Initial commit

1 files changed, 83 insertions, 0 deletions

diff --git a/micro/mat4.c b/micro/mat4.c
new file mode 100644
index 0000000..804c204
--- /dev/null
+++ b/micro/mat4.c
@@ -0,0 +1,83 @@
+#include "mat4.h"
+
+#include <string.h>
+#include <math.h>
+
+void mat4_identity(mat4 m)
+{
+        memset(m, 0, sizeof(mat4));
+        m[0][0] = 1;
+        m[1][1] = 1;
+        m[2][2] = 1;
+        m[3][3] = 1;
+}
+
+void mat4_translate(mat4 m, float x, float y)
+{
+        mat4_identity(m);
+        m[0][3] = x;
+        m[1][3] = y;
+}
+
+void mat4_scale(mat4 m, float x, float y)
+{
+        mat4_identity(m);
+        m[0][0] = x;
+        m[1][1] = y;
+}
+
+void mat4_ortho(
+        mat4 m,
+        float l, float r,
+        float t, float b,
+        float n, float f
+)
+{
+        mat4_identity(m);
+
+        m[0][0] = 2.0 / (r - l);
+        m[1][1] = 2.0 / (t - b);
+        m[2][2] = -2.0 / (f - n);
+        m[0][3] = -(r + l) / (r - l);
+        m[1][3] = -(t + b) / (t - b);
+        m[2][3] = -(f + n) / (f - n);
+}
+
+void mat4_perspective(mat4 mat, float yfov, float a, float n, float f)
+{
+        memset(mat, 0, sizeof(mat4));
+
+        // 1000
+        // 0100
+        // 0010
+        // 0001
+        //
+        // 00 01 02 03
+        // 10 11 12 13
+        // 20 21 22 23
+        // 30 31 32 33
+        //
+        // 0 4 8  12
+        // 1 5 9  14
+        // 2 6 10 15
+        // 3 7 11 16
+
+        float cotan = 1.0 / tanf(yfov * DEG2RAD * 0.5);
+        mat[0][0] = cotan / a;
+        mat[1][1] = cotan;
+        mat[2][2] = (f + n) / (n - f);
+        mat[3][2] = -1.0;
+        mat[2][3] = 2.0 * n * f / (n - f);
+}
+
+
+void mat4_mult(mat4 dst, mat4 a, mat4 b)
+{
+        mat4 res;
+        for (int r = 0; r < 4; r++)
+                for (int c = 0; c < 4; c++)
+                        for (int k = 0; k < 4; k++)
+                                res[r][c] = a[r][k] * b[k][c];
+        // memcpy after so that dst can be one of a or b
+        memcpy(dst, res, sizeof(mat4));
+}