added help overlay

helper.c

@@ -0,0 +1,21 @@
+#include "helper.h"
+
+Matrix4x4 orthographicProjection2D(float left, float right, float bottom, float top) {
+    Matrix4x4 result;
+
+    // Identity matrix
+    for (int i = 0; i < 4; i++) {
+        for (int j = 0; j < 4; j++) {
+            result.m[i][j] = 0.0f;
+        }
+    }
+
+    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;
+}