[SOLVED] Rectangle light source

mvaligursky · July 22, 2021, 8:03am

also, your lights don’t use shadows … and perhaps clustered lighting is a good candidate to be used.

github.com/playcanvas/engine

Clustered lights - prototype and architecture

playcanvas:master ← playcanvas:mvaligursky-clustered-lights

opened 02:19PM - 19 Mar 21 UTC

mvaligursky

+1435 -84

This is an initial implementation of clustered lighting for local lights without… shadows (omni and spot, with punctual shape - so no area lights). There will be further improvements later to allow these lights to support shadows by rendering them into a shadow atlas. Note that in this implementation, the clustering is done in the World Space instead in more commonly used Camera Space to improve performance, and allow the clustering structure to be used by multiple cameras (for example rendering to texture). It also allows us in the future to avoid rebuilds of this structure if lights don't change). The difference compared to the current local lights implementation is that while current implementation uses all dynamic lights on all objects in the scene, clustered implementation places these lights into a 3d grid structure with specified size, and when a pixel is rendered, lights it needs are fetched from this 3d grid. Thus it works the best if the overlap of lights is not large. Example being a large level with many local lights with small range in various places inside the level. The test case (see screenshot) replicates this. The level is represented by a large cylinder and many other meshes (spheres and cones), which all get lit by the lights. Both omni and spot lights are separated with low density to minimize amount of lights a pixel needs to use. _There is a limitation at the moment in that only diffuse part of lighting is evaluated for clustered lights, and specular is not. This will be addressed in the future._ **Changed API:** constructor of LayerComposition now takes additional parameter, which is a GraphicsDevice. Not passing this parameter is ok for an application using single instance of Application. **New API (all private at this point, as it might be subject to change):** - **WorldClusters.enabled** - enables clustered lighting (disabled by default). Needs to be called before rendering, and cannot be changed after. - **LayerComposition.clusteredLightingCells** - specifies Vec3 with number of cells of the clustering 3d grid - **LayerComposition.clusteredLightingMaxLights** - maximum number of lights a cell can stored. Ideally with small overlap of lights this could be set to a small number, for example 8. **Example of API use:** ``` // enabled clustered lighting. This is a temporary API and will change in the future pc.WorldClusters.enabled = true; // adjust default clusterered lighting parameters to handle many lights: // 1) subdivide space with lights into this many cells: app.scene.layers.clusteredLightingCells = new pc.Vec3(12, 16, 12); // 2) and allow this many lights per cell: app.scene.layers.clusteredLightingMaxLights = 48; ``` **Other changes:** - some refactor to layer composition in how the shadow casters are updated - mostly non functional change, apart from processing each layer only one time (slight optimization) - optimized light management in the layer by using a Set of lights - refactored ShadowCasters into LightCompositionData (mostly rename) **Performance test** (on very old Huawei phone and MacBook Pro). Note that this depends on light overlap, grid size and similar and are only representative or "common" expected scenario. This also confirmed minimal negative impact when zero or small number of lights are used. Also note that API allows to move the cost both ways between CPU and GPU. When you use large number of cells (clusteredLightingCells), CPU update is more costly, but GPU is cheaper as light overlap is more precise. On the other hand it small number of cells is used, CPU update is fast, but GPU needs to use many lights for each pixel. huawei 0 lights - clustered: 0.5ms - normal: 0.5ms PC 0 lights - clustered: 0.2ms - normal: 0.2ms huawei 5 lights - clustered: 2.1ms - normal: 2.8ms huawei 50 lights - clustered: 14.6ms - normal: 36ms PC 50 lights - clustered: 3ms - normal: 32ms **Example** (link valid when released) http://playcanvas.github.io/#graphics/clustered-lighting.html This uses clustered lighting, with a grid size of 12, 16, 12, with the maximum number of lights per cell being 48, and rendering 30 point lights and 16 spot lights. In addition there is one shadowing directional light as well. ![Screen Shot 2021-04-19 at 2 12 13 PM](https://user-images.githubusercontent.com/59932779/115241915-43485400-a119-11eb-88fc-39c70c6a793d.png) References: https://newq.net/publications/more/s2015-many-lights-course