Batch group condition

sooyong_Kim · August 9, 2024, 5:38am

Accoding to the documentation about “Batching”, there are ruls for it.

Have the same Batch Group ID
Have the same material
Have the same shader parameters
Be within a bounding box with no side larger than the Max AABB Size
Be in the same layer
Each batch has a maximum vertex count of 65535
For dynamic batches there is a maximum number of movable mesh instances. This hardware dependent but has a maximum of 1024.

Among those condition, there are two conditions I want to know in detail.

“Have the same shader parameters”
What does it mean?

Is it related to the runtime lightmap? or there is something else ?
Does mesh shape matter?
What if a mirrored mesh(entity)? can a mirrored (entity) be a member of a batch group?

What does it mean by “no side larger than the Max AABB”
How can I check if a participant of a batch group exceed the border of max aabb?

mvaligursky · August 19, 2024, 10:37am

Check this code to see what it does:

github.com

playcanvas/engine/blob/c7294d856d951774cd0fce630e51495daaf076a0/src/scene/batching/batch-manager.js#L488-L547


      
          for (let i = 1; i < meshInstancesLeftA.length; i++) {
              const mi = meshInstancesLeftA[i];
          
              // Split by instance number
              if (dynamic && lists[j].length >= maxInstanceCount) {
                  meshInstancesLeftB = meshInstancesLeftB.concat(meshInstancesLeftA.slice(i));
                  break;
              }
          
              // Split by material, layer (legacy), vertex format & index compatibility, shader defines, static source, vert count, overlapping UI
              if ((material !== mi.material) ||
                  (layer !== mi.layer) ||
                  (vertexFormatBatchingHash !== mi.mesh.vertexBuffer.format.batchingHash) ||
                  (indexed !== mi.mesh.primitive[0].indexed) ||
                  (defs !== mi._shaderDefs) ||
                  (vertCount + mi.mesh.vertexBuffer.getNumVertices() > maxNumVertices)) {
                  skipMesh(mi);
                  continue;
              }
              // Split by AABB

This file has been truncated. show original

You could put breakpoints there perhaps to see what is going on.