Fundamentals to decide on for 1/31 about api

[azaroth42]

Properties of Scenes:

• General: Turning on and off features of different entities; possibly via behaviors
• Camera constraints sensible -- don't zoom into the middle of a model; don't look at the back/bottom of an incomplete model
• What should be possible/impossible to describe/define?
• navigationMode as a (synthetic?) property
• collision detection? model to look at vs space to move through
• Difference between publisher saying "don't show this scene other than from this point" vs "this camera can only do this"
• "inheritance" on/off
• Scene with duration can't go into non-duration scene
• +Z is front

Transform model:

• Transform model okay
• No need to move pivot point
• Can't have multiple pivots without multiple scenes/models

Cameras

• Types: Perspective, Orthographic/Orthogonal
• Camera is optional ; the first camera found in order in the manifest, then that is the default camera
• Multiple cameras are choices
• Cannot scale a camera
• Initial state: at the origin, looking at -INF in Z
• (Question: orbit of camera / interaction)
• Properties: field of view - angle in degrees, bottom to top
• Properties: near and far, each floating point value in units of scene's dimensional space, optional

General Notes:
Orthographic camera isn't "in" the scene, like directional light.

[azaroth42]

• +Y is up for scenes
• follow and orbit are similar but distinct
• Scale on cameras does make sense, as you're scaling the local coordinate space (an otherwise empty scene apart from the camera) to then map into the target scene's coordinate space
• lookAt on camera object -- value is a reference to a point, either by a point selector or an annotation that has a target in the scene (not a model)
• Question about multiple target painting annotations -- disallow or not?
• Order of operations -- lookAt is the last thing, so cannot rotate/translate after looking at something
• Origin or Centroid -- behavior on camera to swap between

[azaroth42]

Lights

• Properties: color, RGB space
• Properties: intensity, array of construct {"value": float, "unit": "relative"} (or "lumens" or "whatever"), multiple equivalents possible
• Directional Light default is straight down. Then rotate from there with a RotateTransform. Don't use explicit vector, yes to lookAt with a pointSelector to calculate the vector from.
• Position is ignored for Ambient or Directional, so annotate the scene.
• Don't specify decay (at least for now)
• Spotlights - no decay, no penumbra, angle property on the light with degrees. maximum of 180 degrees.
• Lights are optional, viewer should make sure there's some way to see the scene.
• behavior around objects casting shadows -- light has casting flag, annotation has a 'receives shadows' flag for whether it should show shadows from objects.
• Note about hidden
• default color is white and intensity is viewer dependent (reasonable)

[azaroth42]

Turning on/off:

• Flag on annotation of whether to include the cameras or lights that are in the scene or model in the body, e.g. no-cameras, no-lights
• Note that you can't selectively import lights or cameras from within a model/scene