Get something rendering for hellotriangle

apps/hellotriangle/hellotriangle.cpp

@@ -1,26 +1,40 @@
-#include <oscar/oscar.h>
-
-using namespace osc;
-
-namespace
-{
-    class HelloTriangleScreen final : public IScreen {
-    public:
-         void impl_on_draw() override
-         {
-            Camera camera;
-            graphics::draw(mesh_, identity<Transform>(), material_, camera);
-            camera.render_to_screen();
-         }
-    private:
-        Mesh mesh_ = TorusKnotGeometry{};
-        Material material_ = MeshBasicMaterial{};
-    };
-}
-
-int main(int, char**)
-{
-    osc::App app;
-    app.show<HelloTriangleScreen>();
-    return 0;
-}
+#include <oscar/oscar.h>
+
+using namespace osc;
+
+namespace
+{
+    class HelloTriangleScreen final : public IScreen {
+    public:
+        HelloTriangleScreen()
+        {
+            const Vec3 viewer_pos = {3.0f, 0.0f, 0.0f};
+            camera_.set_position(viewer_pos);
+            camera_.set_direction({-1.0f, 0.0f, 0.0f});
+            const Color color = Color::red();
+            material_.set_ambient_color(0.2f * color);
+            material_.set_diffuse_color(0.5f * color);
+            material_.set_specular_color(0.5f * color);
+            material_.set_viewer_position(viewer_pos);
+        }
+    private:
+         void impl_on_draw() override
+         {
+             const auto secs = App::get().frame_delta_since_startup().count();
+             const auto transform = identity<Transform>().with_rotation(angle_axis(Radians{secs}, Vec3{0.0f, 1.0f, 0.0f}));
+             graphics::draw(mesh_, transform, material_, camera_);
+             camera_.render_to_screen();
+         }
+
+        TorusKnotGeometry mesh_;
+        MeshPhongMaterial material_;
+        Camera camera_;
+    };
+}
+
+int main(int, char**)
+{
+    osc::App app;
+    app.show<HelloTriangleScreen>();
+    return 0;
+}