130 lines
2.6 KiB
C
130 lines
2.6 KiB
C
//---
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// geometry: Geometry utilities
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//---
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#pragma once
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#include "fixed.h"
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#include <stdbool.h>
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#include <stdlib.h>
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/* Directions */
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enum { UP=0, RIGHT=1, DOWN=2, LEFT=3 };
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/* Orientations */
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enum { VERTICAL=0, HORIZONTAL=1, CEILING=2 };
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//---
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// Geometric primitives; the engine types are the fixed-point versions, but the
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// integer versions are useful as input/output, either to specify model data or
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// to draw to screen using pixel-based methods.
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//---
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typedef struct
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{
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fixed_t x, y;
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} vec2;
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typedef struct
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{
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int16_t x, y;
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} ivec2;
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typedef struct
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{
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/* Left edge, right edge */
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fixed_t l, r;
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/* Top edge, bottom edge */
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fixed_t t, b;
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} rect;
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typedef struct
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{
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int16_t l, r;
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int16_t t, b;
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} irect;
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/* Functions converting integer shapes to fixed-point. */
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vec2 vec_i2f(ivec2);
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rect rect_i2f(irect);
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/* Same as vec_i2f() but adds +0.5 at each coordinate. */
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vec2 vec_i2f_center(ivec2);
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/* Functions converting fixed-point shapes to integer. */
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ivec2 vec_f2i(vec2);
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irect rect_f2i(rect);
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/* Dot product. */
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fixed_t vec_dot(vec2, vec2);
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/* Rotate a vector by some constants */
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vec2 vec_rotate_30(vec2);
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vec2 vec_rotate_m30(vec2);
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vec2 vec_rotate_45(vec2);
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vec2 vec_rotate_m45(vec2);
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vec2 vec_rotate_60(vec2);
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vec2 vec_rotate_m60(vec2);
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//---
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// Point operations
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//---
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/* Distance-squared between two points */
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static inline fixed_t dist2(vec2 p1, vec2 p2)
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{
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fixed_t dx = p2.x - p1.x;
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fixed_t dy = p2.y - p1.y;
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return fmul(dx, dx) + fmul(dy, dy);
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}
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/* Unit vector in the specified direction */
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static inline vec2 fdir(int dir)
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{
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return (vec2){
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.x = fix((dir == RIGHT) - (dir == LEFT)),
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.y = fix((dir == DOWN) - (dir == UP)),
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};
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}
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/* Direction closest to specified vector */
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static inline int frdir(vec2 v)
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{
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if(v.x >= abs(v.y)) return RIGHT;
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if(v.x <= -abs(v.y)) return LEFT;
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if(v.y < 0) return UP;
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return DOWN;
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}
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/* Normalize vector */
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static inline vec2 fnormalize(vec2 v)
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{
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fixed_t norm = fmul(v.x, v.x) + fmul(v.y, v.y);
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if(norm == 0) return v;
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norm = fsqrt(norm);
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return (vec2){ fdiv(v.x, norm), fdiv(v.y, norm) };
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}
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//---
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// Rect operations
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//---
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/* Center of rectangle */
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vec2 rect_center(rect r);
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/* Scale a rectangle by the specified factor. */
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rect rect_scale(rect r, fixed_t factor);
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/* Translate a rectangle by the specified point coordinates. */
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rect rect_translate(rect r, vec2 vec);
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/* Draw rectangle on-screen; expects a rectangle in the screen coordinate system. */
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void rect_draw(rect r, int color);
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/* Check whether two rectangles collide */
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bool rect_collide(rect r1, rect r2);
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/* Rotate rectangle from one quad direction to another */
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rect rect_rotate(rect r, int from_dir, int to_dir);
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