Source: core/renderers/webgl/systems/shader/shader/mapSize.js

const GLSL_TO_SIZE = {
    float:    1,
    vec2:     2,
    vec3:     3,
    vec4:     4,

    int:      1,
    ivec2:    2,
    ivec3:    3,
    ivec4:    4,

    bool:     1,
    bvec2:    2,
    bvec3:    3,
    bvec4:    4,

    mat2:     4,
    mat3:     9,
    mat4:     16,

    sampler2D:  1,
};

/**
 * @class
 * @memberof PIXI.glCore.shader
 * @param type {String}
 * @return {Number}
 */
export default function mapSize(type)
{
    return GLSL_TO_SIZE[type];
}