Shadow map is also calculated for hidden them

Wagner · June 21, 2024, 9:01pm

My editor uses auxiliary sections that are hidden if they are synchronized with the main model, but if you turn on the light, then a shadow map is also calculated for them, this can be seen by the sharp increase in triangles.

meshInstance.visibleThisFrame = false;
meshInstance.visible = false;

Wagner · June 21, 2024, 11:10pm

After studying the code for some time, I determined what the problem was.

github.com

playcanvas/engine/blob/main/src/scene/renderer/shadow-renderer.js#L152


      
              shadowCam.clearColorBuffer = !hwPcf;
          }
          
          _cullShadowCastersInternal(meshInstances, visible, camera) {
          
              const numInstances = meshInstances.length;
              for (let i = 0; i < numInstances; i++) {
                  const meshInstance = meshInstances[i];
          
                  if (meshInstance.castShadow) {
                      if (!meshInstance.cull || meshInstance._isVisible(camera)) {
                          meshInstance.visibleThisFrame = true;
                          visible.push(meshInstance);
                      }
                  }
              }
          }
          
          /**
           * Culls the list of shadow casters used by the light by the camera, storing visible mesh
           * instances in the specified array.

I make my own decision to show this mesh or not.

Wagner · June 22, 2024, 12:45pm

github.com

playcanvas/engine/blob/main/src/framework/components/render/component.js#L307


      
          if (this._meshInstances) {
          
              const mi = this._meshInstances;
              for (let i = 0; i < mi.length; i++) {
          
                  // if mesh instance was created without a node, assign it here
                  if (!mi[i].node) {
                      mi[i].node = this.entity;
                  }
          
                  mi[i].castShadow = this._castShadows;
                  mi[i].receiveShadow = this._receiveShadows;
                  mi[i].renderStyle = this._renderStyle;
                  mi[i].setLightmapped(this._lightmapped);
                  mi[i].setCustomAabb(this._customAabb);
              }
          
              if (this.enabled && this.entity.enabled) {
                  this.addToLayers();
              }
          }

When adding a meshInstance with a changed castShadow value, it is overwritten in the render component.

mvaligursky · June 24, 2024, 8:04am

I don’t think there’s a way for you to mark mesh instances as visible/invisible each frame, specifically for the shadows. Your best option is to use MeshInstance.visible to mark mesh instances as visible, and this applies to both the main camera and also the shadow camera.