RenderBrewingStand.cpp

bool TileTessellator::tessellateBrewingStandTileInWorld(BrewingStandTile* tile, int x, int y, int z, TileSource* region) {
        Tessellator* tess = this->tessellator_inst;

        // render the center blaze rod
        setRenderBounds(AABB({0.4375, 0.0, 0.4375}, {0.5625, 0.875, 0.5625}));
        tessellateBlockInWorld(tile, {x, y, z});

        // render the 3 blocks on the bottom
        forcedUV = tile->getTextureUVCoordinateSet("brewing_stand_base", 0);
        useForcedUV = true;
        setRenderBounds(AABB({0.5625, 0.0, 0.3125}, {0.9375, 0.125, 0.6875}));
        tessellateBlockInWorld(tile, {x, y, z});
        setRenderBounds(AABB({0.125, 0.0, 0.0625}, {0.5, 0.125, 0.4375}));
        tessellateBlockInWorld(tile, {x, y, z});
        setRenderBounds(AABB({0.125, 0.0, 0.5625}, {0.5, 0.125, 0.9375}));
        tessellateBlockInWorld(tile, {x, y, z});
        useForcedUV = false;
      
        // render the arms that hold the potions
        TextureUVCoordinateSet stand_uv = tile->getTextureUVCoordinateSet("brewing_stand", 0);

        float v0 = stand_uv.minV;
        float v1 = stand_uv.maxV;
        int data = region->getData(x, y, z);

        for (int i = 0; i < 3; ++i) {
            float helper = i * PI * 2.0 / 3.0 + (PI / 2);
            float u0 = stand_uv.getInterpolatedU(8.0F);
            float u1 = stand_uv.maxU;

            if ((data & 1 << i) != 0) {
               u1 = stand_uv.minU;
            }

            float x0 = x + 0.5;
            float x1 = x + 0.5 + sin(helper) * 8.0F / 16.0F;
            float z0 = z + 0.5;
            float z1 = z + 0.5 + cos(helper) * 8.0F / 16.0F;
            tess->vertexUV(x0, (y + 1), z0, u0, v0);
            tess->vertexUV(x0, (y + 0), z0, u0, v1);
            tess->vertexUV(x1, (y + 0), z1, u1, v1);
            tess->vertexUV(x1, (y + 1), z1, u1, v0);
            tess->vertexUV(x1, (y + 1), z1, u1, v0);
            tess->vertexUV(x1, (y + 0), z1, u1, v1);
            tess->vertexUV(x0, (y + 0), z0, u0, v1);
            tess->vertexUV(x0, (y + 1), z0, u0, v0);
        }
        return true;
}

Cool, hmm... anyways I think nobody will make a potions addon now until BL and MCPE updates to the official V.