How do I prevent large objects from being culled when thay are near the edge of the screen?

Quartz · May 4, 2020, 4:49pm

I’m using large blocks to compose my terrain, but when the camera moves so that any block is near the edge of the screen it disapears.

Naxela · May 4, 2020, 9:07pm

I’m not sure it helps, but if you turn off “Frustum culling” under the Camera > Armory props, does it help? - On the downside it turns off culling in general for your project

Quartz · May 4, 2020, 9:46pm

Yess, that works but I hoped there was a way I could keep frustrum culling to not lose performance, perhaps an adjustable margin or something, or even disabling it only on some objects to use it on terrain.
I imagine armory only takes into account the object’s origin point.

M_Ent8h · May 5, 2020, 11:54am

I imagine armory only takes into account the object’s origin point.

github.com

armory3d/iron/blob/d341d214c0c3fdd0fc60fe76102b5a413b60c319/Sources/iron/object/CameraObject.hx#L169


      
          		// Near plane
          		frustumPlanes[4].setComponents(VP._02, VP._12, VP._22, VP._32);
          		// Far plane
          		frustumPlanes[5].setComponents(VP._03 - VP._02, VP._13 - VP._12, VP._23 - VP._22, VP._33 - VP._32);
          		// Normalize planes
          		for (plane in frustumPlanes) plane.normalize();
          	}
          
          	public static function sphereInFrustum(frustumPlanes: Array<FrustumPlane>, t: Transform, radiusScale = 1.0, offsetX = 0.0, offsetY = 0.0, offsetZ = 0.0): Bool {
          		// Use scale when radius is changing
          		var radius = t.radius * radiusScale;
          		for (plane in frustumPlanes) {
          			sphereCenter.set(t.worldx() + offsetX, t.worldy() + offsetY, t.worldz() + offsetZ);
          			// Outside the frustum
          			if (plane.distanceToSphere(sphereCenter, radius) + radius * 2 < 0) {
          				return false;
          			}
          		}
          		return true;
          	}

The radius of the transform is taken into consideration when culling, so it’s weird… maybe you can plug some trace’s there to spot what is the issue with your mesh… I suspect that probably it has something to do with meshes being flat in some plane, is that the case for your mesh?

Where the radius is computed:

github.com

armory3d/iron/blob/d341d214c0c3fdd0fc60fe76102b5a413b60c319/Sources/iron/object/Transform.hx#L246


      
          	  @param	z Set the z axis rotation in radians.
          	**/
          	public function setRotation(x: kha.FastFloat, y: kha.FastFloat, z: kha.FastFloat) {
          		rot.fromEuler(x, y, z);
          		_eulerX = x;
          		_eulerY = y;
          		_eulerZ = z;
          		dirty = true;
          	}
          
          	function computeRadius() {
          		radius = Math.sqrt(dim.x * dim.x + dim.y * dim.y + dim.z * dim.z);
          	}
          
          	function computeDim() {
          		if (object.raw == null) { computeRadius(); return; }
          		var d = object.raw.dimensions;
          		if (d == null) dim.set(2 * scale.x, 2 * scale.y, 2 * scale.z);
          		else dim.set(d[0] * scale.x, d[1] * scale.y, d[2] * scale.z);
          		computeRadius();
          	}

Mesh culling call:

github.com

armory3d/iron/blob/d341d214c0c3fdd0fc60fe76102b5a413b60c319/Sources/iron/object/MeshObject.hx#L164


      
          			var isShadow = context == "shadowmap";
          			var frustumPlanes = isShadow ? light.frustumPlanes : camera.frustumPlanes;
          
          			if (isShadow && light.data.raw.type != "sun") { // Non-sun light bounds intersect camera frustum
          				light.transform.radius = light.data.raw.far_plane;
          				if (!CameraObject.sphereInFrustum(camera.frustumPlanes, light.transform)) {
          					return setCulled(isShadow, true);
          				}
          			}
          
          			if (!CameraObject.sphereInFrustum(frustumPlanes, transform, radiusScale)) {
          				return setCulled(isShadow, true);
          			}
          		}
          
          		culled = false;
          		return culled;
          	}
          
          	function skipContext(context: String, mat: MaterialData): Bool {
          		if (mat.raw.skip_context != null &&

Quartz · May 5, 2020, 4:05pm

My meshes were basically big cubes with some sides cut open, but it seems that was not the problem, even with an spherical mesh it get’s culled as soon as the center is out of the screen, I realized it only happens to the MeshObjects that I generate using addMeshObject (which I’m no longer using in the current implementation).
While the mesh is displayed at it’s proper size, it’s collision mesh is way too small, and it seems that this is what is taken into account for the culling.