132 lines
3.4 KiB
C
132 lines
3.4 KiB
C
#include <math.h>
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#include "matrix.h"
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mat4_t mat4_identity(void) {
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// | 1 0 0 0 |
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// | 0 1 0 0 |
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// | 0 0 1 0 |
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// | 0 0 0 1 |
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mat4_t m = {{
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{ 1, 0, 0, 0 },
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{ 0, 1, 0, 0 },
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{ 0, 0, 1, 0 },
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{ 0, 0, 0, 1 }
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}};
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return m;
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}
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mat4_t mat4_make_scale(float sx, float sy, float sz) {
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// | sx 0 0 0 |
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// | 0 sy 0 0 |
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// | 0 0 sz 0 |
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// | 0 0 0 1 |
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mat4_t m = mat4_identity();
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m.m[0][0] = sx;
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m.m[1][1] = sy;
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m.m[2][2] = sz;
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return m;
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}
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mat4_t mat4_make_translation(float tx, float ty, float tz) {
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// | 1 0 0 tx |
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// | 0 1 0 ty |
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// | 0 0 1 tz |
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// | 0 0 0 1 |
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mat4_t m = mat4_identity();
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m.m[0][3] = tx;
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m.m[1][3] = ty;
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m.m[2][3] = tz;
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return m;
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}
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mat4_t mat4_make_rotation_x(float angle) {
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float c = cos(angle);
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float s = sin(angle);
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// | 1 0 0 0 |
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// | 0 c -s 0 |
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// | 0 s c 0 |
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// | 0 0 0 1 |
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mat4_t m = mat4_identity();
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m.m[1][1] = c;
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m.m[1][2] = -s;
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m.m[2][1] = s;
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m.m[2][2] = c;
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return m;
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}
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mat4_t mat4_make_rotation_y(float angle) {
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float c = cos(angle);
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float s = sin(angle);
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// | c 0 s 0 |
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// | 0 1 0 0 |
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// | -s 0 c 0 |
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// | 0 0 0 1 |
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mat4_t m = mat4_identity();
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m.m[0][0] = c;
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m.m[0][2] = s;
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m.m[2][0] = -s;
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m.m[2][2] = c;
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return m;
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}
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mat4_t mat4_make_rotation_z(float angle) {
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float c = cos(angle);
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float s = sin(angle);
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// | c -s 0 0 |
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// | s c 0 0 |
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// | 0 0 1 0 |
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// | 0 0 0 1 |
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mat4_t m = mat4_identity();
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m.m[0][0] = c;
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m.m[0][1] = -s;
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m.m[1][0] = s;
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m.m[1][1] = c;
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return m;
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}
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vec4_t mat4_mul_vec4(mat4_t m, vec4_t v) {
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vec4_t result;
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result.x = m.m[0][0] * v.x + m.m[0][1] * v.y + m.m[0][2] * v.z + m.m[0][3] * v.w;
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result.y = m.m[1][0] * v.x + m.m[1][1] * v.y + m.m[1][2] * v.z + m.m[1][3] * v.w;
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result.z = m.m[2][0] * v.x + m.m[2][1] * v.y + m.m[2][2] * v.z + m.m[2][3] * v.w;
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result.w = m.m[3][0] * v.x + m.m[3][1] * v.y + m.m[3][2] * v.z + m.m[3][3] * v.w;
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return result;
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}
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mat4_t mat4_mul_mat4(mat4_t a, mat4_t b) {
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mat4_t m;
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for (int i = 0; i < 4; i++) {
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for (int j = 0; j < 4; j++) {
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m.m[i][j] = a.m[i][0] * b.m[0][j] + a.m[i][1] * b.m[1][j] + a.m[i][2] * b.m[2][j] + a.m[i][3] * b.m[3][j];
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}
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}
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return m;
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}
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mat4_t mat4_make_perspective(float fov, float aspect, float znear, float zfar) {
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// | (h/w)*1/tan(fov/2) 0 0 0 |
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// | 0 1/tan(fov/2) 0 0 |
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// | 0 0 zf/(zf-zn) (-zf*zn)/(zf-zn) |
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// | 0 0 1 0 |
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mat4_t m = {{{ 0 }}};
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m.m[0][0] = aspect * (1 / tan(fov / 2));
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m.m[1][1] = 1 / tan(fov / 2);
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m.m[2][2] = zfar / (zfar - znear);
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m.m[2][3] = (-zfar * znear) / (zfar - znear);
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m.m[3][2] = 1.0;
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return m;
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}
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vec4_t mat4_mul_vec4_project(mat4_t mat_proj, vec4_t v) {
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// multiply the projection matrix by our original vector
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vec4_t result = mat4_mul_vec4(mat_proj, v);
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// perform perspective divide with original z-value that is now stored in w
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if (result.w != 0.0) {
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result.x /= result.w;
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result.y /= result.w;
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result.z /= result.w;
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}
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return result;
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}
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