94 lines
2.2 KiB
C
94 lines
2.2 KiB
C
#include "AABB.h"
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uint8_t find_1D_overlap(Vector2 l1, Vector2 l2, float* overlap)
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{
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// No Overlap
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if (l1.y <= l2.x || l2.y <= l1.x) return 0;
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if (l1.x >= l2.x && l1.y <= l2.y)
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{
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// Complete Overlap, any direction is possible
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// Cannot give a singular value, but return something anyways
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*overlap = l2.y-l2.x + l1.y-l1.x;
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return 2;
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}
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//Partial overlap
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// x is p1, y is p2
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*overlap = (l2.y > l1.y)? l2.x - l1.y : l2.y - l1.x;
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return 1;
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}
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uint8_t find_AABB_overlap(const Vector2 tl1, const Vector2 sz1, const Vector2 tl2, const Vector2 sz2, Vector2* overlap)
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{
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// Note that we include one extra pixel for checking
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// This avoid overlapping on the border
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Vector2 l1, l2;
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uint8_t overlap_x, overlap_y;
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l1.x = tl1.x;
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l1.y = tl1.x + sz1.x;
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l2.x = tl2.x;
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l2.y = tl2.x + sz2.x;
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overlap_x = find_1D_overlap(l1, l2, &overlap->x);
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l1.x = tl1.y;
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l1.y = tl1.y + sz1.y;
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l2.x = tl2.y;
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l2.y = tl2.y + sz2.y;
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overlap_y = find_1D_overlap(l1, l2, &overlap->y);
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if (overlap_x == 2 && overlap_y == 2) return 2;
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return (overlap_x < overlap_y) ? overlap_x : overlap_y;
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}
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bool point_in_AABB(Vector2 point, Rectangle box)
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{
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return (
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point.x >= box.x
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&& point.y >= box.y
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&& point.x < box.x + box.width
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&& point.y < box.y + box.height
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);
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}
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bool line_in_AABB(Vector2 p1, Vector2 p2, Rectangle box)
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{
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float A = p2.y - p1.y;
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float B = p1.x - p2.x;
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float C = (p2.x * p1.y) - (p1.x * p2.y);
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Vector2 corners[3] =
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{
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{box.x + box.width - 1, box.y},
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{box.x + box.width - 1, box.y + box.height - 1},
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{box.x, box.y + box.height - 1},
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};
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float F = (A * box.x + B * box.y + C);
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uint8_t last_mode = 0;
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if (fabs(F) < 1e-3)
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{
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last_mode = 0;
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}
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else
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{
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last_mode = (F > 0) ? 1 : 2;
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}
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for (uint8_t i = 0; i < 3; ++i)
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{
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F = (A * corners[i].x + B * corners[i].y + C);
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uint8_t mode = 0;
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if (fabs(F) < 1e-3)
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{
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mode = 0;
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}
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else
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{
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mode = (F > 0) ? 1 : 2;
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}
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if (mode != last_mode) return true;
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last_mode = mode;
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}
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return false;
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}
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