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.
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.
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.
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>
<methodname="set_instance_color">
<returntype="void"/>
<argumentindex="0"name="instance"type="int"/>
<argumentindex="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.
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.
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].
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.
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.
