restructure zephr

zephr_math.c

@@ -0,0 +1,94 @@
+#include <math.h>
+
+#include "zephr_math.h"
+
+int max(int a, int b) {
+    return a > b ? a : b;
+}
+
+float maxf(float a, float b) {
+    return a > b ? a : b;
+}
+
+float clampf(float value, float min, float max) {
+    if (value < min) {
+        return min;
+    } else if (value > max) {
+        return max;
+    }
+
+    return value;
+}
+
+float to_radians(float degrees) {
+  return degrees * (M_PI / 180.f);
+}
+
+Matrix4x4 orthographic_projection_2d(float left, float right, float bottom, float top) {
+    Matrix4x4 result = identity();
+
+    result.m[0][0] = 2.0f / (right - left);
+    result.m[3][0] = -(right + left) / (right - left);
+    result.m[1][1] = 2.0f / (top - bottom);
+    result.m[3][1] = -(top + bottom) / (top - bottom);
+    result.m[2][2] = -1.0f;
+    result.m[3][3] = 1.0f;
+
+    return result;
+}
+
+Matrix4x4 identity() {
+    Matrix4x4 result = {0};
+
+    result.m[0][0] = 1.0f;
+    result.m[1][1] = 1.0f;
+    result.m[2][2] = 1.0f;
+    result.m[3][3] = 1.0f;
+
+    return result;
+}
+
+void mult_4x4(Matrix4x4 *multiplicant, Matrix4x4 *multiplier) {
+  Matrix4x4 result = identity();
+
+  for (int i = 0; i < 4; i++) {
+    for (int j = 0; j < 4; j++) {
+      result.m[i][j] = 0;
+      for (int k = 0; k < 4; k++) {
+        result.m[i][j] += multiplicant->m[i][k] * multiplier->m[k][j];
+      }
+    }
+  }
+
+  *multiplicant = result;
+}
+
+void apply_scale(Matrix4x4 *matrix, Sizef scale) {
+  Matrix4x4 temp = identity();
+
+  temp.m[0][0] = scale.width;
+  temp.m[1][1] = scale.height;
+
+  mult_4x4(matrix, &temp);
+}
+
+void apply_rotation(Matrix4x4 *model, float angle) {
+  Matrix4x4 temp = identity();
+
+  temp.m[0][0] = cos(angle);
+  temp.m[0][1] = sin(angle);
+  temp.m[1][0] = -sin(angle);
+  temp.m[1][1] = cos(angle);
+
+  mult_4x4(model, &temp);
+}
+
+void apply_translation(Matrix4x4 *matrix, Vec2f pos) {
+  Matrix4x4 temp = identity();
+
+  temp.m[3][0] = pos.x;
+  temp.m[3][1] = pos.y;
+
+  mult_4x4(matrix, &temp);
+}
+