VfxPrimitiveArbitraryQuad

Inheritance 2 ancestors · 8 siblings

• VfxPrimitiveBase
  • VfxLegacyPrimitiveBase
    • VfxPrimitiveArbitraryQuadcurrent
    • VfxPrimitiveBeam
    • VfxPrimitiveBeamBase1
    • VfxPrimitiveCameraQuad1
    • VfxPrimitiveMeshBase2
    • VfxPrimitiveNonRenderable
    • VfxPrimitiveProjectionBase1
    • VfxPrimitiveRay
    • VfxPrimitiveTrailBase2

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A quad in the plane of the particle's own local X and Y axes, not facing the camera. The axes come from the particle's full orientation - its rotation, combined with the emitter's and the system's orientation - so the quad can lie flat on the ground, stand upright or tumble in 3D.

Size. The corners are position ± scale.x · X ± scale.y · Y, so the quad is 2 · scale.x by 2 · scale.y. scale.z is not read, and the local Z axis plays no part in the shape.

Orientation. With no rotation authored, the quad stands upright in the emitter's local XY plane, facing along the emitter's forward axis (+Z). A rotation of 90 degrees about X, such as a BirthRotation0 of [90, 0, 0], lays it flat. When the emitter sets IsDirectionOriented, the particle's orientation is rebuilt from its direction of travel every frame, and the quad turns with it.

Texture. The mapping is the camera quad's with the two axes swapped. Before the emitter's UV properties apply:

u = y + 0.5      // along local +Y
v = 0.5 - x      // against local +X

where x and y run from -0.5 to 0.5 across the quad. The top of the image lies along +X and its left edge along -Y, so a texture that reads upright on a camera quad appears turned a quarter turn here.