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81 lines
1.8 KiB
81 lines
1.8 KiB
const int MAX_WIDTH = 1024, MAX_HEIGHT = 1024;
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int image[MAX_WIDTH * MAX_HEIGHT], width, height;
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const float PI = 3.14159265359, TWO_PI = 6.28318530718, EPSILON = 1e-6;
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float my_fabs(float x) {
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if (x > 0) return x;
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return -x;
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}
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float p(float x) { return 3 * x - 4 * x * x * x; }
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float my_sin_impl(float x) {
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if (my_fabs(x) <= EPSILON) return x;
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return p(my_sin_impl(x / 3.0));
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}
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float my_sin(float x) {
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if (x > TWO_PI || x < -TWO_PI) {
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int xx = x / TWO_PI;
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x = x - xx * TWO_PI;
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}
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if (x > PI) x = x - TWO_PI;
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if (x < -PI) x = x + TWO_PI;
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return my_sin_impl(x);
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}
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float my_cos(float x) { return my_sin(x + PI / 2); }
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int read_image() {
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if (getch() != 80 || getch() != 50) return -1;
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width = getint();
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height = getint();
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if (width > MAX_WIDTH || height > MAX_HEIGHT || getint() != 255) return -1;
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int y = 0;
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while (y < height) {
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int x = 0;
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while (x < width) {
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image[y * width + x] = getint();
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x = x + 1;
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}
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y = y + 1;
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}
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return 0;
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}
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int rotate(int x, int y, float rad) {
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float sinma = my_sin(rad), cosma = my_cos(rad);
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int hwidth = width / 2, hheight = height / 2;
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int xt = x - hwidth, yt = y - hheight;
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int src_x = xt * cosma - yt * sinma + hwidth,
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src_y = xt * sinma + yt * cosma + hheight;
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if (src_x < 0 || src_x >= width || src_y < 0 || src_y >= height) return 0;
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return image[src_y * width + src_x];
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}
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void write_pgm(float rad) {
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putch(80); putch(50); putch(10); // P2
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putint(width); putch(32); putint(height); putch(32); // width height
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putint(255); putch(10); // 255
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int y = 0;
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while (y < height) {
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int x = 0;
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while (x < width) {
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putint(rotate(x, y, rad));
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putch(32);
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x = x + 1;
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}
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putch(10);
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y = y + 1;
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}
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}
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int main() {
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float rad = getfloat();
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getch();
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if (read_image() < 0) return -1;
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write_pgm(rad);
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return 0;
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}
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