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Fix rendering of UP face for waterlogged blocks with translucent sides #3775

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Fix rendering of UP face for waterlogged blocks with translucent sides #3775

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0e8788f
Fix issue where UP face of water in waterlogged block with translucen…
Auth0x78 Jun 26, 2026
d565857
Remove redundant height info by improving the fluid VoxelShape
Auth0x78 Jun 26, 2026
8c24f80
Merge branch 'dev' into fix-culled-fluid-up-face
Auth0x78 Jun 27, 2026
90b65be
Replace manual voxel shape construction with fluid.getShape()
Auth0x78 Jun 29, 2026
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12 changes: 9 additions & 3 deletions ...net/caffeinemc/mods/sodium/client/render/chunk/compile/pipeline/DefaultFluidRenderer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -156,8 +156,8 @@ private boolean isFluidSelfVisible(BlockState selfBlockState, Direction facing,
// only a non-empty self-shape can occlude anything
if (!ShapeComparisonCache.isEmptyShape(selfShape)) {
// a full self-shape occludes everything
if (ShapeComparisonCache.isFullShape(selfShape) && ShapeComparisonCache.isFullShape(fluidShape)) {
return false;
if (ShapeComparisonCache.isFullShape(selfShape)) {
return !ShapeComparisonCache.isFullShape(fluidShape);

@douira douira Jun 26, 2026

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what is the reason for this change? I think this changes the behavior.

@Auth0x78 Auth0x78 Jun 26, 2026 •
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The main reason for this was even when the ShapeComparisonCache.isFullShape(fluidShape) returned FALSE, we fall through to the line return this.occlusionCache.get().lookup(fluidShape, selfShape)

We check in occlusion cache, but the issue is that during first render, the cache is empty (no block data as 1st render), so the lookup() in cache create a new entry and the default creation value is FALSE.
Hence the function returns false and the UP face of the fluid is not visible.

@douira douira Jun 28, 2026

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can we simplify this logic to simply return false when ShapeComparisonCache.isFullShape(selfShape)? The check for ShapeComparisonCache.isFullShape(fluidShape) seems redundant to me when the full self shape already culls everything.

@Auth0x78 Auth0x78 Jun 28, 2026 •
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We have to keep it as in the case of the issue that this resolves there might be the case that the where ShapeComparisonCache.isFullShape(selfShape) returns true, but as the sides of the selfBlock are transparent we need to render the UP face. So in that aspect we need to keep the ShapeComparisonCache.isFullShape(fluidShape) there.

@Auth0x78 Auth0x78 Jun 28, 2026 •
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Either we check the isFullShape(fluidShape) or other way is we can check each side wall of the block and see if its full shape or not, but it will require us to loop over North, South, East and West facing wall surfaces of the current block, which might be less optimal than the current approach although a bit more accurate.

Sorry for the delayed response.

@douira douira Jun 28, 2026

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The culling shape of a block should match what the actual model represents. If the model says it's full, then we should be allowed to rely on that fact to cull anything within it as determined by the culling shape.

@Auth0x78 Auth0x78 Jun 28, 2026 •
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But here var selfShape = selfBlockState.getFaceOcclusionShape(facing); as we can see that the selfShape is a VoxelShape of the surface in the direction of facing and not the entire block's VoxelShape.

}

// perform occlusion of the fluid by the block it's contained in
Expand All @@ -168,7 +168,12 @@ private boolean isFluidSelfVisible(BlockState selfBlockState, Direction facing,
return true;
}

private boolean isFullBlockFluidSelfVisible(BlockState blockState, Direction dir, VoxelShape fluidShape) {
return this.isFluidSelfVisible(blockState, dir, fluidShape);
}

private boolean isFullBlockFluidSelfVisible(BlockState blockState, Direction dir) {
// Assume that is the fluid block is a full sized block
return this.isFluidSelfVisible(blockState, dir, Shapes.block());
}

Expand Down Expand Up @@ -232,7 +237,8 @@ private boolean isSideExposedOffset(BlockAndTintGetter world, BlockState ownBloc
* Calculates the combined visibility of a fluid face based on the neighboring block states and the fluid state.
*/
private boolean isFullBlockFluidVisible(BlockAndTintGetter world, BlockPos pos, Direction dir, BlockState blockState, FluidState fluid) {
return this.isFullBlockFluidSelfVisible(blockState, dir) && this.isFullBlockFluidSideVisible(world, pos, dir, fluid);
VoxelShape fluidShape = fluid.getShape(world, pos);
return isFullBlockFluidSelfVisible(blockState, dir, fluidShape) && this.isFullBlockFluidSideVisible(world, pos, dir, fluid);
}

/**
Expand Down