pEmitter

pEmitter normally starts a particle branch. It does not process a MediaIn frame and it does not output RGBA; it creates particle data that can pass through particle modifiers and must ultimately reach pRender.

Its most important topology rule is that the default node has no inputs. A permanent Input, Background, Effect Mask or Region socket would be misleading.

Selecting Bitmap in the Style tab creates a dynamic Style Bitmap image input. That image is duplicated as the visual particle cell and is not the emission region.

Selecting Bitmap or Mesh in the Region tab creates a separate dynamic Region input. Bitmap supplies a 2D image/channel for birth positions; Mesh supplies 3D geometry. Style Bitmap and Region may use the same source, but they serve different roles.

Controls define birth behavior. Number is the number of new particles generated per frame, Lifespan defines how long each particle survives, and Number/Lifespan Variance break up mechanical repetition.

Color Source chooses between Style Color and Color From Region. Color From Region is meaningful with a Bitmap Region; the Resolve 21 manual warns that non-bitmap regions can yield white particles in that mode.

Position Variance softens the emitter boundary by allowing particles to be born slightly outside the exact Region boundary.

Temporal Distribution controls birth timing inside each frame. At The Same Time uses frame boundaries, while Randomly and Evenly Distributed use subframes and therefore depend on pRender Sub-Frame Accuracy.

Velocity is initial motion at birth. It is not the same as pDirectionalForce: the emitter sets the starting state while force nodes continue changing existing particles on later frames.

Inherit Velocity transfers movement of the emitter Region to newly created particles. Negative values can reverse inherited motion, 1 approximately matches Region velocity and 2 moves particles ahead of it.

Angle specifies the X/Y heading and Angle Z specifies depth heading. Variance controls spread around those directions.

Rotation Mode separates absolute orientation from Rotation Relative To Motion. In the relative mode, the particle follows its motion heading and Rotation acts as an offset.

Rotation sets initial orientation while Spin changes orientation over time. Symmetric Point or spherical particles can hide otherwise valid rotation settings.

Set 1–32 is assigned by pEmitter. Downstream particle nodes then filter those memberships with their own Set Mode; assigning a Set does not by itself change the visible result.

Style controls particle appearance. Point is the lightest diagnostic style; Bitmap uses the dynamic image input; Blob is soft, Brush uses an image from the Brushes directory, Line exposes motion direction and Point Cluster groups multiple points into one cell.

Bitmap Style can address an animated source by composition time, each particle's age, or each particle's birth time. These modes are not interchangeable.

Color Over Life, Size Over Life, Fade and Blur Over Life are normalized to particle lifespan, so the same curve scales with particles that live for different numbers of frames.

Merge and Blur style controls apply to 2D particle rendering and should not be used as substitutes for 3D scene geometry.

Region on pEmitter is birth geometry rather than a behavioral gate. Only one emitter Region is active for a given pEmitter.

All, Bezier, Cube, Line, Rectangle and Sphere are generated internally. Bitmap and Mesh are the modes that require a dynamic external Region input.

In 2D output, emitter geometry is effectively evaluated on a Z plane. In 3D workflows, Cube, Sphere and Mesh can create particles with depth.

Mesh Region can use Surface or Volume behavior. Winding Rule and Winding Ray Direction help interpret imperfect or open meshes, and ObjectID filtering can isolate part of an incoming mesh.

Performance costs multiply: high Number, long Lifespan, large Bitmap cells and high subframe accuracy can all be expensive. Prove motion with Point and low density before increasing quality.

Keep Random Seed fixed while comparing controls. Randomize/Reseed should create a new procedural variation, not hide a broken setup.

Treat pEmitter as a data generator, not a finished effect. Start with pEmitter -> pRender, then add pDirectionalForce, pTurbulence, pFriction, pSpawn, pBounce or other particle tools one at a time.