git.mutantstargoat.com Git - gbajam21/blob - tools/tungen.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <stdint.h>
   4 #include <math.h>
   5
   6 struct vec2 {
   7         float x, y;
   8 };
   9
  10 int main(int argc, char **argv)
  11 {
  12         int i, j, imgrad, xsz = 240, ysz = 160, texsz = 128;
  13         struct vec2 *tunbuf, *tun;
  14         float aspect, prev_r;
  15         struct vec2 *buf, *ptr;
  16
  17         for(i=1; i<argc; i++) {
  18                 if(argv[i][0] == '-') {
  19                         if(argv[i][2] != 0) goto invalopt;
  20                         switch(argv[i][1]) {
  21                         case 's':
  22                                 if(sscanf(argv[++i], "%dx%d", &xsz, &ysz) != 2 || xsz <= 1 || ysz <= 1) {
  23                                         fprintf(stderr, "-s must be followed by WxH\n");
  24                                         return 1;
  25                                 }
  26                                 break;
  27
  28                         case 't':
  29                                 if(!(texsz = atoi(argv[++i])) || texsz > 256) {
  30                                         fprintf(stderr, "-t must be followed by the texture size (1-256)\n");
  31                                         return 1;
  32                                 }
  33                                 break;
  34
  35                         default:
  36                                 goto invalopt;
  37                         }
  38                 } else {
  39 invalopt:       fprintf(stderr, "invalid argument: %s\n", argv[i]);
  40                         return 1;
  41                 }
  42         }
  43
  44         if(!(buf = malloc(xsz * ysz * sizeof *buf))) {
  45                 perror("failed to allocate buffer");
  46                 return 1;
  47         }
  48         imgrad = sqrt(xsz * xsz + ysz * ysz);
  49
  50 #define UDIV    2048
  51 #define VDIV    32768
  52         prev_r = 0.0f;
  53         for(i=0; i<VDIV; i++) {
  54                 float v = (float)(VDIV - i) / (float)VDIV;
  55                 float r = 4.0 / v + 16;
  56                 float z = v * 400.0f;
  57
  58                 /* don't bother drawing rings < 1 pixel apart */
  59                 if(fabs(r - prev_r) < 0.05) continue;
  60
  61                 for(j=0; j<UDIV; j++) {
  62                         float u = (float)j / (float)(UDIV - 1);
  63                         float theta = 2.0f * u * M_PI;
  64
  65                         int x = (int)(cos(theta) * r - z) + xsz / 2;
  66                         int y = (int)(sin(theta) * r) + ysz / 2;
  67
  68                         if(x >= 0 && x < xsz && y >= 0 && y < ysz) {
  69                                 ptr = buf + y * xsz + x;
  70                                 ptr->x = u;
  71                                 ptr->y = v * 8;
  72                         }
  73                 }
  74                 prev_r = r;
  75         }
  76
  77         FILE *fp = fopen("tun_preview.ppm", "wb");
  78         if(fp) {
  79                 fprintf(fp, "P6\n%d %d\n255\n", xsz, ysz);
  80         }
  81
  82         aspect = (float)xsz / (float)ysz;
  83
  84         ptr = buf;
  85         for(i=0; i<ysz; i++) {
  86                 for(j=0; j<xsz; j++) {
  87                         float u = ptr->x;
  88                         float v = ptr->y;
  89                         int r = (int)(u * 8.0 * 255.0f) & 0xff;
  90                         int b = (int)(v * 8.0 * 255.0f) & 0xff;
  91
  92                         ptr++;
  93
  94                         uint16_t out = ((uint16_t)(u * 255.0f) & 0xff) |
  95                                 (((uint16_t)(v * 255.0f) & 0xff) << 8);
  96                         fwrite(&out, sizeof out, 1, stdout);
  97
  98                         if(fp) {
  99                                 fputc(r, fp);
 100                                 fputc(0, fp);
 101                                 fputc(b, fp);
 102                         }
 103                 }
 104         }
 105         fflush(stdout);
 106
 107         if(fp) fclose(fp);
 108         return 0;
 109 }