<?xml version="1.0" encoding="UTF-8" ?>
<class name="MultiMesh" inherits="Resource" keywords="batch" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
	<brief_description>
		Provides high-performance drawing of a mesh multiple times using GPU instancing.
	</brief_description>
	<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.
		[b]Note:[/b] 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 [b]not[/b] receive any lighting.
		[b]Note:[/b] Blend Shapes will be ignored if used in a MultiMesh.
	</description>
	<tutorials>
		<link title="Using MultiMeshInstance">$DOCS_URL/tutorials/3d/using_multi_mesh_instance.html</link>
		<link title="Optimization using MultiMeshes">$DOCS_URL/tutorials/performance/using_multimesh.html</link>
		<link title="Animating thousands of fish with MultiMeshInstance">$DOCS_URL/tutorials/performance/vertex_animation/animating_thousands_of_fish.html</link>
	</tutorials>
	<methods>
		<method name="get_aabb" qualifiers="const">
			<return type="AABB" />
			<description>
				Returns the visibility axis-aligned bounding box in local space.
			</description>
		</method>
		<method name="get_instance_color" qualifiers="const">
			<return type="Color" />
			<param index="0" name="instance" type="int" />
			<description>
				Gets a specific instance's color multiplier.
			</description>
		</method>
		<method name="get_instance_custom_data" qualifiers="const">
			<return type="Color" />
			<param index="0" name="instance" type="int" />
			<description>
				Returns the custom data that has been set for a specific instance.
			</description>
		</method>
		<method name="get_instance_transform" qualifiers="const">
			<return type="Transform3D" />
			<param index="0" name="instance" type="int" />
			<description>
				Returns the [Transform3D] of a specific instance.
			</description>
		</method>
		<method name="get_instance_transform_2d" qualifiers="const">
			<return type="Transform2D" />
			<param index="0" name="instance" type="int" />
			<description>
				Returns the [Transform2D] of a specific instance.
			</description>
		</method>
		<method name="reset_instance_physics_interpolation">
			<return type="void" />
			<param index="0" name="instance" type="int" />
			<description>
				When using [i]physics interpolation[/i], this function allows you to prevent interpolation on an instance in the current physics tick.
				This allows you to move instances instantaneously, and should usually be used when initially placing an instance such as a bullet to prevent graphical glitches.
			</description>
		</method>
		<method name="reset_instances_physics_interpolation">
			<return type="void" />
			<description>
				When using [i]physics interpolation[/i], this function allows you to prevent interpolation for all instances in the current physics tick.
				This allows you to move all instances instantaneously, and should usually be used when initially placing instances to prevent graphical glitches.
			</description>
		</method>
		<method name="set_buffer_interpolated">
			<return type="void" />
			<param index="0" name="buffer_curr" type="PackedFloat32Array" />
			<param index="1" name="buffer_prev" type="PackedFloat32Array" />
			<description>
				An alternative to setting the [member buffer] property, which can be used with [i]physics interpolation[/i]. This method takes two arrays, and can set the data for the current and previous tick in one go. The renderer will automatically interpolate the data at each frame.
				This is useful for situations where the order of instances may change from physics tick to tick, such as particle systems.
				When the order of instances is coherent, the simpler alternative of setting [member buffer] can still be used with interpolation.
			</description>
		</method>
		<method name="set_instance_color">
			<return type="void" />
			<param index="0" name="instance" type="int" />
			<param index="1" name="color" type="Color" />
			<description>
				Sets the color of a specific instance by [i]multiplying[/i] the mesh's existing vertex colors. This allows for different color tinting per instance.
				[b]Note:[/b] Each component is stored in 32 bits in the Forward+ and Mobile rendering methods, but is packed into 16 bits in the Compatibility rendering method.
				For the color to take effect, ensure that [member use_colors] is [code]true[/code] on the [MultiMesh] and [member BaseMaterial3D.vertex_color_use_as_albedo] is [code]true[/code] 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 ([code]Color(1, 1, 1)[/code]).
			</description>
		</method>
		<method name="set_instance_custom_data">
			<return type="void" />
			<param index="0" name="instance" type="int" />
			<param index="1" name="custom_data" type="Color" />
			<description>
				Sets custom data for a specific instance. [param custom_data] is a [Color] type only to contain 4 floating-point numbers.
				[b]Note:[/b] Each number is stored in 32 bits in the Forward+ and Mobile rendering methods, but is packed into 16 bits in the Compatibility rendering method.
				For the custom data to be used, ensure that [member use_custom_data] is [code]true[/code].
				This custom instance data has to be manually accessed in your custom shader using [code]INSTANCE_CUSTOM[/code].
			</description>
		</method>
		<method name="set_instance_transform">
			<return type="void" />
			<param index="0" name="instance" type="int" />
			<param index="1" name="transform" type="Transform3D" />
			<description>
				Sets the [Transform3D] for a specific instance.
			</description>
		</method>
		<method name="set_instance_transform_2d">
			<return type="void" />
			<param index="0" name="instance" type="int" />
			<param index="1" name="transform" type="Transform2D" />
			<description>
				Sets the [Transform2D] for a specific instance.
			</description>
		</method>
	</methods>
	<members>
		<member name="buffer" type="PackedFloat32Array" setter="set_buffer" getter="get_buffer" default="PackedFloat32Array()">
		</member>
		<member name="color_array" type="PackedColorArray" setter="_set_color_array" getter="_get_color_array" deprecated="Accessing this property is very slow. Use [method set_instance_color] and [method get_instance_color] instead.">
			Array containing each [Color] used by all instances of this mesh.
		</member>
		<member name="custom_aabb" type="AABB" setter="set_custom_aabb" getter="get_custom_aabb" default="AABB(0, 0, 0, 0, 0, 0)">
			Custom AABB for this MultiMesh resource. Setting this manually prevents costly runtime AABB recalculations.
		</member>
		<member name="custom_data_array" type="PackedColorArray" setter="_set_custom_data_array" getter="_get_custom_data_array" deprecated="Accessing this property is very slow. Use [method set_instance_custom_data] and [method get_instance_custom_data] instead.">
			Array containing each custom data value used by all instances of this mesh, as a [PackedColorArray].
		</member>
		<member name="instance_count" type="int" setter="set_instance_count" getter="get_instance_count" default="0">
			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 [member visible_instance_count].
		</member>
		<member name="mesh" type="Mesh" setter="set_mesh" getter="get_mesh">
			[Mesh] resource to be instanced.
			The looks of the individual instances can be modified using [method set_instance_color] and [method set_instance_custom_data].
		</member>
		<member name="physics_interpolation_quality" type="int" setter="set_physics_interpolation_quality" getter="get_physics_interpolation_quality" enum="MultiMesh.PhysicsInterpolationQuality" default="0">
			Choose whether to use an interpolation method that favors speed or quality.
			When using low physics tick rates (typically below 20) or high rates of object rotation, you may get better results from the high quality setting.
			[b]Note:[/b] Fast quality does not equate to low quality. Except in the special cases mentioned above, the quality should be comparable to high quality.
		</member>
		<member name="transform_2d_array" type="PackedVector2Array" setter="_set_transform_2d_array" getter="_get_transform_2d_array" deprecated="Accessing this property is very slow. Use [method set_instance_transform_2d] and [method get_instance_transform_2d] instead.">
			Array containing each [Transform2D] value used by all instances of this mesh, as a [PackedVector2Array]. Each transform is divided into 3 [Vector2] values corresponding to the transforms' [code]x[/code], [code]y[/code], and [code]origin[/code].
		</member>
		<member name="transform_array" type="PackedVector3Array" setter="_set_transform_array" getter="_get_transform_array" deprecated="Accessing this property is very slow. Use [method set_instance_transform] and [method get_instance_transform] instead.">
			Array containing each [Transform3D] value used by all instances of this mesh, as a [PackedVector3Array]. Each transform is divided into 4 [Vector3] values corresponding to the transforms' [code]x[/code], [code]y[/code], [code]z[/code], and [code]origin[/code].
		</member>
		<member name="transform_format" type="int" setter="set_transform_format" getter="get_transform_format" enum="MultiMesh.TransformFormat" default="0">
			Format of transform used to transform mesh, either 2D or 3D.
		</member>
		<member name="use_colors" type="bool" setter="set_use_colors" getter="is_using_colors" default="false">
			If [code]true[/code], the [MultiMesh] will use color data (see [method set_instance_color]). Can only be set when [member instance_count] is [code]0[/code] or less. This means that you need to call this method before setting the instance count, or temporarily reset it to [code]0[/code].
		</member>
		<member name="use_custom_data" type="bool" setter="set_use_custom_data" getter="is_using_custom_data" default="false">
			If [code]true[/code], the [MultiMesh] will use custom data (see [method set_instance_custom_data]). Can only be set when [member instance_count] is [code]0[/code] or less. This means that you need to call this method before setting the instance count, or temporarily reset it to [code]0[/code].
		</member>
		<member name="visible_instance_count" type="int" setter="set_visible_instance_count" getter="get_visible_instance_count" default="-1">
			Limits the number of instances drawn, -1 draws all instances. Changing this does not change the sizes of the buffers.
		</member>
	</members>
	<constants>
		<constant name="TRANSFORM_2D" value="0" enum="TransformFormat">
			Use this when using 2D transforms.
		</constant>
		<constant name="TRANSFORM_3D" value="1" enum="TransformFormat">
			Use this when using 3D transforms.
		</constant>
		<constant name="INTERP_QUALITY_FAST" value="0" enum="PhysicsInterpolationQuality">
			Always interpolate using Basis lerping, which can produce warping artifacts in some situations.
		</constant>
		<constant name="INTERP_QUALITY_HIGH" value="1" enum="PhysicsInterpolationQuality">
			Attempt to interpolate using Basis slerping (spherical linear interpolation) where possible, otherwise fall back to lerping.
		</constant>
	</constants>
</class>
