[Native] MultiRenderTarget, reverse-Z clear, applyStates, OIT alpha modes

packages/dev/core/src/Engines/Native/nativeHelpers.ts

@@ -1,5 +1,6 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 import { ErrorCodes, RuntimeError } from "core/Misc/error";
+import { Logger } from "core/Misc/logger";
 import { Constants } from "../constants";
 import { type INative } from "./nativeInterfaces";
 import { VertexBuffer } from "core/Buffers/buffer.pure";
@@ -299,6 +300,18 @@ export function getNativeStencilDepthPass(opPass: number): number {
     }
 }
 
+const _warnedUnsupportedAlphaModes = new Set<number>();
+
+// Some alpha modes were introduced alongside newer Babylon Native features. When running against an older
+// native binary the corresponding _native.Engine constant is undefined; warn once and fall back to ALPHA_ONEONE.
+function _getFallbackAlphaMode(mode: number, unsupportedName: string): number {
+    if (!_warnedUnsupportedAlphaModes.has(mode)) {
+        _warnedUnsupportedAlphaModes.add(mode);
+        Logger.Warn(`Alpha mode ${unsupportedName} is not supported by this version of Babylon Native; falling back to ALPHA_ONEONE.`);
+    }
+    return _native.Engine.ALPHA_ONEONE;
+}
+
 export function getNativeAlphaMode(mode: number): number {
     switch (mode) {
         case Constants.ALPHA_DISABLE:
@@ -315,6 +328,10 @@ export function getNativeAlphaMode(mode: number): number {
             return _native.Engine.ALPHA_MAXIMIZED;
         case Constants.ALPHA_ONEONE:
             return _native.Engine.ALPHA_ONEONE;
+        case Constants.ALPHA_ONEONE_ONEONE:
+            return _native.Engine.ALPHA_ONEONE_ONEONE ?? _getFallbackAlphaMode(mode, "ALPHA_ONEONE_ONEONE");
+        case Constants.ALPHA_LAYER_ACCUMULATE:
+            return _native.Engine.ALPHA_LAYER_ACCUMULATE ?? _getFallbackAlphaMode(mode, "ALPHA_LAYER_ACCUMULATE");
         case Constants.ALPHA_PREMULTIPLIED:
             return _native.Engine.ALPHA_PREMULTIPLIED;
         case Constants.ALPHA_PREMULTIPLIED_PORTERDUFF:

packages/dev/core/src/Engines/Native/nativeInterfaces.ts

@@ -125,6 +125,14 @@ export interface INativeEngine {
         samples: number,
         layer?: number
     ): NativeFramebuffer;
+    createMultiFrameBuffer?(
+        textures: NativeTexture[],
+        width: number,
+        height: number,
+        generateStencilBuffer: boolean,
+        generateDepthBuffer: boolean,
+        samples: number
+    ): NativeFramebuffer;
 
     getRenderWidth(): number;
     getRenderHeight(): number;
@@ -293,6 +301,8 @@ interface INativeEngineConstructor {
     readonly ALPHA_MULTIPLY: number;
     readonly ALPHA_MAXIMIZED: number;
     readonly ALPHA_ONEONE: number;
+    readonly ALPHA_ONEONE_ONEONE?: number;
+    readonly ALPHA_LAYER_ACCUMULATE?: number;
     readonly ALPHA_PREMULTIPLIED: number;
     readonly ALPHA_PREMULTIPLIED_PORTERDUFF: number;
     readonly ALPHA_INTERPOLATE: number;

packages/dev/core/src/Engines/Native/nativeRenderTargetWrapper.ts

@@ -1,4 +1,5 @@
 import { type Nullable } from "../../types";
+import { type InternalTexture } from "../../Materials/Textures/internalTexture";
 import { type TextureSize } from "../../Materials/Textures/textureCreationOptions";
 import { RenderTargetWrapper } from "../renderTargetWrapper";
 import { type NativeFramebuffer } from "./nativeInterfaces";
@@ -57,6 +58,19 @@ export class NativeRenderTargetWrapper extends RenderTargetWrapper {
         this._engine = engine;
     }
 
+    public override setTexture(texture: InternalTexture, index: number = 0, disposePrevious: boolean = true): void {
+        const previous = this.textures?.[index];
+        super.setTexture(texture, index, disposePrevious);
+
+        // bgfx binds a fixed attachment set when a framebuffer is created and cannot re-point an individual
+        // attachment the way GL's framebufferTexture2D can. When a multi render target attachment is swapped
+        // after creation (e.g. the OIT depth-peeling renderer replaces every attachment via
+        // MultiRenderTarget.setInternalTexture), recreate the whole framebuffer from the new attachment set.
+        if (this.isMulti && this.textures?.[index] !== previous) {
+            this._engine._createMultiRenderTargetFramebuffer(this);
+        }
+    }
+
     public override dispose(disposeOnlyFramebuffers = false): void {
         if (this.__framebuffers) {
             // Releases all six per-face framebuffers (face 0 is aliased by __framebuffer, so