Implement support for custom blocks

[JustTalDevelops]

Still needs code cleanup.

Below is an example of creating a custom skull block that can be rotated:

type CustomSkull struct {
	empty
	transparent

	Facing cube.Direction
}

func (skull CustomSkull) Name() string {
	return "Custom Skull"
}

func (skull CustomSkull) Category() category.Category {
	return category.Nature()
}

func (skull CustomSkull) Textures() map[string]image.Image {
	return map[string]image.Image{
		"skull": skull.Texture(),
	}
}

func (skull CustomSkull) Texture() image.Image {
	texture, err := os.OpenFile("skull.png", os.O_RDONLY, os.ModePerm)
	if err != nil {
		panic(err)
	}
	defer texture.Close()
	img, err := png.Decode(texture)
	if err != nil {
		panic(err)
	}
	return img
}

func (skull CustomSkull) Geometry() []byte {
	data, err := os.ReadFile("skull.geo.json")
	if err != nil {
		panic(err)
	}
	return data
}

func (skull CustomSkull) UseOnBlock(pos cube.Pos, face cube.Face, _ mgl64.Vec3, w *world.World, user item.User, ctx *item.UseContext) (used bool) {
	pos, _, used = firstReplaceable(w, pos, face, skull)
	if !used {
		return
	}

	skull.Facing = user.Rotation().Direction()
	place(w, pos, skull, user, ctx)
	return placed(ctx)
}

func (skull CustomSkull) EncodeItem() (name string, meta int16) {
	return "dragonfly:skull", 0
}

// EncodeBlock ...
func (skull CustomSkull) EncodeBlock() (string, map[string]any) {
	return "dragonfly:skull", map[string]any{"rotation": int32(skull.Facing)}
}

var skullHash = NextHash()

func (skull CustomSkull) Hash() uint64 {
	return skullHash | (uint64(skull.Facing) << 8)
}

func (skull CustomSkull) Properties() customblock.Properties {
	return customblock.Properties{
		CollisionBox: cube.Box(0.25, 0, 0.25, 0.75, 0.5, 0.75),
		SelectionBox: cube.Box(0.25, 0, 0.25, 0.75, 0.5, 0.75),
		Geometry:     "geometry.skull",
		Textures: map[string]customblock.Material{
			"*": customblock.NewMaterial("skull", customblock.OpaqueRenderMethod()),
		},
	}
}

func (skull CustomSkull) States() map[string][]any {
	return map[string][]any{
		"rotation": {int32(0), int32(1), int32(2), int32(3)},
	}
}

func (skull CustomSkull) Permutations() []customblock.Permutation {
	return []customblock.Permutation{
		{
			Condition: "query.block_state('rotation') == 1",
			Properties: customblock.Properties{
				Rotation: cube.Pos{0, 3, 0},
			},
		},
		{
			Condition: "query.block_state('rotation') == 2",
			Properties: customblock.Properties{
				Rotation: cube.Pos{0, 2, 0},
			},
		},
		{
			Condition: "query.block_state('rotation') == 3",
			Properties: customblock.Properties{
				Rotation: cube.Pos{0, 1, 0},
			},
		},
	}
}

for _, direction := range cube.Directions() {
	world.RegisterBlock(block.CustomSkull{Facing: direction})
}
world.RegisterItem(block.CustomSkull{})
creative.RegisterItem(item.NewStack(block.CustomSkull{}, 1))

// Custom blocks need to be registered before the server is created

srv := conf.New()

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IssueHunt Summary

Referenced issues

This pull request has been submitted to:

• #812: Implement custom blocks

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[JustTalDevelops]

This is now fully functional - feel free to review this. (although, I'm not exactly done with code cleanup yet, will do that ASAP!)

[RoyalMCPE]

It maybe worth exporting firstReplaceable and place so that the end user doesn't have to copy the logic to add vanilla placement to their blocks.

[JustTalDevelops]

Yeah I do agree, I also think other fields such as transparent or empty could be exported, along with newBreakInfo, newSmeltInfo, etc.