regl-camera

A basic reusable "turntable" camera component for regl. (Secretly just spherical coordinates.)

Example

const regl = require('regl')()
const camera = require('regl-camera')(regl, {
  center: [0, 2.5, 0]
})

const bunny = require('bunny')
const normals = require('angle-normals')

const drawBunny = regl({
  frag: `
    precision mediump float;
    varying vec3 vnormal;
    void main () {
      gl_FragColor = vec4(abs(vnormal), 1.0);
    }`,
  vert: `
    precision mediump float;
    uniform mat4 projection, view;
    attribute vec3 position, normal;
    varying vec3 vnormal;
    void main () {
      vnormal = normal;
      gl_Position = projection * view * vec4(position, 1.0);
    }`,
  attributes: {
    position: bunny.positions,
    normal: normals(bunny.cells, bunny.positions)
  },
  elements: bunny.cells
})

regl.frame(() => {
  camera((state) => {
    if (!state.dirty) return;
    regl.clear({color: [0, 0, 0, 1]})
    drawBunny()
  })
})

Install

npm i regl-camera

API

Constructor

var camera = require('regl-camera')(regl[, options])

module.exports of regl-camera is a constructor for the camera. It takes the following arguments:

• regl is a handle to the regl instance
• options is an object with the following optional properties:
  • center which is the center of the camera
  • theta the theta angle for the camera
  • phi the phi angle for the camera
  • distance the distance from the camera eye to the center
  • up is the up vector for the camera
  • fovy is the field of view angle in y direction (defaults to Math.PI / 4)
  • near is the near clipping plane in z (defaults to 0.01)
  • far is the far clipping plane in z (defaults to 1000.0)
  • mouse set to false to turn off mouse events
  • damping multiplier for inertial damping (default 0.9). Set to 0 to disable inertia.
  • noScroll boolean flag to prevent mouse wheel from scrolling the whole window. Default is false.
  • element is an optional DOM element for mouse events (defaults to regl canvas element)
  • rotationSpeed the rotation interactions (default: 1)
  • zoomSpeed the zoom interactions (default: 1)
  • renderOnDirty boolean flag to control whether scene is only rendered when the camera state has changed. If true, render can be triggerd at any time by setting camer.dirty = true. If false, dirty state can still be detected and used through context.dirty.

Command usage

camera(block)

regl-camera sets up an environment with the following variables in both the context and uniform blocks:

Variable	Type	Description
view	mat4	The view matrix for the camera
projection	mat4	The projection matrix for the camera
center	vec3	The center of the camera
eye	vec3	The eye coordinates of the camera
up	vec3	The up vector for the camera matrix
theta	float	Latitude angle parameter in radians
phi	float	Longitude angle parameter in radians
distance	float	Distance from camera to center of objective
dirty	boolean	Flag set to true when camera state has changed

Note These properties can also be accessed and modified directly by accessing the object, though at the moment you will need to manually set camera.dirty = true if relying upon renderOnDirty

License

(c) 2016 Mikola Lysenko. MIT License