Unit sphere generation

SphereGeneration.kt

val unitSphere: Primitive by lazy {
    fun sphere(u: Float, v: Float): Vector3f =
        Vector3f(MathF.cos(u) * MathF.sin(v), MathF.cos(v), MathF.sin(u) * MathF.sin(v))

    val vertices = ArrayList<Float>()
    val resolution = 20
    val startU = 0F
    val startV = 0F
    val endU = MathF.PI * 2F
    val endV = MathF.PI
    val stepU = (endU - startU) / resolution.toFloat()
    val stepV = (endV - startV) / resolution.toFloat()

    for (i in 0 until resolution) {
        for (j in 0 until resolution) {
            val u = i * stepU + startU
            val v = j * stepV + startV
            val un = if (i + 1 == resolution) endU else (i + 1) * stepU + startU
            val vn = if (j + 1 == resolution) endV else (j + 1) * stepV + startV

            val p0 = sphere(u, v)
            val p1 = sphere(u, vn)
            val p2 = sphere(un, v)
            val p3 = sphere(un, vn)

            addTriangle(p0, p2, p1)
            addTriangle(p3, p1, p2)
        }
    }

    Primitive(vertices.toFloatArray(), GL_TRIANGLES, 3)
}