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#ifndef MATH3D_H
#define MATH3D_H
#include "math.h"
static inline void mat_id(float mat[4][4])
{
for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
mat[i][j] = i == j ? 1.0 : 0.0;
}
static inline void mat_translate(float mat[4][4], float vec[3])
{
mat_id(mat);
for (int i = 0; i < 3; i++)
mat[3][i] = vec[i];
}
static inline void mat_scale(float mat[4][4], float vec[3])
{
mat_id(mat);
for (int i = 0; i < 3; i++)
mat[i][i] = vec[i];
}
static inline void mat_rot_x(float mat[4][4], float a)
{
mat_id(mat);
mat[1][1] = cos(a); mat[2][1] = -sin(a);
mat[1][2] = sin(a); mat[2][2] = cos(a);
}
static inline void mat_rot_y(float mat[4][4], float a)
{
mat_id(mat);
mat[0][0] = cos(a); mat[2][0] = sin(a);
mat[0][2] = -sin(a); mat[2][2] = cos(a);
}
static inline void mat_rot_z(float mat[4][4], float a)
{
mat_id(mat);
mat[0][0] = cos(a); mat[1][0] = -sin(a);
mat[0][1] = sin(a); mat[1][1] = cos(a);
}
static inline void mat_copy(float dst[4][4], float src[4][4])
{
for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++)
dst[i][j] = src[i][j];
}
static inline void mat_mul(float a[4][4], float b[4][4])
{
float out[4][4];
for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++) {
out[i][j] = 0;
for (int k = 0; k < 4; k++)
out[i][j] += a[k][j] * b[i][k];
}
mat_copy(a, out);
}
static inline void vec_copy(float dst[4], float src[4])
{
for (int i = 0; i < 4; i++)
dst[i] = src[i];
}
static inline void mat_mul_vec(float mat[4][4], float vec[4])
{
float out[4];
for (int j = 0; j < 4; j++) {
out[j] = 0;
for (int k = 0; k < 4; k++)
out[j] += mat[k][j] * vec[k];
}
vec_copy(vec, out);
}
static inline void mat_perspective(float mat[4][4], float fov, float aspect, float near, float far)
{
float a = 1.0 / tan(fov / 2.0);
mat_scale(mat, (float []) { a/aspect, a, -(far + near) / (far - near) });
mat[2][3] = -1.0;
mat[3][2] = -2.0 * far * near / (far - near);
mat[3][3] = 0.0;
}
static inline float tri_area(float a[2], float b[2], float c[2])
{
return (b[0] - a[0])*(c[1] - a[1]) - (b[1] - a[1])*(c[0] - a[0]);
}
#endif
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