Ribbon - PopcornFX

Overview

The ribbon renderer connects particles with continuous ribbons, and maps a texture on them.
This renderer is supported in all of our public engine integrations.
Ribbons are displayed onscreen based on an input position, size, color and additional per particle or static properties.

Default Materials:

Default_Ribbon: Regular transparent ribbon (additive, alpha-blended, or premultiplied-alpha)
Opaque_Ribbon: Opaque ribbon, can use alpha-testing for cutouts
Distortion_Ribbon: Ribbon drawing in the distortion pass, useful for heat-shimmering effects

Geometry generation

The ribbon renderer connects all particles in a layer that have the same parent particle:

Particle exact positions displayed with a billboard renderer (red cross) are connected together as they have the same parent particle (EventMultiplier)
Parent particles exact position displayed with a billboard renderer (red cross) emitting trail events. Child particles have a ribbon renderer, connecting all particles with the same parent

Material: Default_Ribbon

Property	Type	Description
`BillboardingMode`	`enum`	Specifies how the ribbon geometry should be build & aligned. Unless mentioned otherwise, the generated geometry will be a quad: 2 triangles, 4 vertices. ViewposAligned: Oriented to face the camera position NormalAxisAligned: Constrained along the `Axis` vector, which represents the normal of the ribbon surface between each segment SideAxisAligned: Constrained along the `Axis` vector, which represents the axis lying on the ribbon surface between each segment, perpendicular to the ribbon direction SideAxisAlignedTube: Like `SideAxisAligned`, except the ribbon geometry will be a cylinder instead of a flat plane. The number of subdivisions of the cylinder segments is controlled by the `SegmentCount` property SideAxisAlignedMultiPlane: Like `SideAxisAligned`, except the ribbon geometry will be a collection of perpendicular planes. The number of planes is controlled by the `PlaneCount` property
`PlaneCount`	`int`	Number of intersecting ribbon planes when `BillboardingMode` is set to `SideAxisAlignedMultiPlane`.
`SegmentCount`	`int`	Number of tube subdivisions when `BillboardingMode` is set to `SideAxisAlignedTube`.
`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.
`CorrectDeformation`	`bool`	When enabled, minimizes texture shimmering artefacts when the ribbon size changes significantly from one segment to the next.
`CustomTextureU`	`bool`	Enables the CustomTextureU rendering feature: Allows to specify per-particle the `U` texture coordinate of the ribbon segment extremities.
`TextureUVs`	`bool`	Enables the TextureUVs rendering feature: Allows to independently flip the U and V texture coordinate in the shader, or rotate the UV coordinates 90 degrees clockwise.
`TextureRepeat`	`bool`	When enabled, repeats the UV coordinates instead of clamping them.
`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 ribbon 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 ribbon, 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 ribbon 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`	ribbon center in world coordinates
`Size`	`float`	Width of the ribbon in world units
`Axis`	`float3`	Normal of the ribbon surface when `BillboardingMode` is set to `NormalAxisAligned` Side axis of the ribbon when `BillboardingMode` is set to `SideAxisAligned*`
`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_Ribbon

Property	Type	Description
`BillboardingMode`	`enum`	Specifies how the ribbon geometry should be build & aligned. Unless mentioned otherwise, the generated geometry will be a quad: 2 triangles, 4 vertices. ViewposAligned: Oriented to face the camera position NormalAxisAligned: Constrained along the `Axis` vector, which represents the normal of the ribbon surface between each segment SideAxisAligned: Constrained along the `Axis` vector, which represents the axis lying on the ribbon surface between each segment, perpendicular to the ribbon direction SideAxisAlignedTube: Like `SideAxisAligned`, except the ribbon geometry will be a cylinder instead of a flat plane. The number of subdivisions of the cylinder segments is controlled by the `SegmentCount` property SideAxisAlignedMultiPlane: Like `SideAxisAligned`, except the ribbon geometry will be a collection of perpendicular planes. The number of planes is controlled by the `PlaneCount` property
`PlaneCount`	`int`	Number of intersecting ribbon planes when `BillboardingMode` is set to `SideAxisAlignedMultiPlane`.
`SegmentCount`	`int`	Number of tube subdivisions when `BillboardingMode` is set to `SideAxisAlignedTube`.
`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)
`CorrectDeformation`	`bool`	When enabled, minimizes texture shimmering artefacts when the ribbon size changes significantly from one segment to the next.
`CustomTextureU`	`bool`	Enables the CustomTextureU rendering feature: Allows to specify per-particle the `U` texture coordinate of the ribbon segment extremities.
`TextureUVs`	`bool`	Enables the TextureUVs rendering feature: Allows to independently flip the U and V texture coordinate in the shader, or rotate the UV coordinates 90 degrees clockwise.
`TextureRepeat`	`bool`	When enabled, repeats the UV coordinates instead of clamping them.
`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 ribbon, and mimic subsurface scattering / partial backlighting.
`NormalBend`	`bool`	Enables the Normal Bend rendering feature: Bends the vertex normals of the ribbon 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 ribbon 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`	Ribbon center in world coordinates
`Size`	`float`	Width of the ribbon in world units
`Axis`	`float3`	Normal of the ribbon surface when `BillboardingMode` is set to `NormalAxisAligned` Side axis of the ribbon when `BillboardingMode` is set to `SideAxisAligned*`
`DiffuseMap`	`String`	Texture map used for the diffuse lighting component.
`Color`	`float4`	Diffuse color, multiplied with the diffuse map color.

Material: Distortion_Ribbon

Property	Type	Description
`BillboardingMode`	`enum`	Specifies how the ribbon geometry should be build & aligned. Unless mentioned otherwise, the generated geometry will be a quad: 2 triangles, 4 vertices. ViewposAligned: Oriented to face the camera position NormalAxisAligned: Constrained along the `Axis` vector, which represents the normal of the ribbon surface between each segment SideAxisAligned: Constrained along the `Axis` vector, which represents the axis lying on the ribbon surface between each segment, perpendicular to the ribbon direction SideAxisAlignedTube: Like `SideAxisAligned`, except the ribbon geometry will be a cylinder instead of a flat plane. The number of subdivisions of the cylinder segments is controlled by the `SegmentCount` property SideAxisAlignedMultiPlane: Like `SideAxisAligned`, except the ribbon geometry will be a collection of perpendicular planes. The number of planes is controlled by the `PlaneCount` property
`PlaneCount`	`int`	Number of intersecting ribbon planes when `BillboardingMode` is set to `SideAxisAlignedMultiPlane`.
`SegmentCount`	`int`	Number of tube subdivisions when `BillboardingMode` is set to `SideAxisAlignedTube`.
`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.
`CorrectDeformation`	`bool`	When enabled, minimizes texture shimmering artefacts when the ribbon size changes significantly from one segment to the next.
`CustomTextureU`	`bool`	Enables the CustomTextureU rendering feature: Allows to specify per-particle the `U` texture coordinate of the ribbon segment extremities.
`TextureUVs`	`bool`	Enables the TextureUVs rendering feature: Allows to independently flip the U and V texture coordinate in the shader, or rotate the UV coordinates 90 degrees clockwise.
`TextureRepeat`	`bool`	When enabled, repeats the UV coordinates instead of clamping them.
`TransformUVs`	`bool`	Enables the Transform UVs rendering feature: Exposes more control on the UV coordinates of the ribbon corners.
`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`	Ribbon center in world coordinates
`Size`	`float`	Width of the ribbon in world units
`Axis`	`float3`	Normal of the ribbon surface when `BillboardingMode` is set to `NormalAxisAligned` Side axis of the ribbon when `BillboardingMode` is set to `SideAxisAligned*`

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 ribbon to mimic a spherical surface when lighting is enabled.

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

NormalWrap

Remaps the N dot L value in the lighting equation to move back the unlit area of the ribbon, 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.

TextureUVs

Allows to independently flip the U and V texture coordinate in the shader, or rotate the UV coordinates 90 degrees clockwise.

Property	Type	Description
`FlipU`	`bool`	When enabled, flips the `U` texture coordinate.
`FlipV`	`bool`	When enabled, flips the `V` texture coordinate.
`RotateTexture`	`bool`	When enabled, rotates the texture coordinates 90 degrees clockwise. (`TextureU`, `FlipU`, and `FlipV` are rotated too)

TransformUVs

Exposes more control on the UV coordinates of the ribbon 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.

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PopcornFX v2.18