Regl-inertia-camera NPM

regl-inertia-camera

A 3D spherical coordinate camera for regl, for desktop and mobile

Introduction

A 3D spherical coordinate camera with rotation, panning, zooming, and pivoting (i.e. yaw and pitch). Designed to function on desktop and mobile.

Example

const camera = require('regl-inertia-camera')(regl, {
  phi: 0.5,
  theta: 1,
  distance: 20,
});

camera(() => {
  reglDrawCmd();
});

See demo.js for fully worked example.

Usage

`camera = require('regl-inertia-camera')(regl[, opts])`

Given existing regl instance and options, returns a camera instance which sets camera projection and view matrix context and uniforms. For convenience, view, projection and eye are exposed through regl context variables as well as uniforms. Configuration options are:

Option	Type	Default	Meaning
`element`	HTML element	`window`	element to which to attach
`viewUniformName`	String	`view`	name of view matrix uniform
`projectionUniformName`	String	`projection`	name of projection matrix uniform
`eyeUniformName`	String	`eye`	name of eye vector uniform

The camera may be invoked as:

camera(state, callback)

where state is an object containing changes to the camera state variables, defined below, and callback is a function invoked within the regl context of the camera. Callback receives camera.state as its parameter.

The returned camera contains the following computed properties which will be overwritten on every draw frame and so cannot (meaningfully) be modified:

Camera variable	Type	Meaning
`aspectRatio`	Number	current aspect ratio
`eye`	vec3	location of camera
`height`	Number	current height of view
`projection`	mat4	projection matrix
`projectionInv`	mat4	inverse projection matrix
`view`	mat4	view matrix
`viewInv`	mat4	inverese view matrix
`width`	Number	current width of view

The returned camera contains a .state property which contains the following state values, all of which may be written directly. On each invocation of draw these parameters will be checked for differences and will trigger a dirty camera where applicable so that the view is redrawn automatically.

State variable	Type	Default/Initial	Meaning
`center`	vec3	`[0, 0, 0]`	point at the center of the view
`distance`	Number	`10`	distance of eye from center
`dirty`	Boolean	`true`	true when camera view has changed
`dPhi`	Number	`0`	current phi inertia of camera
`dTheta`	Number	`0`	current theta inertia of camera
`enablePan`	Boolean	`true`	allow panning
`enablePivot`	Boolean	`true`	allow pivoting (yaw and pitch) of view
`enableRotation`	Boolean	`true`	allow rotation view
`enableZoom`	Boolean	`true`	allow zooming of view
`far`	Number	`100`	far clipping plane
`fovY`	Number	`π / 4`	field of view in the vertical direction, in radians
`near`	Number	`0.1`	near clipping plane
`panDecayTime`	Number	`100`	half life of panning inertia in ms
`panX`	Number	`0`	current horizontal amount to pan at next draw
`panY`	Number	`0`	current vertical amount to pan at next draw
`panZ`	Number	`0`	current in/out of plane amount to pan at next draw
`phi`	Number	`0`	azimuthal angle of camera
`pitch`	Number	`0`	current amount to pitch at next draw, in radians
`rotationCenter`	vec3	`[0, 0, 0]`	point about which the view rotates
`rotationSpeed`	Number	`1.0`	Speed of rotation interaction
`rotationDecayTime`	Number	`100`	half life of rotation inertia in ms
`rotateAboutCenter`	Boolean	`false`	If false, rotate about `rotationCenter`, otherwise rotates about the current view center.
`theta`	Number	`0`	horizontal rotation of camera
`up`	vec3	`[0, 1, 0]`	vertical direction
`wheelSpeed`	Number	`1.0`	Speed of mouse wheel interaction
`x0`	Number	`null`	current horizontal location of interaction, in pixels
`y0`	Number	`null`	current vertical location of interaction, in pixels
`yaw`	Number	`0`	current amount to yaw at next draw, in radians
`zoom`	Number	`0`	current amount to zoom at next draw (0 = no change)
`zoomDecayTime`	Number	`100`	half life of zooming inertia in ms