_swapPasses() {
        // swap read and write passes
        const tempFBO = this.readPass;
        this.readPass = this.writePass;
        this.writePass = tempFBO;

        // apply new texture
        this.textures[0].copy(this.readPass.getTexture());
    }
After each draw call, we'll swap the 2 render targets and copy the read pass texture again
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