feat(mat4): add mat4 basic functions

src/math/mat4.c

@@ -0,0 +1,77 @@
+#include "mat4.h"
+#include <string.h>
+
+Mat4_t mat4(const float arr[16]) 
+{
+    Mat4_t mat;
+    memcpy(mat.m, arr, 16*sizeof(float));
+    return mat;
+}
+
+Mat4_t mat4_zro(void) 
+{
+    return (Mat4_t){0};
+}
+
+Mat4_t mat4_ity(void) 
+{
+    return (Mat4_t) {{
+        1, 0, 0, 0, 
+        0, 1, 0, 0,
+        0, 0, 1, 0,
+        0, 0, 0, 1,
+    }};
+}
+
+Mat4_t mat4_add(const Mat4_t* m1, const Mat4_t* m2) 
+{
+    Mat4_t mat;
+    
+    for(int i = 0; i<16; i++) {
+        mat.m[i] = m1->m[i] + m2->m[i];
+    }
+
+    return mat;
+}
+
+Mat4_t mat4_sub(const Mat4_t* m1, const Mat4_t* m2) 
+{
+    Mat4_t mat;
+
+    for(int i = 0; i<16; i++) {
+        mat.m[i] = m1->m[i] - m2->m[i];
+    }
+
+    return mat;
+}
+
+Mat4_t mat4_scl(const Mat4_t* m, float scalar) 
+{
+    Mat4_t mat;
+
+    for(int i = 0; i<16; i++) {
+        mat.m[i] = m->m[i] * scalar;
+    }
+
+    return mat;
+}
+
+Mat4_t mat4_mul(const Mat4_t* m1, const Mat4_t* m2) 
+{
+    Mat4_t mat; 
+
+    for(int i = 0; i<4; i++) {
+        int i3 = i * 3;
+        for (int j = 0; j < 4; j++) {
+            float sum = 0;
+            
+            for (int k = 0; k < 3; k++) {
+                sum += m1->m[i3 + k] * m2->m[k*3 + j];    
+            }
+
+            mat.m[i3 + j] = sum;
+        }
+    }
+
+    return mat;
+}