Multi-layer rendering support

src/main/kotlin/mods/betterfoliage/model/SpecialRenderModels.kt

@@ -1,7 +1,10 @@
 package mods.betterfoliage.model
 
+import mods.betterfoliage.chunk.BlockCtx
 import mods.betterfoliage.render.pipeline.RenderCtxBase
+import net.minecraft.client.renderer.RenderType
 import net.minecraft.client.renderer.model.IBakedModel
+import net.minecraft.client.renderer.model.WeightedBakedModel
 import net.minecraft.util.WeightedRandom
 import java.util.Random
 
@@ -9,18 +12,46 @@ import java.util.Random
  * Model that makes use of advanced rendering features.
  */
 interface SpecialRenderModel : IBakedModel {
-    fun render(ctx: RenderCtxBase, noDecorations: Boolean = false)
+    /**
+     * Create custom renderdata object. Called once per block. Result is passed to renderLayer().
+     */
+    fun prepare(ctx: BlockCtx, random: Random): Any
+    fun renderLayer(ctx: RenderCtxBase, data: Any, layer: RenderType)
+
+    /**
+     * Get the actual model that will be rendered. Useful for container models (like [WeightedBakedModel]).
+     */
+    fun resolve(random: Random) = this
+}
+
+interface SpecialRenderData {
+    fun canRenderInLayer(layer: RenderType) = false
 }
 
 class WeightedModelWrapper(
     val models: List<WeightedModel>, baseModel: SpecialRenderModel
-): IBakedModel by baseModel, SpecialRenderModel {
+) : IBakedModel by baseModel, SpecialRenderModel {
     class WeightedModel(val model: SpecialRenderModel, weight: Int) : WeightedRandom.Item(weight)
+
     val totalWeight = models.sumBy { it.weight }
 
     fun getModel(random: Random) = WeightedRandom.getWeightedItem(models, random.nextInt(totalWeight))
 
-    override fun render(ctx: RenderCtxBase, noDecorations: Boolean) {
-        getModel(ctx.random).model.render(ctx, noDecorations)
+    override fun resolve(random: Random) = getModel(random).model.resolve(random)
+
+    override fun prepare(ctx: BlockCtx, random: Random) = getModel(random).model.let { actual ->
+        WeightedRenderData(actual, actual.prepare(ctx, random))
+    }
+
+    override fun renderLayer(ctx: RenderCtxBase, data: Any, layer: RenderType) = when (data) {
+        is WeightedRenderData -> data.model.renderLayer(ctx, data.modelRenderData, layer)
+        else -> getModel(ctx.random).model.renderLayer(ctx, data, layer)
     }
 }
+
+data class WeightedRenderData(
+    val model: SpecialRenderModel,
+    val modelRenderData: Any
+) : SpecialRenderData {
+    override fun canRenderInLayer(layer: RenderType) = (modelRenderData as? SpecialRenderData)?.canRenderInLayer(layer) ?: false
+}