (uv)
{
#ifdef TP_DEBUG_OUTPUT
tp_line(data, width, height, x , ystart, x + e->w, ystart, 255, 255, 255);
tp_line(data, width, height, x , ystart, x + e->x, yend , 255, 255, 255);
tp_line(data, width, height, x + e->w, ystart, x + e->x, yend , 255, 255, 255);
#endif
int tri = e->Aindex - (e->Aindex % 3);
int Ai = e->Aindex;
int Bi = tri + ((e->Aindex + 1) % 3);
int Ci = tri + ((e->Aindex + 2) % 3);
if (e->hflip) TP_SWAP(int, Ai, Bi);
uv[Ai] = tp_mul2(tp_v2i(x + e->w, ystart), uvScale);
uv[Bi] = tp_mul2(tp_v2i(x , ystart), uvScale);
uv[Ci] = tp_mul2(tp_v2i(x + e->x, yend ), uvScale);
}
vflip = !vflip;
}
finish:
#ifdef TP_DEBUG_OUTPUT
if (uv)
{
/*for (int i = 0; i < height; i++)
{
// left
int x = waves[0][i];// +spacing;
while (x >= 0)
data[(i * width + x--) * 3 + 2] = 255;
// right
x = waves[1][i] - spacing;
while (x < width)
data[(i * width + x++) * 3] = 255;
}*/
if (tp_save_bgr_tga("debug_triangle_packing.tga", data, width, height))
printf("Saved debug_triangle_packing.tga\n");
TP_FREE(data);
}
#endif
TP_FREE(waves[0]);
TP_FREE(tris);
return processed * 3;
}
tp_bool tpPackIntoRect(const float *positions, int vertexCount, int width, int height, int border, int spacing, float *outUVs, float *outScale3Dto2D)
{
float testScale = 1.0f;
int processed = tpPackWithFixedScaleIntoRect(positions, vertexCount, testScale, width, height, border, spacing, 0);
int increase = processed < vertexCount ? 0 : 1;
float lastFitScale = 0.0f;
float multiplicator = 0.5f;
if (increase)
{
while (!(processed < vertexCount))
{
testScale *= 2.0f;
//printf("inc testing scale %f\n", testScale);
processed = tpPackWithFixedScaleIntoRect(positions, vertexCount, testScale, width, height, border, spacing, 0);
}
lastFitScale = testScale / 2.0f;
//printf("inc scale %f fits\n", lastFitScale);
multiplicator = 0.75f;
}
for (int j = 0; j < 16; j++)
{
//printf("dec multiplicator %f\n", multiplicator);
for (int i = 0; processed < vertexCount && i < 2; i++)
{
testScale *= multiplicator;
//printf("dec testing scale %f\n", testScale);
processed = tpPackWithFixedScaleIntoRect(positions, vertexCount, testScale, width, height, border, spacing, 0);
}
if (!(processed < vertexCount))
{
processed = 0;
//printf("scale %f fits\n", testScale);
lastFitScale = testScale;
testScale /= multiplicator;
multiplicator = (multiplicator + 1.0f) * 0.5f;
}
}
if (lastFitScale > 0.0f)
{
*outScale3Dto2D = lastFitScale;
processed = tpPackWithFixedScaleIntoRect(positions, vertexCount, lastFitScale, width, height, border, spacing, outUVs);
assert(processed == vertexCount);
return TP_TRUE;
}
return TP_FALSE;
}
#endif // TRIANGLEPACKER_IMPLEMENTATION