I'm trying to do some fancy stuff to mimic the behavior of the mod Repose, where blocks whose collision box is normally a full cube will act as stairs when you're walking up a slope. This makes it so you don't have to jump so much.

 

My code kinda works, but the player gets stuck inside the block. It's almost like the collision boxes are getting modified only some of the time, then changing back to a full cube and trapping the player. Sometimes I can get out for a second but then I get pulled back into the block. I initially suspected some kind of syncing problem, but it behaves the same when I run it on the server only and when I run it on both sides. It does nothing when run on the client only. Do I need to send some kind of packet to the client? Any idea what's going on?

 

Spoiler

    @SubscribeEvent
    public void onCollision(GetCollisionBoxesEvent event)
    {
        if (event.getEntity() != null && event.getEntity() instanceof EntityPlayer)
        {
            List<AxisAlignedBB> collisionBoxesList = event.getCollisionBoxesList();
            Iterator<AxisAlignedBB> collisionBoxesIterator = collisionBoxesList.iterator();
            List<AxisAlignedBB> stairCollisionBoxes = new ArrayList<>();

            while (collisionBoxesIterator.hasNext())
            {
                World world = event.getWorld();

                AxisAlignedBB currentAABB = collisionBoxesIterator.next();
                // Get center of AxisAlignedBB; note that AxisAlignedBB#getCenter is on client side only so won't work here
                double centerX = currentAABB.minX + (currentAABB.maxX - currentAABB.minX) * 0.5D;
                double centerY = currentAABB.minY + (currentAABB.maxY - currentAABB.minY) * 0.5D;
                double centerZ = currentAABB.minZ + (currentAABB.maxZ - currentAABB.minZ) * 0.5D;
                Vec3d vec = new Vec3d(centerX, centerY, centerZ);
                BlockPos pos = new BlockPos(vec.x, vec.y, vec.z);

                IBlockState state = world.getBlockState(pos);
                Block block = state.getBlock();

                    // BLOCKS ACT AS STAIRS

                    // Required block patterns:
                    // A1 = first air block
                    // A2 = second air block
                    // A3 = third air block
                    // XX = solid block
                    // SS = the block in question, which could be turned into a stair
                    // ?? = could be anything

                    // A2 A1 ??    A2 A1 X1
                    // A3 SS X1    A3 SS ??
                    // X2          X2

                    if (block.isNormalCube(state, world, pos) // SS
                            && world.getBlockState(pos.up()).getCollisionBoundingBox(world, pos.up()) == null) // A1
                    {
                        ArrayList<EnumFacing> STAIR_DIRECTIONS = new ArrayList<>();
                        STAIR_DIRECTIONS.addAll(Arrays.asList(EnumFacing.HORIZONTALS));

                        for (EnumFacing direction : EnumFacing.HORIZONTALS)
                        {
                            if (                               world.getBlockState(pos.offset(direction)).getCollisionBoundingBox(world, pos.offset(direction)) == null // A3
                                    && world.getBlockState(pos.offset(direction).up()).getCollisionBoundingBox(world, pos.offset(direction).up()) == null // A2
                                    && world.isBlockNormalCube(pos.offset(direction).down(), false) // X2
                                    && (world.isBlockNormalCube(pos.offset(direction.getOpposite()), false) // X1 or ??
                                    || world.isBlockNormalCube(pos.offset(direction.getOpposite()).up(), false))) // X1 or ??
                            {
                                // Conditions met - remove this direction from list to show we need to remove a stair piece on that side of the block
                                STAIR_DIRECTIONS.remove(direction);
                            }
                        }

                        // If a direction has been removed, it means we need to remove a stair piece from the block
                        // Note that the conditions should make it so the most you can remove is two directions, and they would have to be diagonal to each other
                        if (!STAIR_DIRECTIONS.containsAll(Arrays.asList(EnumFacing.HORIZONTALS)))
                        {
                            collisionBoxesIterator.remove();
                            stairCollisionBoxes.add(AABB_SLAB_BOTTOM.offset(pos));

                            if (STAIR_DIRECTIONS.contains(EnumFacing.NORTH))
                            {
                                if (STAIR_DIRECTIONS.contains(EnumFacing.EAST))
                                {
                                    stairCollisionBoxes.add(NE_CORNER.offset(pos));
                                }
                                if (STAIR_DIRECTIONS.contains(EnumFacing.WEST))
                                {
                                    stairCollisionBoxes.add(NW_CORNER.offset(pos));
                                }
                            }
                            if (STAIR_DIRECTIONS.contains(EnumFacing.SOUTH))
                            {
                                if (STAIR_DIRECTIONS.contains(EnumFacing.EAST))
                                {
                                    stairCollisionBoxes.add(SE_CORNER.offset(pos));
                                }
                                if (STAIR_DIRECTIONS.contains(EnumFacing.WEST))
                                {
                                    stairCollisionBoxes.add(SW_CORNER.offset(pos));
                                }
                            }
                        }
                    }
            }
            collisionBoxesList.addAll(stairCollisionBoxes);
        }
    }

 

 

Edited May 9, 20187 yr by Daeruin
Marking solved.

See:

https://github.com/MinecraftForge/MinecraftForge/blob/1.12.x/src/main/java/net/minecraftforge/client/event/PlayerSPPushOutOfBlocksEvent.java

Can you explain why you think this would help?

 

I was guessing that maybe EntityPlayerSP#pushOutOfBlocks was trying to push the player out of the block, but then the player was falling back in, and was therefore getting stuck. So I tried cancelling PlayerSPPushOutOfBlocksEvent in the same conditions under which I'm modifying the collision boxes. No effect.

So I discovered that players have a stepHeight attribute that does everything I wanted without messing with collision boxes.