Implement raytraced lightmap

src/shape.h

@@ -125,6 +125,8 @@ public:
 class HeightmapPlane : public Shape
 {
 public:
+    std::vector<GLuint> idx;
+    std::vector<vertex_t> vertices;
     bool create(float w, float h, const Image& img, float scale, float height);
     bool create(float w, float h, int div);
 };