using UnityEngine;

public class TextureCombiner : MonoBehaviour
{
    // 定义单个图片的信息结构
    [System.Serializable]
    public struct TextureInfo
    {
        public Texture2D texture;
        public Vector2 position;
        public float rotation;
        public Vector2 scale;
    }

    public TextureInfo[] textureInfos;

    public Texture2D CombineTextures(int width, int height)
    {
        RenderTexture rt = RenderTexture.GetTemporary(width, height, 0);
        RenderTexture.active = rt;

        GL.Clear(true, true, Color.clear);
        GL.PushMatrix();

        // 创建正交相机矩阵
        Matrix4x4 orthoMatrix = Matrix4x4.Ortho(0, width, 0, height, -1, 1);
        GL.LoadProjectionMatrix(orthoMatrix);

        Material blitMaterial = new Material(Shader.Find("Unlit/Texture"));

        foreach (TextureInfo info in textureInfos)
        {
            GL.PushMatrix();

            // 创建变换矩阵
            Matrix4x4 transformMatrix = Matrix4x4.TRS(
                info.position,
                Quaternion.Euler(0, 0, info.rotation),
                new Vector3(info.scale.x, info.scale.y, 1)
            );

            // 应用变换矩阵
            GL.MultMatrix(transformMatrix);

            blitMaterial.mainTexture = info.texture;
            blitMaterial.SetPass(0);

            GL.Begin(GL.QUADS);
            float w = info.texture.width / 2f;
            float h = info.texture.height / 2f;

            GL.TexCoord2(0, 0); GL.Vertex3(-w, -h, 0);
            GL.TexCoord2(1, 0); GL.Vertex3(w, -h, 0);
            GL.TexCoord2(1, 1); GL.Vertex3(w, h, 0);
            GL.TexCoord2(0, 1); GL.Vertex3(-w, h, 0);

            GL.End();
            GL.PopMatrix();
        }

        GL.PopMatrix();

        // 读取结果
        Texture2D result = new Texture2D(width, height);
        result.ReadPixels(new Rect(0, 0, width, height), 0, 0);
        result.Apply();

        RenderTexture.ReleaseTemporary(rt);
        RenderTexture.active = null;
        Destroy(blitMaterial);

        return result;
    }


}