SpectraMap documentation

Canvases and sources

A canvas is a pixel space that matches a physical surface. A source is something that produces frames. A mapping places a rectangle of a source onto a rectangle of the canvas.

Mappings may overlap

Deliberately. Later mappings draw over earlier ones, so a lower-third sits on top of a background by being added after it. Order is the compositing model — there are no separate layers to manage.

Crop and scale

Every mapping has a source rectangle and a destination rectangle. Different sizes scale; a smaller source rectangle crops. Set both numerically — dragging by eye is how you end up one pixel off on a 6 metre wall, which is visible from the back of the room.

Multiple canvases

Use one canvas per physical surface. A main wall and two side panels fed different content are three canvases, not one wide one with gaps — that keeps each output’s region arithmetic simple and survives a last-minute change to one surface.

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