<?xml version="1.0" encoding="UTF-8" ?>
<class name="MultiMesh" inherits="Resource" version="3.8">
	<brief_description>
		Provides high-performance mesh instancing.
	</brief_description>
	<description>
		MultiMesh provides low-level mesh instancing. Drawing thousands of [MeshInstance] 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.
	</description>
	<tutorials>
		<link>$DOCS_URL/tutorials/performance/vertex_animation/animating_thousands_of_fish.html</link>
		<link>$DOCS_URL/tutorials/performance/using_multimesh.html</link>
	</tutorials>
	<methods>
		<method name="get_aabb" qualifiers="const">
			<return type="AABB" />
			<description>
				Returns the visibility axis-aligned bounding box in local space. See also [method VisualInstance.get_transformed_aabb].
			</description>
		</method>
		<method name="get_instance_color" qualifiers="const">
			<return type="Color" />
			<argument index="0" name="instance" type="int" />
			<description>
				Gets a specific instance's color.
			</description>
		</method>
		<method name="get_instance_custom_data" qualifiers="const">
			<return type="Color" />
			<argument 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="Transform" />
			<argument index="0" name="instance" type="int" />
			<description>
				Returns the [Transform] of a specific instance.
			</description>
		</method>
		<method name="get_instance_transform_2d" qualifiers="const">
			<return type="Transform2D" />
			<argument 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" />
			<argument 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="set_as_bulk_array">
			<return type="void" />
			<argument index="0" name="array" type="PoolRealArray" />
			<description>
				Sets all data related to the instances in one go. This is especially useful when loading the data from disk or preparing the data from GDNative.
				All data is packed in one large float array. An array may look like this: Transform for instance 1, color data for instance 1, custom data for instance 1, transform for instance 2, color data for instance 2, etc...
				[Transform] is stored as 12 floats, [Transform2D] is stored as 8 floats, [code]COLOR_8BIT[/code] / [code]CUSTOM_DATA_8BIT[/code] is stored as 1 float (4 bytes as is) and [code]COLOR_FLOAT[/code] / [code]CUSTOM_DATA_FLOAT[/code] is stored as 4 floats.
			</description>
		</method>
		<method name="set_as_bulk_array_interpolated">
			<return type="void" />
			<argument index="0" name="array_current" type="PoolRealArray" />
			<argument index="1" name="array_previous" type="PoolRealArray" />
			<description>
				An alternative version of [method MultiMesh.set_as_bulk_array] 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 [method MultiMesh.set_as_bulk_array] can still be used with interpolation.
			</description>
		</method>
		<method name="set_instance_color">
			<return type="void" />
			<argument index="0" name="instance" type="int" />
			<argument index="1" name="color" type="Color" />
			<description>
				Sets the color of a specific instance by [i]multiplying[/i] the mesh's existing vertex colors.
				For the color to take effect, ensure that [member color_format] is non-[code]null[/code] on the [MultiMesh] and [member SpatialMaterial.vertex_color_use_as_albedo] is [code]true[/code] on the material.
			</description>
		</method>
		<method name="set_instance_custom_data">
			<return type="void" />
			<argument index="0" name="instance" type="int" />
			<argument index="1" name="custom_data" type="Color" />
			<description>
				Sets custom data for a specific instance. Although [Color] is used, it is just a container for 4 floating point numbers. The format of the number can change depending on the [enum CustomDataFormat] used.
			</description>
		</method>
		<method name="set_instance_transform">
			<return type="void" />
			<argument index="0" name="instance" type="int" />
			<argument index="1" name="transform" type="Transform" />
			<description>
				Sets the [Transform] for a specific instance.
			</description>
		</method>
		<method name="set_instance_transform_2d">
			<return type="void" />
			<argument index="0" name="instance" type="int" />
			<argument index="1" name="transform" type="Transform2D" />
			<description>
				Sets the [Transform2D] for a specific instance.
			</description>
		</method>
	</methods>
	<members>
		<member name="color_format" type="int" setter="set_color_format" getter="get_color_format" enum="MultiMesh.ColorFormat" default="0">
			Format of colors in color array that gets passed to shader.
		</member>
		<member name="custom_data_format" type="int" setter="set_custom_data_format" getter="get_custom_data_format" enum="MultiMesh.CustomDataFormat" default="0">
			Format of custom data in custom data array that gets passed to shader.
		</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. 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 to be drawn.
		</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_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="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="COLOR_NONE" value="0" enum="ColorFormat">
			Use when you are not using per-instance [Color]s.
		</constant>
		<constant name="COLOR_8BIT" value="1" enum="ColorFormat">
			Compress [Color] data into 8 bits when passing to shader. This uses less memory and can be faster, but the [Color] loses precision.
		</constant>
		<constant name="COLOR_FLOAT" value="2" enum="ColorFormat">
			The [Color] passed into [method set_instance_color] will use 4 floats. Use this for highest precision [Color].
		</constant>
		<constant name="CUSTOM_DATA_NONE" value="0" enum="CustomDataFormat">
			Use when you are not using per-instance custom data.
		</constant>
		<constant name="CUSTOM_DATA_8BIT" value="1" enum="CustomDataFormat">
			Compress custom_data into 8 bits when passing to shader. This uses less memory and can be faster, but loses precision and range. Floats packed into 8 bits can only represent values between 0 and 1, numbers outside that range will be clamped.
		</constant>
		<constant name="CUSTOM_DATA_FLOAT" value="2" enum="CustomDataFormat">
			The [Color] passed into [method set_instance_custom_data] will use 4 floats. Use this for highest precision.
		</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>
