I'm porting my roof blocks from Greg's Blocks to 1.8, and I'm having trouble with ambient occlusion. It doesn't seem to be possible to get it to work correctly for faces that are not axis-aligned.
In this screenshot, you can see places where the lower edges of roof blocks are incorrectly shaded, because the rendering system thinks that the cobblestone block below the roof block is casting a shadow on it. This happens because the roof block is not opaque, so it includes the block below in AO calculations rather than the block below and in front. The same thing causes the ridge blocks on top to be shaded too darkly, because they have opaque blocks underneath them.
In my 1.7 rendering code, I dealt with this by only using AO for the exterior axis-aligned faces and not the sloping ones. But the 1.8 rendering system only allows AO to be turned on or off for the whole model, not individual faces, and unless I'm missing something, only allows one BakedModel to be rendered per block.
Anyone have any suggestions?