tangram/src/gl/vao.js

WebGL Maps for Vector Tiles

// Creates a Vertex Array Object if the extension is available, or falls back on standard attribute calls

import getExtension from './extensions';
import log from '../utils/log';

export default {

    disabled: false, // set to true to disable VAOs even if extension is available
    bound_vao: [],   // currently bound VAO, by GL context

    init (gl) {
        let ext;
        if (this.disabled !== true) {
            ext = getExtension(gl, 'OES_vertex_array_object');
        }

        if (ext != null) {
            log('info', 'Vertex Array Object extension available');
        }
        else if (this.disabled !== true) {
            log('warn', 'Vertex Array Object extension NOT available');
        }
        else {
            log('warn', 'Vertex Array Object extension force disabled');
        }
    },

    getExtension(gl, ext_name) {
        if (this.disabled !== true) {
            return getExtension(gl, ext_name);
        }
    },

    create (gl, setup, teardown) {
        let vao = {};
        vao.setup = setup;
        vao.teardown = teardown;

        let ext = this.getExtension(gl, 'OES_vertex_array_object');
        if (ext != null) {
            vao._vao = ext.createVertexArrayOES();
            ext.bindVertexArrayOES(vao._vao);
        }

        vao.setup();

        return vao;
    },

    getCurrentBinding (gl) {
        let bound = this.bound_vao.filter(e => e[0] === gl)[0];
        return bound && bound[1];
    },

    setCurrentBinding (gl, vao) {
        let bound_vao = this.bound_vao;
        let binding = bound_vao.filter(e => e[0] === gl)[0];
        if (binding == null) {
            bound_vao.push([gl, vao]);
        }
        else {
            binding[1] = vao;
        }
    },

    bind (gl, vao) {
        let ext = this.getExtension(gl, 'OES_vertex_array_object');
        if (vao != null) {
            if (ext != null && vao._vao != null) {
                ext.bindVertexArrayOES(vao._vao);
                this.setCurrentBinding(gl, vao);
            }
            else {
                vao.setup();
            }
        }
        else {
            let bound_vao = this.getCurrentBinding(gl);
            if (ext != null) {
                ext.bindVertexArrayOES(null);
            }
            else if (bound_vao != null && typeof bound_vao.teardown === 'function') {
                bound_vao.teardown();
            }
            this.setCurrentBinding(gl, null);
        }
    },

    destroy (gl, vao) {
        let ext = this.getExtension(gl, 'OES_vertex_array_object');
        if (ext != null && vao != null && vao._vao != null) {
            ext.deleteVertexArrayOES(vao._vao);
            vao._vao = null;
        }
        // destroy is a no-op if VAO extension isn't available
    }

};