Character hair physics implementation

src/gamedata/GUIModule.cpp

@@ -232,22 +232,34 @@ struct GUIListener : public Ogre::RenderTargetListener {
         float width = size.x;
         float height = size.y;
         Ogre::Camera *camera = ECS::get<Camera>().mCamera;
-        // 1. Convert to camera space
+        // 1. Convert to camera space (OGRE camera looks down -Z)
         Ogre::Vector3 eyeSpacePoint =
             camera->getViewMatrix() * worldPoint;
-
-        // 2. Project to clip space
-        Ogre::Vector3 clipSpacePoint =
-            camera->getProjectionMatrix() * eyeSpacePoint;
-        if (clipSpacePoint.z < 0.0f)
+        if (eyeSpacePoint.z >= 0.0f)
             return Ogre::Vector2(-1, -1);
 
-        // 3. Convert from clip space (-1 to 1) to screen space (0 to 1)
-        // Note: Y is usually flipped in API screen coordinates compared to projection
-        float screenX = (clipSpacePoint.x / 2.0f) + 0.5f;
-        float screenY = 1.0f - ((clipSpacePoint.y / 2.0f) + 0.5f);
+        // 2. Project to homogeneous clip space using Vector4 to preserve W
+        Ogre::Vector4 clipSpacePoint =
+            camera->getProjectionMatrix() *
+            Ogre::Vector4(eyeSpacePoint.x, eyeSpacePoint.y,
+                          eyeSpacePoint.z, 1.0f);
+        if (clipSpacePoint.w <= 0.0f)
+            return Ogre::Vector2(-1, -1);
 
-        // 4. Map to actual pixel dimensions
+        // 3. Perspective divide to get NDC [-1, 1]
+        float ndcX = clipSpacePoint.x / clipSpacePoint.w;
+        float ndcY = clipSpacePoint.y / clipSpacePoint.w;
+
+        // 4. Convert NDC to screen space [0, 1], flipping Y for ImGui
+        float screenX = (ndcX * 0.5f) + 0.5f;
+        float screenY = 1.0f - ((ndcY * 0.5f) + 0.5f);
+
+        // 5. Reject if outside viewport bounds
+        if (screenX < 0.0f || screenX > 1.0f ||
+            screenY < 0.0f || screenY > 1.0f)
+            return Ogre::Vector2(-1, -1);
+
+        // 6. Map to actual pixel dimensions
         return Ogre::Vector2(screenX * width, screenY * height);
     }
     void preview(const Ogre::RenderTargetViewportEvent &evt)