Billboard - PopcornFX

Overview

This is the most used particle renderer. It displays the particles as textured sprites.
It has various options to control how the particles are displayed, rotated, scaled, which texture is mapped on them, etc…
This renderer is supported in all of our public engine integrations.
Billboards are displayed onscreen based on an input position, size, color and additional per particle or static properties.

Default Materials:

Default_Billboard: Regular transparent billboard (additive, alpha-blended, or premultiplied-alpha)
Opaque_Billboard: Opaque billboard, can use alpha-testing for cutouts
Distortion_Billboard: Billboard drawing in the distortion pass, useful for heat-shimmering effects

Geometry generation

Billboard renderers support various billboarding modes (alignments):

Screen aligned

4 vertices / 2 triangles per particle

A screen-aligned billboard has its plane parallel to the screen plane.

Looking around and rotating the view camera changes the billboard orientation, while only changing the camera position doesn’t.

Viewpos aligned

4 vertices / 2 triangles per particle

A viewpos-aligned quad has its plane normal pointing towards the camera position.

Unlike screen-aligned quads, looking around does not change the billboard geometry.

Axis aligned

4 vertices / 2 triangles per particle

This billboard mode stretches the billboard geometry along the user-provided axis.

The billboard rotates around the specified axis to try facing the camera

Axis aligned spheroid

4 vertices / 2 triangles per particle

Unlike the AxisAligned billboarding mode, this one doesn’t suffer from the grazing-angle problem, where the particle appears to vanish when the billboarding axis becomes near-perpendicular with the screen plane.

Instead, this billboarder emulates a spheroid, and binds the screenspace projection of the spheroid with a quad. This fixes the artifacts of the AxisAligned mode

Axis aligned capsule

6 vertices / 4 triangles per particle

Particles rendered using this billboarder, like the AxisAlignedSpheroid, won’t seem to disappear at grazing angles.

Builds a 6-vertex geometry around the particle. Stretches the texture on its diagonal.

Plane aligned

4 vertices / 2 triangles per particle

Planar aligned billboarders use two axes for billboarding: like the axial billboarder, a main axis, lying on the plane, and the plane normal vector.

Material: Default_Billboard

Property	Type	Description
`BillboardingMode`	`enum`	Specifies how the billboard geometry should be build & aligned. Unless mentioned otherwise, the generated geometry will be a quad: 2 triangles, 4 vertices. ScreenAligned: Oriented to always face the camera screen plane ViewposAligned: Oriented to always face the camera position AxisAligned: Constrained along the `Axis` vector, tries facing the screen by rotating around the axis AxisAlignedSpheroid: Same as `AxisAligned`, but vertices will always enclose a spheroid, preventing the billboard from looking like a thin slice when looking along the direction of `Axis` AxisAlignedCapsule: Similar to `AxisAlignedSpheroid`, but the geometry has 4 triangles and 6 vertices, resembling a stretched cylinder instead of a spheroid PlaneAligned: Constrained on two axes, does not depend on the camera, will appear as a 3D plane
`EnableSize2D`	`bool`	When enabled, the billboard size is specified as a `float2` value, through the `Size2` property, instead of the `Size` property.
`Lit`	`bool`	Enables the Lit rendering feature: Lights the particle with the scene lights.
`LegacyLit`	`bool`	Enables the Legacy Lit rendering feature: Lights the particle with the scene lights. (legacy shader)
`SoftParticles`	`bool`	Enables the Soft Particles rendering feature: Particles fade away when becoming too close to solid scene geometry, preventing a hard clipping effect where they intersect the scene.
`FlipUVs`	`bool`	Swaps the U and V texture coordinate in the shader.
`AlphaRemap`	`bool`	Enables the Alpha Remap rendering feature: Allows remapping the alpha using a 2D grayscale texture looked up with the particle alpha along its U coordinate, and a custom per-particle `Cursor` along its V coordinate.
`Atlas`	`bool`	Enables the Atlas rendering feature: Allows to use a sprite-sheet as the diffuse texture, and control which subset of the texture is used using a per-particle `TextureID` input.
`NormalBend`	`bool`	Enables the Normal Bend rendering feature: Bends the vertex normals of the billboard to mimic a spherical surface when lighting is enabled.
`NormalWrap`	`bool`	Enables the Normal Wrap rendering feature: Remaps the `N dot L` value in the lighting equation to move back the unlit area of the billboard, and mimic subsurface scattering / partial backlighting.
`DiffuseRamp`	`bool`	Enables the Diffuse Ramp rendering feature: Uses the red channel of the diffuse texture (can be grayscale) to lookup a 1D color ramp to get the final RGB diffuse color.
`Emissive`	`bool`	Enables the Emissive rendering feature: Exposes an emissive map to use as a purely emissive color in addition to the regular diffuse component.
`TransformUVs`	`bool`	Enables the Transform UVs rendering feature: Exposes more control on the UV coordinates of the billboard corners.
`EmissiveRamp`	`bool`	Enables the Emissive Ramp rendering feature: Uses the red channel of the emissive texture (can be grayscale) to lookup a 1D color ramp to get the final RGB emissive color.
`Type`	`enum`	Transparent blending mode. Additive AdditiveNoAlpha AlphaBlend PremultipliedAlpha
`SortMode`	`enum`	Allows to specify a custom sorting key. CameraDistance: Sorts from back to front based on the particle distance to the camera (default) ByCustomValue: When selected, uses the per-particle `SortKey` input as the value to sort based on, from largest first to smallest last, like if it was a distance value.
`GlobalSortOverride`	`int`	Global sort order of the draw calls. Different values for 2 renderers will break batching and separate their drawcall. Smaller values are drawn first (visually behind higher values). The value can be negative.
`CameraSortOffset`	`float`	Used as a depth bias to allow offseting the draw call bbox along the camera axis (in world units). Different values for 2 renderers will break batching and separate their drawcall.
+ all common renderer properties
Input pins
`Position`	`float3`	Billboard center in world coordinates
`Size`	`float`	Radius of the billboard in world units
`Size2`	`float2`	2D side/up radius of the billboard in world units. Only available when `EnableSize2D` is enabled.
`Rotation`	`float`	Billboard rotation angle in degrees
`Axis`	`float3`	Principal axis of the billboard when `BillboardingMode` is set to `AxisAligned*` Side axis of the billboard when `BillboardingMode` is set to `PlaneAligned`
`NormalAxis`	`float3`	Normal of the billboard when `BillboardingMode` is set to `PlaneAligned`
`DiffuseMap`	`String`	Texture map used for the diffuse lighting component.
`Color`	`float4`	Diffuse color, multiplied with the diffuse map color.
`SortKey`	`float`	Value to be used for sorting when `SortMode` is set to `ByCustomValue`

Material: Opaque_Billboard

Property	Type	Description
`BillboardingMode`	`enum`	Specifies how the billboard geometry should be build & aligned. Unless mentioned otherwise, the generated geometry will be a quad: 2 triangles, 4 vertices. ScreenAligned: Oriented to always face the camera screen plane ViewposAligned: Oriented to always face the camera position AxisAligned: Constrained along the `Axis` vector, tries facing the screen by rotating around the axis AxisAlignedSpheroid: Same as `AxisAligned`, but vertices will always enclose a spheroid, preventing the billboard from looking like a thin slice when looking along the direction of `Axis` AxisAlignedCapsule: Similar to `AxisAlignedSpheroid`, but the geometry has 4 triangles and 6 vertices, resembling a stretched cylinder instead of a spheroid PlaneAligned: Constrained on two axes, does not depend on the camera, will appear as a 3D plane
`EnableSize2D`	`bool`	When enabled, the billboard size is specified as a `float2` value, through the `Size2` property, instead of the `Size` property.
`Lit`	`bool`	Enables the Lit rendering feature: Lights the particle with the scene lights.
`LegacyLit`	`bool`	Enables the Legacy Lit rendering feature: Lights the particle with the scene lights. (legacy shader)
`FlipUVs`	`bool`	Swaps the U and V texture coordinate in the shader.
`AlphaRemap`	`bool`	Enables the Alpha Remap rendering feature: Allows remapping the alpha using a 2D grayscale texture looked up with the particle alpha along its U coordinate, and a custom per-particle `Cursor` along its V coordinate.
`Atlas`	`bool`	Enables the Atlas rendering feature: Allows to use a sprite-sheet as the diffuse texture, and control which subset of the texture is used using a per-particle `TextureID` input.
`NormalWrap`	`bool`	Enables the Normal Wrap rendering feature: Remaps the `N dot L` value in the lighting equation to move back the unlit area of the billboard, and mimic subsurface scattering / partial backlighting.
`NormalBend`	`bool`	Enables the Normal Bend rendering feature: Bends the vertex normals of the billboard to mimic a spherical surface when lighting is enabled.
`DiffuseRamp`	`bool`	Enables the Diffuse Ramp rendering feature: Uses the red channel of the diffuse texture (can be grayscale) to lookup a 1D color ramp to get the final RGB diffuse color.
`Emissive`	`bool`	Enables the Emissive rendering feature: Exposes an emissive map to use as a purely emissive color in addition to the regular diffuse component.
`TransformUVs`	`bool`	Enables the Transform UVs rendering feature: Exposes more control on the UV coordinates of the billboard corners.
`EmissiveRamp`	`bool`	Enables the Emissive Ramp rendering feature: Uses the red channel of the emissive texture (can be grayscale) to lookup a 1D color ramp to get the final RGB emissive color.
`Type`	`enum`	Opaque mode Solid: Fully opaque, ignores the texture & color alpha channel Masked: When the final pixel’s alpha value is lower than `MaskThreshold`, the pixel is not drawn
`MaskThreshold`	`float`	Opacity mask threshold value. If the alpha value is below this value, the pixel is discarded.
+ all common renderer properties
Input pins
`Position`	`float3`	Billboard center in world coordinates
`Size`	`float`	Radius of the billboard in world units
`Size2`	`float2`	2D side/up radius of the billboard in world units. Only available when `EnableSize2D` is enabled.
`Rotation`	`float`	Billboard rotation angle in degrees
`Axis`	`float3`	Principal axis of the billboard when `BillboardingMode` is set to `AxisAligned*` Side axis of the billboard when `BillboardingMode` is set to `PlaneAligned`
`NormalAxis`	`float3`	Normal of the billboard when `BillboardingMode` is set to `PlaneAligned`
`DiffuseMap`	`String`	Texture map used for the diffuse lighting component.
`Color`	`float4`	Diffuse color, multiplied with the diffuse map color.

Material: Distortion_Billboard

Property	Type	Description
`BillboardingMode`	`enum`	Specifies how the billboard geometry should be build & aligned. Unless mentioned otherwise, the generated geometry will be a quad: 2 triangles, 4 vertices. ScreenAligned: Oriented to always face the camera screen plane ViewposAligned: Oriented to always face the camera position AxisAligned: Constrained along the `Axis` vector, tries facing the screen by rotating around the axis AxisAlignedSpheroid: Same as `AxisAligned`, but vertices will always enclose a spheroid, preventing the billboard from looking like a thin slice when looking along the direction of `Axis` AxisAlignedCapsule: Similar to `AxisAlignedSpheroid`, but the geometry has 4 triangles and 6 vertices, resembling a stretched cylinder instead of a spheroid PlaneAligned: Constrained on two axes, does not depend on the camera, will appear as a 3D plane
`EnableSize2D`	`bool`	When enabled, the billboard size is specified as a `float2` value, through the `Size2` property, instead of the `Size` property.
`SoftParticles`	`bool`	Enables the Soft Particles rendering feature: Particles fade away when becoming too close to solid scene geometry, preventing a hard clipping effect where they intersect the scene.
`FlipUVs`	`bool`	Swaps the U and V texture coordinate in the shader.
`TransformUVs`	`bool`	Enables the Transform UVs rendering feature: Exposes more control on the UV coordinates of the billboard corners.
`AlphaRemap`	`bool`	Enables the Alpha Remap rendering feature: Allows remapping the alpha using a 2D grayscale texture looked up with the particle alpha along its U coordinate, and a custom per-particle `Cursor` along its V coordinate.
`Atlas`	`bool`	Enables the Atlas rendering feature: Allows to use a sprite-sheet as the diffuse texture, and control which subset of the texture is used using a per-particle `TextureID` input.
`Lit`	`bool`	Enables the Lit rendering feature: Lights the particle with the scene lights.
`Diffuse`	`bool`	Enables the Diffuse rendering feature: Draws the particle as a regular diffuse surface in addition to distortion.
`DiffuseRamp`	`bool`	Enables the Diffuse Ramp rendering feature: Uses the red channel of the diffuse texture (can be grayscale) to lookup a 1D color ramp to get the final RGB diffuse color.
`Emissive`	`bool`	Enables the Emissive rendering feature: Exposes an emissive map to use as a purely emissive color in addition to the regular diffuse component.
`EmissiveRamp`	`bool`	Enables the Emissive Ramp rendering feature: Uses the red channel of the emissive texture (can be grayscale) to lookup a 1D color ramp to get the final RGB emissive color.
`Tint`	`bool`	Enables the Tint rendering feature: Applies a multiplicative RGB tint on the framebuffer. Useful to simulate stained glass.
+ all common renderer properties
Input pins
`Position`	`float3`	Billboard center in world coordinates
`Size`	`float`	Radius of the billboard in world units
`Size2`	`float2`	2D side/up radius of the billboard in world units. Only available when `EnableSize2D` is enabled.
`Rotation`	`float`	Billboard rotation angle in degrees
`Axis`	`float3`	Principal axis of the billboard when `BillboardingMode` is set to `AxisAligned*` Side axis of the billboard when `BillboardingMode` is set to `PlaneAligned`
`NormalAxis`	`float3`	Normal of the billboard when `BillboardingMode` is set to `PlaneAligned`

Render-features

Lit

Lights the particle with the scene lights.

Property	Type	Description
`CastShadows`	`bool`	Can cast shadows
`Roughness`	`float`	Material roughness (PBR). A roughness of `0.0` represents a mirror, a roughness of `1.0` represents a purely diffuse surface.
`Metalness`	`float`	Material metalness (PBR). A metalness of `0.0` represents a pure nonmetal, a metalness of `1.0` represents a pure metal. Affects the color of the reflections.
`Type`	`enum`	Solid Transparent
Input pins
`NormalMap`	`String`	Texture map representing tangent-space normals to be used for lighting.
`RoughMetalMap`	`String`	Roughness (R) and Metalness (G) packed in an RGBA texture
`LitMaskMap`	`String`

LegacyLit

Lights the particle with the scene lights. (legacy shader)

Property	Type	Description
`NormalWrapFactor`	`float`	Used to fake sub-surface scattering on the particles. Remaps the `N dot L` of the lighting equation from `[-1,1]` to `[-1+factor,1]`
`LightExponent`	`float`	Exponentiation of the lighting term
`LightScale`	`float3`	RGB Multiplier applied to the incoming light
`AmbientLight`	`float3`	Additional uniform light
`CastShadows`	`bool`	Can cast shadows (not implemented in editor)
Input pins
`NormalMap`	`String`	Texture map representing tangent-space normals to be used for lighting.
`SpecularMap`	`String`	Source map used in specular lighting computation

NormalBend

Bends the vertex normals of the billboard to mimic a spherical surface when lighting is enabled.

Property	Type	Description
`NormalBendingFactor`	`float`	Bending factor to apply to the billboard normals. `0.0` means no bending, the normals will be perpendicular to the billboard quad plane. `1.0` means fully bent, the normals will be tangent to the billboard quad plane, pointing outwards.

NormalWrap

Remaps the N dot L value in the lighting equation to move back the unlit area of the billboard, and mimic subsurface scattering / partial backlighting.

Property	Type	Description
`WrapFactor`	`float`	Used to fake sub-surface scattering on the particles. Remaps the `N dot L` of the lighting equation from `[-1,1]` to `[-1+factor,1]`

SoftParticles

Particles fade away when becoming too close to solid scene geometry, preventing a hard clipping effect where they intersect the scene.

Property	Type	Description
`SoftnessDistance`	`float`	Fade distance of particles in world units

AlphaRemap

Allows remapping the alpha using a 2D grayscale texture looked up with the particle alpha along its U coordinate, and a custom per-particle Cursor along its V coordinate.

Property	Type	Description
Input pins
`AlphaMap`	`String`	Texture map used as the alpha remap lookup. The `X` lookup coordinate is the diffuse texture alpha. The `Y` lookup coordinate is the `Cursor` value.
`Cursor`	`float`	`Y` coordinate used to sample the `AlphaMap` texture.

TransformUVs

Exposes more control on the UV coordinates of the billboard corners.

Property	Type	Description
`RGBOnly`	`bool`	When enabled, does not transform the UVs used to sample the alpha channel.
Input pins
`UVOffset`	`float2`	UV offset
`UVRotate`	`float2`	UV rotation angle
`UVScale`	`float2`	UV scale

Atlas

Allows to use a sprite-sheet as the diffuse texture, and control which subset of the texture is used using a per-particle TextureID input.

Property	Type	Description
`Source`	`enum`	External: Atlas tiles are defined in an external `.pkat` atlas file. Their topology can be arbitrary. Procedural: The number of tiles along the `U` and `V` axes are specified by the `SubDiv` property.
`SubDiv`	`int2`	Subdivision count
`Blending`	`enum`	Frame blending type None: No interpolation between frames Linear: Linear blending MotionVectors: Use the MotionVectorsMap texture as the interpolation vectors to blend between frames
`DistortionStrength`	`float`	Multiplier over the uv distortion Distortion strength to apply for Houdini exported maps is: `-(1.0 / FPS / ColRow)`.
Input pins
`Definition`	`String`	Atlas definition (.pkat)
`MotionVectorsMap`	`String`	Motion vectors texture, used to blend between frames when `Blending` is set to `MotionVectors`
`TextureID`	`float`	Index of the sub-rect to use inside the atlas

Diffuse

Draws the particle as a regular diffuse surface in addition to distortion.

Property	Type	Description
Input pins
`DiffuseMap`	`String`	Texture map used for the diffuse lighting component
`Color`	`float4`	Diffuse color, multiplied with the diffuse map color.

DiffuseRamp

Uses the red channel of the diffuse texture (can be grayscale) to lookup a 1D color ramp to get the final RGB diffuse color.

Property	Type	Description
Input pins
`RampMap`	`String`	1D texture map used tor for diffuse color remap. Sampled with the `Red` channel of the `DiffuseMap` texture.

Emissive

Exposes an emissive map to use as a purely emissive color in addition to the regular diffuse component.

Property	Type	Description
Input pins
`EmissiveMap`	`String`	Texture map used for the emissive lighting component.
`EmissiveColor`	`float3`	Emissive color, multiplied with the emissive texture

EmissiveRamp

Uses the red channel of the emissive texture (can be grayscale) to lookup a 1D color ramp to get the final RGB emissive color.

Property	Type	Description
Input pins
`EmissiveRamp`	`String`	1D texture map used tor for emissive color remap. Sampled with the `Red channel of the EmissiveMap texture.`

Tint

Applies a multiplicative RGB tint on the framebuffer. Useful to simulate stained glass.

Property	Type	Description
Input pins
`TintMap`	`String`	Texture map used for the tint.
`Color`	`float3`	Tint color, multiplied with the tint texture. The resulting color will be multiplied with the backbuffer values.

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PopcornFX v2.18

Overview

Geometry generation

Screen aligned

Viewpos aligned

Axis aligned

Axis aligned spheroid

Axis aligned capsule

Plane aligned

Material: Default_Billboard

Material: Opaque_Billboard

Material: Distortion_Billboard

Render-features

Lit

LegacyLit

NormalBend

NormalWrap

SoftParticles

AlphaRemap

TransformUVs

Atlas

Diffuse

DiffuseRamp

Emissive

EmissiveRamp

Tint

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