From beaaa8480fb4d8942e052cd202bab4a61dcfd1c0 Mon Sep 17 00:00:00 2001
From: Dennis de vulder <dennisdevulder@gmail.com>
Date: Wed, 29 Jul 2026 15:28:11 +0200
Subject: [PATCH] feat(scene): support whole-model transparency

Port of upstream gpu commit a88ac64d5: fold Model.getTransparency()
into each face's packed alpha via the stock faceTransparency blend,
and force the sorted/alpha capture path when it is non-zero. Without
this, models using the new whole-model fade render fully opaque.

Model transparency is per-renderable and mutable, so it stays out of
the ModelFaceCache key.
---
 .../gpuvulkan/scene/SceneModelEmitter.java    | 32 ++++++++++++++++---
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/main/java/com/gpuvulkan/scene/SceneModelEmitter.java b/src/main/java/com/gpuvulkan/scene/SceneModelEmitter.java
index 7b043ca..747d29b 100644
--- a/src/main/java/com/gpuvulkan/scene/SceneModelEmitter.java
+++ b/src/main/java/com/gpuvulkan/scene/SceneModelEmitter.java
@@ -73,6 +73,7 @@ private static final class ModelArrays
 		byte[] textureFaces;
 		int[] texA, texB, texC;
 		byte[] trans, bias;
+		byte modelTrans;
 		byte overrideHue, overrideSat, overrideLum, overrideAmount;
 		boolean hasOverride;
 
@@ -93,6 +94,7 @@ boolean load(Model m)
 			texB = m.getTexIndices2();
 			texC = m.getTexIndices3();
 			trans = m.getFaceTransparencies();
+			modelTrans = m.getTransparency();
 			bias = m.getFaceBias();
 			overrideAmount = m.getOverrideAmount();
 			overrideHue = m.getOverrideHue();
@@ -199,7 +201,7 @@ private void emitUnsortedFaces(ModelArrays a, int faces,
 			}
 
 			int bias = a.bias != null ? (a.bias[f] & 0xFF) : 0;
-			int trans = a.trans != null ? (a.trans[f] & 0xFF) : 0;
+			int trans = effectiveTransparency(a.modelTrans, a.trans != null ? (a.trans[f] & 0xFF) : 0);
 			// Static sweeps split faces by transparency; 255 is the engine
 			// invisibility sentinel and is dropped from static capture.
 			if (staticFaceFilter == FILTER_OPAQUE && trans != 0) continue;
@@ -282,14 +284,17 @@ void captureModelSorted(Projection proj, Model m, int orient, int worldX, int wo
 		int priorityStart = prioritySort ? sink.currentVertexCount() : -1;
 		int faceCount = m.getFaceCount();
 		byte[] faceTransparencies = m.getFaceTransparencies();
-		if (!prioritySort && faceCount <= OPAQUE_UNSORTED_FACE_THRESHOLD
+		// Whole-model transparency is per-renderable and can change every
+		// frame, so it stays out of the face cache key.
+		boolean modelTransparent = m.getTransparency() != 0;
+		if (!prioritySort && !modelTransparent && faceCount <= OPAQUE_UNSORTED_FACE_THRESHOLD
 			&& ModelFaceCache.countTransparentFaces(faceCount, faceTransparencies) == 0)
 		{
 			captureModelUnsorted(m, orient, worldX, worldY, worldZ);
 			return;
 		}
 		ModelFaceCache.Entry modelInfo = modelFaceCache.info(faceCount, faceTransparencies);
-		boolean needsFaceSort = prioritySort || modelInfo.hasTransparentFaces;
+		boolean needsFaceSort = prioritySort || modelInfo.hasTransparentFaces || modelTransparent;
 		if (!needsFaceSort && modelInfo.faceCount <= OPAQUE_UNSORTED_FACE_THRESHOLD)
 		{
 			captureModelUnsorted(m, orient, worldX, worldY, worldZ);
@@ -420,7 +425,7 @@ private void emitSortedFaces(ModelArrays a, int faces, boolean detailedStats)
 			}
 
 			int bias = a.bias != null ? (a.bias[f] & 0xFF) : 0;
-			int trans = a.trans != null ? (a.trans[f] & 0xFF) : 0;
+			int trans = effectiveTransparency(a.modelTrans, a.trans != null ? (a.trans[f] & 0xFF) : 0);
 			int packedTexLayer = texLayer | (bias << 16) | (trans << 24);
 			boolean noUv = texLayer == 0;
 
@@ -481,6 +486,23 @@ private void emitSortedFaces(ModelArrays a, int faces, boolean detailedStats)
 		emitUvNanos = uvNanos;
 	}
 
+	/** Stock GPU parity: fold whole-model transparency into each face's
+	 *  alpha. -1 is the engine's invisible sentinel; 253+ face values are
+	 *  already sentinels and pass through untouched. */
+	private static int effectiveTransparency(byte modelTransparency, int faceTransparency)
+	{
+		if (modelTransparency == -1)
+		{
+			return 255;
+		}
+		int t = modelTransparency & 0xFF;
+		if (t > 0 && faceTransparency < 253)
+		{
+			return faceTransparency + (((253 - faceTransparency) * t) >> 8);
+		}
+		return faceTransparency;
+	}
+
 	private void recordPriorityRange(int start)
 	{
 		priorityRanges.record(start, sink.currentVertexCount());
@@ -659,7 +681,7 @@ private void emitCulledFaces(ModelArrays a, int faceCount, boolean detailedStats
 			}
 
 			int bias = a.bias != null ? (a.bias[f] & 0xFF) : 0;
-			int trans = a.trans != null ? (a.trans[f] & 0xFF) : 0;
+			int trans = effectiveTransparency(a.modelTrans, a.trans != null ? (a.trans[f] & 0xFF) : 0);
 			int packedTexLayer = texLayer | (bias << 16) | (trans << 24);
 			boolean noUv = texLayer == 0;