#include <stdio.h>
#include <stdlib.h>
+#include <string.h>
#include <stdint.h>
#include <math.h>
+struct vec2 {
+ int x, y;
+};
+
int main(int argc, char **argv)
{
- int i, j, xsz = 240, ysz = 160, texsz = 128;
+ int i, j, frm, imgrad, out_nlines, xsz = 240, ysz = 160, texsz = 128;
+ int half_y = 0;
+ int center = 0;
struct vec2 *tunbuf, *tun;
- float aspect;
+ float prev_r;
+ struct vec2 *buf, *ptr;
+ char *endp;
+ int num_frames = 1;
for(i=1; i<argc; i++) {
if(argv[i][0] == '-') {
}
break;
+ case 'y':
+ half_y = 1;
+ break;
+
+ case 'c':
+ if(!argv[++i]) {
+ fprintf(stderr, "-c must be followed by a center pixel\n");
+ return 1;
+ }
+ center = strtol(argv[i], &endp, 10);
+ if(endp == argv[i]) {
+ fprintf(stderr, "-c invalid center position: %s\n", argv[i]);
+ return 1;
+ }
+ break;
+
+ case 'n':
+ if(!argv[++i]) {
+ fprintf(stderr, "-n must be followed by the number of frames\n");
+ return 1;
+ }
+ if(!(num_frames = atoi(argv[i]))) {
+ fprintf(stderr, "-n invalid number of frames: %s\n", argv[i]);
+ return 1;
+ }
+ break;
+
default:
goto invalopt;
}
}
}
+ out_nlines = half_y ? ysz / 2 : ysz;
+
+ if(!(buf = malloc(xsz * ysz * sizeof *buf))) {
+ perror("failed to allocate buffer");
+ return 1;
+ }
+ imgrad = sqrt(xsz * xsz + ysz * ysz);
+
FILE *fp = fopen("tun_preview.ppm", "wb");
if(fp) {
- fprintf(fp, "P6\n%d %d\n255\n", xsz, ysz);
+ fprintf(fp, "P6\n%d %d\n255\n", xsz, out_nlines * num_frames);
}
- aspect = (float)xsz / (float)ysz;
- tun = tunbuf;
- for(i=0; i<ysz; i++) {
- float y = 2.0f * (float)i / (float)(ysz - 1) - 1.0f;
- for(j=0; j<xsz; j++) {
- float x = (2.0f * (float)j / (float)(xsz - 1) - 1.0f) * aspect;
+ for(frm=0; frm<num_frames; frm++) {
+ int coffs = num_frames > 1 ? frm * center / (num_frames - 1) : center;
+
+ memset(buf, 0xff, xsz * ysz * sizeof *buf);
- float r = sqrt(x * x + y * y);
- float theta = atan2(y, x);
+#define UDIV 2048
+#define VDIV 32768
+ prev_r = 0.0f;
+#pragma omp parallel for private(i, j, prev_r, ptr) schedule(dynamic)
+ for(i=0; i<VDIV; i++) {
+ float v = (float)(VDIV - i) / (float)VDIV;
+ float r = 4.0 / v + 16;
+ float z = v * coffs;
- float u = 0.5f * theta / M_PI + 0.5f;
- float v = r;
+ /* don't bother drawing rings < 1 pixel apart */
+ if(r < 0 || fabs(r - prev_r) < 0.05) continue;
- uint32_t out = ((uint32_t)(u * 65535.0f) & 0xffff) |
- (((uint32_t)(v * 65535.0f) & 0xffff) << 16);
- fwrite(&out, sizeof out, 1, stdout);
+ for(j=0; j<UDIV; j++) {
+ float u = (float)j / (float)(UDIV - 1);
+ float theta = 2.0f * u * M_PI;
- if(fp) {
- int cr = (int)(u * 2048.0f) & 0xff;
- int cb = (int)(r * 2048.0f) & 0xff;
- fputc(cr, fp);
- fputc(0, fp);
- fputc(cb, fp);
+ int x = (int)(cos(theta) * r - z) + xsz / 2;
+ int y = (int)(sin(theta) * r) + ysz / 2;
+
+ if(x >= 0 && x < xsz && y >= 0 && y < ysz) {
+ ptr = buf + y * xsz + x;
+ ptr->x = (j << 8) / UDIV;
+ ptr->y = ((VDIV - i - 1) << 10) / VDIV;
+ }
}
+ prev_r = r;
}
+
+ ptr = buf;
+ for(i=0; i<out_nlines; i++) {
+ for(j=0; j<xsz; j++) {
+ int u = ptr->x;
+ int v = ptr->y;
+ int r = u & 0x3f;
+ int g = (v >> 2) & 0xff;
+
+ /*if(v > 2.0) r = g = b = 0;*/
+
+ ptr++;
+
+ uint16_t out = ((uint16_t)u & 0x3f) | (((uint16_t)v & 0x3ff) << 6);
+ fwrite(&out, sizeof out, 1, stdout);
+
+ if(fp) {
+ fputc(r, fp);
+ fputc(g, fp);
+ fputc(0, fp);
+ }
+ }
+ }
+
}
fflush(stdout);