Function getProjectionParameters

docs/app/js/sanddance-app.js:80402–80418

(options)

    return vm;
}
function getProjectionParameters(options) {
    const { width , height , altitude , pitch =0 , nearZMultiplier =1 , farZMultiplier =1  } = options;
    let { fovy =altitudeToFovy(DEFAULT_ALTITUDE)  } = options;
    if (altitude !== undefined) fovy = altitudeToFovy(altitude);
    const halfFov = 0.5 * fovy * DEGREES_TO_RADIANS;
    const focalDistance = fovyToAltitude(fovy);
    const pitchRadians = pitch * DEGREES_TO_RADIANS;
    const topHalfSurfaceDistance = Math.sin(halfFov) * focalDistance / Math.sin(Math.min(Math.max(Math.PI / 2 - pitchRadians - halfFov, 0.01), Math.PI - 0.01));
    const farZ = Math.sin(pitchRadians) * topHalfSurfaceDistance + focalDistance;
    return {
        fov: 2 * halfFov,
        aspect: width / height,
        focalDistance,
        near: nearZMultiplier,
        far: farZ * farZMultiplier
    };
}
function getProjectionMatrix(options) {
    const { fov , aspect , near , far  } = getProjectionParameters(options);
    const projectionMatrix = _mat4.perspective([], fov, aspect, near, far);