Use p_cam_projection.get_endpoints() to calculate the viewport location

Fixes #104193

In OpenXR the viewport location is not centered on the transform origin

Author: jamie-pate

modules/raycast/raycast_occlusion_cull.cpp

@@ -525,14 +525,14 @@ void RaycastOcclusionCull::buffer_set_size(RID p_buffer, const Vector2i &p_size)
 	buffers[p_buffer].resize(p_size);
 }
 
-Vector2 RaycastOcclusionCull::_jitter_half_extents(const Vector2 &p_half_extents, const Size2i &p_viewport_size) {
+Vector2 RaycastOcclusionCull::_get_jitter(const Vector2 &p_half_extents, const Size2i &p_viewport_size) {
 	if (!_jitter_enabled) {
-		return p_half_extents;
+		return Vector2();
 	}
 
 	// Prevent divide by zero when using NULL viewport.
 	if ((p_viewport_size.x <= 0) || (p_viewport_size.y <= 0)) {
-		return p_half_extents;
+		return Vector2();
 	}
 
 	int32_t frame = Engine::get_singleton()->get_frames_drawn();
@@ -578,7 +578,7 @@ Vector2 RaycastOcclusionCull::_jitter_half_extents(const Vector2 &p_half_extents
 	// False shown can lower percentage that are occluded, and therefore performance.
 	jitter *= 0.66f;
 
-	return p_half_extents + jitter;
+	return jitter;
 }
 
 void RaycastOcclusionCull::buffer_update(RID p_buffer, const Transform3D &p_cam_transform, const Projection &p_cam_projection, bool p_cam_orthogonal) {
@@ -596,8 +596,10 @@ void RaycastOcclusionCull::buffer_update(RID p_buffer, const Transform3D &p_cam_
 	scenario.update();
 
 	Vector2 viewport_half = p_cam_projection.get_viewport_half_extents();
-	Vector2 jitter_viewport_half = _jitter_half_extents(viewport_half, buffer.get_occlusion_buffer_size());
-	Vector3 near_bottom_left = Vector3(-jitter_viewport_half.x, -jitter_viewport_half.y, -p_cam_projection.get_z_near());
+	Vector2 jitter = _get_jitter(viewport_half, buffer.get_occlusion_buffer_size());
+	Vector3 endpoints[8];
+	p_cam_projection.get_endpoints(Transform3D(), endpoints);
+	Vector3 near_bottom_left = Vector3(jitter.x, jitter.y, 0) + endpoints[5];
 
 	buffer.update_camera_rays(p_cam_transform, near_bottom_left, 2 * viewport_half, p_cam_projection.get_z_far(), p_cam_orthogonal);
 

modules/raycast/raycast_occlusion_cull.h

@@ -161,7 +161,7 @@ class RaycastOcclusionCull : public RendererSceneOcclusionCull {
 	bool _jitter_enabled = false;
 
 	void _init_embree();
-	Vector2 _jitter_half_extents(const Vector2 &p_half_extents, const Size2i &p_viewport_size);
+	Vector2 _get_jitter(const Vector2 &p_half_extents, const Size2i &p_viewport_size);
 
 public:
 	virtual bool is_occluder(RID p_rid) override;