Source: packages/core/src/textures/resources/DepthResource.js

import { ALPHA_MODES } from '@pixi/constants';
import { BufferResource } from './BufferResource';
/**
 * Resource type for DepthTexture.
 * @class
 * @extends PIXI.resources.BufferResource
 * @memberof PIXI.resources
 */
export class DepthResource extends BufferResource
{
    /**
     * Upload the texture to the GPU.
     * @param {PIXI.Renderer} renderer Upload to the renderer
     * @param {PIXI.BaseTexture} baseTexture Reference to parent texture
     * @param {PIXI.GLTexture} glTexture glTexture
     * @returns {boolean} true is success
     */
    upload(renderer, baseTexture, glTexture)
    {
        const gl = renderer.gl;

        gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, baseTexture.alphaMode === ALPHA_MODES.UNPACK);
        if (glTexture.width === baseTexture.width && glTexture.height === baseTexture.height)
        {
            gl.texSubImage2D(baseTexture.target, 0, 0, 0, baseTexture.width, baseTexture.height, baseTexture.format, baseTexture.type, this.data);
        }
        else
        {
            glTexture.width = baseTexture.width;
            glTexture.height = baseTexture.height;
            gl.texImage2D(baseTexture.target, 0,
            //  gl.DEPTH_COMPONENT16 Needed for depth to render properly in webgl2.0
                renderer.context.webGLVersion === 1 ? gl.DEPTH_COMPONENT : gl.DEPTH_COMPONENT16, baseTexture.width, baseTexture.height, 0, baseTexture.format, baseTexture.type, this.data);
        }

        return true;
    }
}