39 lines
1.1 KiB
C++
39 lines
1.1 KiB
C++
#include <algorithm>
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#include <cmath>
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#include <cstdio>
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#include <cstdlib>
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void write_ppm_image(int *data, int width, int height, const char *filename, int max_iterations)
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{
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FILE *fp = fopen(filename, "wb");
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if (!fp)
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{
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perror("fopen() failed");
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exit(EXIT_FAILURE);
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}
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// write ppm header
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fprintf(fp, "P6\n");
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fprintf(fp, "%d %d\n", width, height);
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fprintf(fp, "255\n");
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for (int i = 0; i < width * height; ++i)
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{
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// Clamp iteration count for this pixel, then scale the value
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// to 0-1 range. Raise resulting value to a power (<1) to
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// increase brightness of low iteration count
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// pixels. a.k.a. Make things look cooler.
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float mapped = std::pow(
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std::min(static_cast<float>(max_iterations), static_cast<float>(data[i])) / 256.f, .5f);
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// convert back into 0-255 range, 8-bit channels
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unsigned char result = static_cast<unsigned char>(255.f * mapped);
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for (int j = 0; j < 3; ++j)
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fputc(result, fp);
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}
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fclose(fp);
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printf("Wrote image file %s\n", filename);
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}
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