I'm currently working on programming a three.js scene using a PerspectiveCamera. The goal is to display a specific sub-region of the entire camera view within the canvas, with the ability to zoom in. I have meticulously reviewed my offset values and confirmed that the zoom factor aligns logically.
When fully vertically fitted, the parameters are as follows:
current zoom 1
x 714.4099378881989 y 0 w 3755.1801242236024 h 3888
Initially, everything functions correctly when the zoom is set to 1. However, once the zoom factor is modified, the alignment goes awry. Surprisingly, increasing the zoom beyond 1 works seamlessly without any offsets, focusing on the frustum's center. Despite utilizing TrackballControls, they should not affect this scenario since all values are being configured through code.
The relevant function responsible for updating the camera in the PerspectiveCamera class is as follows:
updateProjectionMatrix: function () {
var near = this.near,
top = near * Math.tan( _Math.DEG2RAD * 0.5 * this.fov ) / this.zoom,
height = 2 * top,
width = this.aspect * height,
left = - 0.5 * width,
view = this.view;
if ( this.view !== null && this.view.enabled ) {
var fullWidth = view.fullWidth,
fullHeight = view.fullHeight;
left += view.offsetX * width / fullWidth;
top -= view.offsetY * height / fullHeight;
width *= view.width / fullWidth;
height *= view.height / fullHeight;
}
var skew = this.filmOffset;
if ( skew !== 0 ) left += near * skew / this.getFilmWidth();
this.projectionMatrix.makePerspective( left, left + width, top, top - height, near, this.far );
this.projectionMatrixInverse.getInverse( this.projectionMatrix );
},
Upon initial analysis, it seems like the field of view (fov) pertains to the complete view rather than adjusting for sub-views. Alternatively, it might be necessary to divide the zoom by a factor based on the sub-view dimensions, but I am unsure where to commence in resolving this issue.