44 lines
932 B
C
44 lines
932 B
C
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#include "animation.h"
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line_t line_new(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1) {
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uint8_t dx = x1 - x0;
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int8_t dy = y1 - y0;
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int8_t inc = dy > 0 ? 1 : dy == 0 ? 0 : -1;
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int8_t m = 2 * dy;
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int8_t error = 0;
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if (m > 0) {
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error = m - dx;
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} else {
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error = m + dx;
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}
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return (line_t){ .y = y0, .m = m, .error = error, .inc = inc, .dx = dx };
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}
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uint8_t line_next(line_t *slope) {
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slope->error += slope->m;
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if (slope->m > 0) {
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if (slope->error >= 0) {
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slope->y += slope->inc;
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slope->error -= 2 * slope->dx;
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}
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} else {
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if (slope->error <= 0) {
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slope->y += slope->inc;
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slope->error += 2 * slope->dx;
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}
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}
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return slope->y;
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}
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/*
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void line_print(line_t *line) {
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printf("y: %d\tm: %d\terror: %d\tinc: %d\t:dx: %d\n", line->y, line->m, line->error, line->inc, line->dx);
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}
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*/
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