MultiMesh

Inherits: Resource < Reference < Object

Provides high-performance mesh instancing.

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.

Tutorials

• Animating thousands of fish with MultiMeshInstance

• Optimization using MultiMeshes

Properties

Methods

Enumerations

enum TransformFormat:

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

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

enum ColorFormat:

• COLOR_NONE = 0 —- Use when you are not using per-instance Colors.

• COLOR_8BIT = 1 —- Compress Color data into 8 bits when passing to shader. This uses less memory and can be faster, but the Color loses precision.

• COLOR_FLOAT = 2 —- The Color passed into set_instance_color will use 4 floats. Use this for highest precision Color.

enum CustomDataFormat:

• CUSTOM_DATA_NONE = 0 —- Use when you are not using per-instance custom data.

• CUSTOM_DATA_8BIT = 1 —- 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.

• CUSTOM_DATA_FLOAT = 2 —- The Color passed into set_instance_custom_data will use 4 floats. Use this for highest precision.

enum PhysicsInterpolationQuality:

• INTERP_QUALITY_FAST = 0 —- Always interpolate using Basis lerping, which can produce warping artifacts in some situations.

• INTERP_QUALITY_HIGH = 1 —- Attempt to interpolate using Basis slerping (spherical linear interpolation) where possible, otherwise fall back to lerping.

Property Descriptions

• ColorFormat color_format

Format of colors in color array that gets passed to shader.

• CustomDataFormat custom_data_format

Format of custom data in custom data array that gets passed to shader.

• int instance_count

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 visible_instance_count.

• Mesh mesh

Mesh to be drawn.

• PhysicsInterpolationQuality physics_interpolation_quality

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.

Note: Fast quality does not equate to low quality. Except in the special cases mentioned above, the quality should be comparable to high quality.

• TransformFormat transform_format

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

• int 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 VisualInstance.get_transformed_aabb.

• Color get_instance_color ( int instance ) const

Gets a specific instance’s color.

• Color get_instance_custom_data ( int instance ) const

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

• Transform get_instance_transform ( int instance ) const

Returns the Transform of a specific instance.

• Transform2D get_instance_transform_2d ( int instance ) const

Returns the Transform2D of a specific instance.

• void reset_instance_physics_interpolation ( int instance )

When using physics interpolation, 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.

• void set_as_bulk_array ( PoolRealArray array )

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, COLOR_8BIT / CUSTOM_DATA_8BIT is stored as 1 float (4 bytes as is) and COLOR_FLOAT / CUSTOM_DATA_FLOAT is stored as 4 floats.

• void set_as_bulk_array_interpolated ( PoolRealArray array_current, PoolRealArray array_previous )

An alternative version of set_as_bulk_array which can be used with physics interpolation. 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 set_as_bulk_array can still be used with interpolation.

• void set_instance_color ( int instance, Color color )

Sets the color of a specific instance by multiplying the mesh’s existing vertex colors.

For the color to take effect, ensure that color_format is non-null on the MultiMesh and SpatialMaterial.vertex_color_use_as_albedo is true on the material.

• 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. The format of the number can change depending on the CustomDataFormat used.

• void set_instance_transform ( int instance, Transform transform )

Sets the Transform for a specific instance.

• void set_instance_transform_2d ( int instance, Transform2D transform )

Sets the Transform2D for a specific instance.