Skip MODE0 fast path for 3D textures

solidpixel · solidpixel · commit fdbd5cf85f7d · 2021-06-21T13:44:38.000+01:00
diff --git a/Source/astcenc_block_sizes.cpp b/Source/astcenc_block_sizes.cpp
@@ -1062,7 +1062,6 @@ static void construct_block_size_descriptor_3d(
 	}
 
 	bsd.decimation_mode_count = decimation_mode_count;
-	bsd.always_decimation_mode_count = 1;
 
 	// Construct the list of block formats
 	unsigned int packed_idx = 0;
@@ -1107,10 +1106,10 @@ static void construct_block_size_descriptor_3d(
 	}
 
 	bsd.block_mode_count = packed_idx;
-	bsd.always_block_mode_count = 1;
 
-	assert(bsd.always_block_mode_count > 0);
-	assert(bsd.always_decimation_mode_count > 0);
+	// These are never used = the MODE0 fast path is skipped for 3D blocks
+	bsd.always_block_mode_count = 0;
+	bsd.always_decimation_mode_count = 0;
 
 	// Determine the texels to use for kmeans clustering.
 	assign_kmeans_texels(bsd);
diff --git a/Source/astcenc_compress_symbolic.cpp b/Source/astcenc_compress_symbolic.cpp
@@ -1431,7 +1431,12 @@ void compress_block(
 
 	static const float errorval_overshoot = 1.0f / ctx.config.tune_refinement_mse_overshoot;
 
-	int start_trial = bsd->texel_count < TUNE_MIN_TEXELS_MODE0_FASTPATH ? 1 : 0;
+	int start_trial = 1;
+	if ((bsd->texel_count < TUNE_MIN_TEXELS_MODE0_FASTPATH) && (bsd->zdim > 1))
+	{
+		start_trial = 0;
+	}
+
 	for (int i = start_trial; i < 2; i++)
 	{
 		TRACE_NODE(node1, "pass");
