Test.cs

using UnityEngine;

public class Test : MonoBehaviour {
	public TpAtlas atlas;
	public TpSprite sprite;

	void OnEnable() {
		var text = Resources.Load<TextAsset>("ui").text;
		atlas = JsonUtility.FromJson<TpAtlas>(text);
		var size = atlas.size;

		foreach (var s in atlas.sprites) {
			if (s.name == "block_fade") {
				sprite = s;
				break;
			}
		}

		var material = new Material(Shader.Find("Sprites/Default"));
		var texture = new Texture2D(0, 0);
		texture.LoadImage(Resources.Load<TextAsset>(atlas.name).bytes);
		texture.Apply();
		material.mainTexture = texture;
		GetComponent<MeshRenderer>().sharedMaterial = material;


		var mesh = GetComponent<MeshFilter>().mesh;
		mesh.MarkDynamic();

		// v0 - v1
		// |  \ |
		// v3 - v2
		var pivot = sprite.pivot;
		var quad = sprite.quad;
		var uv = sprite.uv;

		var vertices = new Vector3[4];
		var uvs = new Vector2[4];

		vertices[0].Set(-pivot.x + quad.x, pivot.y - quad.y, 0);
		vertices[1].Set(-pivot.x + quad.x + quad.w, pivot.y - quad.y, 0);
		vertices[2].Set(-pivot.x + quad.x + quad.w, pivot.y - quad.y - quad.h, 0);
		vertices[3].Set(-pivot.x + quad.x, pivot.y - quad.y - quad.h, 0);

		if (!sprite.rotated) {
			uvs[0].Set(uv.x / size.x, -uv.y / size.y);
			uvs[1].Set((uv.x + uv.w) / size.x, -uv.y / size.y);
			uvs[2].Set((uv.x + uv.w) / size.x, (-uv.y - uv.h) / size.y);
			uvs[3].Set(uv.x / size.x, (-uv.y - uv.h) / size.y);
		} else {
			uvs[0].Set((uv.x + uv.w) / size.x, -uv.y / size.y);
			uvs[1].Set((uv.x + uv.w) / size.x, (-uv.y - uv.h) / size.y);
			uvs[2].Set(uv.x / size.x, (-uv.y - uv.h) / size.y);
			uvs[3].Set(uv.x / size.x, -uv.y / size.y);
		}

		mesh.vertices = vertices;
		mesh.uv = uvs;
		mesh.triangles = new [] { 0, 1, 2, 0, 2, 3 };

		Debug.Log(Time.time);
	}
}