Subimaging for THREE.Texture

Just some inspiration for a subimaging approach, how I did it…

THREE.Texture = function... {
        ...
        this._subImages = [];
        ...
}


    addSubImage: function( offsetX, offsetY, image) {

        this._subImages.push( {
            _subOffsetX: offsetX,
            _subOffsetY: offsetY,
            image: image
        } );

        this.needsUpdate = true;
    },





//from WebGLRenderer
this.setTexture = function ( texture, slot ) {
        ...
        // the code for regular textures  with auto generated mipmaps:
        if ( texture._subImages.length == 0 ) {

        _gl.texImage2D( _gl.TEXTURE_2D, 0, glFormat, glFormat, glType, texture.image );

    } else {                

        for ( var i = 0, il = texture._subImages.length; i < il; i ++ ) {

            _gl.texSubImage2D( _gl.TEXTURE_2D, 0, texture._subImages[ i ]._subOffsetX, texture._subImages[ i ]._subOffsetY, glFormat, glType, texture._subImages[ i ].image );

        }

        texture._subImages = [];

    }
        ...
};

… if I find time I might code it out one day, but this would have to be done for all renderers and all cases I guess (CompressedTexture, DataTexture?, Cubestuff?, etc.)

Ah well the benefit… the benefit is performance and fancyness I guess. Replacing parts of a texture is cool 👍 And e.g. for spritesheets it’s way faster than instantiating a new texture every time.

Soooo searching for volunteer! 😄

[FreakTheMighty]

This would be quite useful to our project. We’re working with spherical panoramas and I’ve found a bottle neck loading textures with size 4096x2048 on mobile devices. textImage2d blocks the UI thread for a little over half a second. I may change to cubic maps, but functionality like this would be pretty useful.

@arcanis I can work on testing your implementation.

[mrdoob]

#13512