MultiMesh

Inherits: Resource < RefCounted < Object

Provides high-performance drawing of a mesh multiple times using GPU instancing.

Description

MultiMesh provides low-level mesh instancing. Drawing thousands of MeshInstance3D nodes can be slow, since each object is submitted to the GPU then drawn individually.

MultiMesh is much faster as it can draw thousands of instances with a single draw call, resulting in less API overhead.

As a drawback, if the instances are too far away from each other, performance may be reduced as every single instance will always render (they are spatially indexed as one, for the whole object).

Since instances may have any behavior, the AABB used for visibility must be provided by the user.

Note: A MultiMesh is a single object, therefore the same maximum lights per object restriction applies. This means, that once the maximum lights are consumed by one or more instances, the rest of the MultiMesh instances will not receive any lighting.

Note: Blend Shapes will be ignored if used in a MultiMesh.

Tutorials

• Animating thousands of fish with MultiMeshInstance

• Optimization using MultiMeshes

Properties

PackedFloat32Array	buffer	PackedFloat32Array()
PackedColorArray	color_array
PackedColorArray	custom_data_array
int	instance_count	0
Mesh	mesh
PackedVector2Array	transform_2d_array
PackedVector3Array	transform_array
TransformFormat	transform_format	0
bool	use_colors	false
bool	use_custom_data	false
int	visible_instance_count	-1

Methods

AABB	get_aabb ( ) const
Color	get_instance_color ( int instance ) const
Color	get_instance_custom_data ( int instance ) const
Transform3D	get_instance_transform ( int instance ) const
Transform2D	get_instance_transform_2d ( int instance ) const
void	set_instance_color ( int instance, Color color )
void	set_instance_custom_data ( int instance, Color custom_data )
void	set_instance_transform ( int instance, Transform3D transform )
void	set_instance_transform_2d ( int instance, Transform2D transform )

Enumerations

enum TransformFormat:

• TRANSFORM_2D = 0 --- Use this when using 2D transforms.

• TRANSFORM_3D = 1 --- Use this when using 3D transforms.

Property Descriptions

• PackedFloat32Array buffer

Default	PackedFloat32Array()
Setter	set_buffer(value)
Getter	get_buffer()

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• PackedColorArray color_array

See set_instance_color.

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• PackedColorArray custom_data_array

See set_instance_custom_data.

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• int instance_count

Default	0
Setter	set_instance_count(value)
Getter	get_instance_count()

Number of instances that will get drawn. This clears and (re)sizes the buffers. Setting data format or flags afterwards will have no effect.

By default, all instances are drawn but you can limit this with visible_instance_count.

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• Mesh mesh

Setter	set_mesh(value)
Getter	get_mesh()

Mesh resource to be instanced.

The looks of the individual instances can be modified using set_instance_color and set_instance_custom_data.

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• PackedVector2Array transform_2d_array

See set_instance_transform_2d.

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• PackedVector3Array transform_array

See set_instance_transform.

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• TransformFormat transform_format

Default	0
Setter	set_transform_format(value)
Getter	get_transform_format()

Format of transform used to transform mesh, either 2D or 3D.

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• bool use_colors

Default	false
Setter	set_use_colors(value)
Getter	is_using_colors()

If true, the MultiMesh will use color data (see set_instance_color). Can only be set when instance_count is 0 or less. This means that you need to call this method before setting the instance count, or temporarily reset it to 0.

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• bool use_custom_data

Default	false
Setter	set_use_custom_data(value)
Getter	is_using_custom_data()

If true, the MultiMesh will use custom data (see set_instance_custom_data). Can only be set when instance_count is 0 or less. This means that you need to call this method before setting the instance count, or temporarily reset it to 0.

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• int visible_instance_count

Default	-1
Setter	set_visible_instance_count(value)
Getter	get_visible_instance_count()

Limits the number of instances drawn, -1 draws all instances. Changing this does not change the sizes of the buffers.

Method Descriptions

• AABB get_aabb ( ) const

Returns the visibility axis-aligned bounding box in local space. See also VisualInstance3D.get_transformed_aabb.

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• Color get_instance_color ( int instance ) const

Gets a specific instance's color multiplier.

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• Color get_instance_custom_data ( int instance ) const

Returns the custom data that has been set for a specific instance.

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• Transform3D get_instance_transform ( int instance ) const

Returns the Transform3D of a specific instance.

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• Transform2D get_instance_transform_2d ( int instance ) const

Returns the Transform2D of a specific instance.

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• void set_instance_color ( int instance, Color color )

Sets the color of a specific instance by multiplying the mesh's existing vertex colors. This allows for different color tinting per instance.

For the color to take effect, ensure that use_colors is true on the MultiMesh and BaseMaterial3D.vertex_color_use_as_albedo is true on the material. If you intend to set an absolute color instead of tinting, make sure the material's albedo color is set to pure white (Color(1, 1, 1)).

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• void set_instance_custom_data ( int instance, Color custom_data )

Sets custom data for a specific instance. Although Color is used, it is just a container for 4 floating point numbers.

For the custom data to be used, ensure that use_custom_data is true.

This custom instance data has to be manually accessed in your custom shader using INSTANCE_CUSTOM.

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• void set_instance_transform ( int instance, Transform3D transform )

Sets the Transform3D for a specific instance.

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• void set_instance_transform_2d ( int instance, Transform2D transform )

Sets the Transform2D for a specific instance.