init: first commit - rendering triangle

polygon.hpp

@@ -0,0 +1,29 @@
+#ifndef POLYGON_H
+#define POLYGON_H
+
+#include "fastmath.hpp"
+
+struct polygon {
+
+    const vec3 points[3];
+
+    polygon(const vec3 &v1, const vec3 &v2, const vec3 &v3)
+        : points{v1, v2, v3} {}
+
+    bool contains(const vec3 &p) {
+        for (int i = 0; i < 3; i++) {
+            int n = (i + 1) % 3;
+
+            vec3 d = points[n] - points[i];
+            d = vec3(d.y, -d.x, d.z);
+
+            vec3 s = p - points[n];
+
+            if (s * d < decimal(0.0))
+                return false;
+        }
+        return true;
+    }
+};
+
+#endif