the scene

one component, several projections

The scene is one component. A projection is a pair of functions, from a direction to a point on the screen and back. Drawing, hit-testing, dragging and hover are written once against that pair, so a new view costs about fifteen lines.

view	what it is	editable
globe	the sphere seen from outside, turnable	yes
equirect	azimuth across, elevation up, flat	yes, and the one place elevation is set directly

The graticule, paths and regions live in world space and are drawn through whichever projection, so no view has a seam to special-case.

interaction

• A drag and a click are told apart by movement, 4 pixels of slop, never by where the press was.
• A view that turns keeps dragging for the camera. A flat view has no camera, so a press can place and drag in one gesture. The difference follows from the camera; forcing the two to match makes both worse.
• Nothing is dragged that is not free to move. An encoder’s source is on its path, so dragging it turns the view instead.
• A held handle is re-applied every frame, not only when the pointer moves, so a region turning under a rate does not slip out from under a still pointer.

the colours

	what it means
orange	what came into the plugin
blue	what this plugin added

It reads the same in every plugin. In the encoder, orange is the source’s position and blue the field it encodes; in an effect, orange is the incoming field’s energy and blue what the effect adds. The two are never mixed: a point of the picture is one or the other.

These are roles in the theme, separate from the controls’ colours. Changing one never moves the other.

the energy picture

Every plugin can show energy by direction, drawn through the same projections as everything else. It is the one thing in a window that costs, so it is off when a window opens, and while it is off the audio thread gathers nothing. The audio thread hands over a small per-block summary of the field and never draws.

A window can show another instance’s energy: it asks, and that instance gathers only while someone is asking.

regions in the scene

A region is drawn in ink, so colour stays with what came in and what was added: its edge at the half-way contour, and a light wash where it fades, under the energy. While its tab is open it shows handles, and the energy dims to half so the wash can be seen. Another instance’s region is a dotted grey edge. regions always decides whether every region shows or only the one being edited.

the probe

Point at a direction, and the plugin shows what it would do to a sound from there. One component; each plugin supplies the answer. Echo draws every tap’s repeats as they travel; Reverb draws the early reflections where they arrive.

The probe is worked out from the parameters, never from audio, so it costs the audio thread nothing and answers while nothing plays. The direction in is drawn in the incoming colour, the answer in the added colour. It is an indicator of what would happen, not a measurement, and the measured energy is drawn beside it.

A field effect cannot know where its sources are; it only sees a field. What it can always answer is what it would do to a direction it is pointed at. That is why effects have a probe where the encoder has a source.

what the tests cannot see

Tests check what is computed, not what is drawn, and a defect in the drawing passes all of them. Look at the picture: the picture tools draw every view to a PNG. See building and checking.