package com.chuangzhou.vivid2D.render;

import com.chuangzhou.vivid2D.render.model.Model2D;
import com.chuangzhou.vivid2D.render.model.ModelPart;
import com.chuangzhou.vivid2D.render.systems.buffer.BufferBuilder;
import com.chuangzhou.vivid2D.render.systems.buffer.Tesselator;
import com.chuangzhou.vivid2D.render.model.util.LightSource;
import com.chuangzhou.vivid2D.render.model.util.Mesh2D;
import com.chuangzhou.vivid2D.render.model.util.PhysicsSystem;
import com.chuangzhou.vivid2D.render.systems.RenderSystem;
import com.chuangzhou.vivid2D.render.systems.ShaderSources;
import org.joml.Matrix3f;
import org.joml.Vector2f;
import org.joml.Vector4f;
import org.lwjgl.opengl.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;

import static org.lwjgl.opengl.GL20.glGetUniformLocation;

/**
 * vivid2D 模型完整渲染系统
 *
 * <p>该系统提供了完整的 vivid2D 模型加载、渲染和显示功能，支持多种渲染模式和效果：</p>
 *
 * <ul>
 *   <li>基础模型渲染</li>
 *   <li>光照效果渲染</li>
 *   <li>纹理贴图渲染</li>
 *   <li>模型加载与解析</li>
 * </ul>
 *
 * <h3>使用示例：</h3>
 * <ul>
 *   <li>{@link com.chuangzhou.vivid2D.test.ModelLoadTest} - 模型加载测试</li>
 *   <li>{@link com.chuangzhou.vivid2D.test.ModelRenderLightingTest} - 光照渲染测试</li>
 *   <li>{@link com.chuangzhou.vivid2D.test.ModelRenderTest} - 基础渲染测试</li>
 *   <li>{@link com.chuangzhou.vivid2D.test.ModelRenderTest2} - 进阶渲染测试</li>
 *   <li>{@link com.chuangzhou.vivid2D.test.ModelRenderTextureTest} - 纹理渲染测试</li>
 *   <li>{@link com.chuangzhou.vivid2D.test.ModelTest} - 基础模型测试</li>
 *   <li>{@link com.chuangzhou.vivid2D.test.ModelTest2} - 进阶模型测试</li>
 * </ul>
 *
 * @author tzdwindows
 * @version 1.2
 * @since 2025-10-13
 */
public final class ModelRender {
    /**
     * 渲染系统日志记录器，用于记录渲染过程中的调试信息、错误和性能数据
     */
    private static final Logger logger = LoggerFactory.getLogger(ModelRender.class);

    /**
     * 私有构造函数，防止外部实例化 - 这是一个工具类，只包含静态方法
     */
    private ModelRender() { /* no instances */ }

// ================== 全局状态 ==================

    /**
     * 渲染系统初始化状态标志，确保系统只初始化一次
     * @see #initialize()
     * @see #isInitialized()
     */
    private static boolean initialized = false;

    /**
     * 视口宽度（像素），定义渲染区域的大小
     * 默认值：800像素
     * @see #setViewport(int, int)
     */
    private static int viewportWidth = 800;

    /**
     * 视口高度（像素），定义渲染区域的大小
     * 默认值：600像素
     * @see #setViewport(int, int)
     */
    private static int viewportHeight = 600;

    /**
     * 清除颜色（RGBA），用于在每帧开始时清空颜色缓冲区
     * 默认值：黑色不透明 (0.0f, 0.0f, 0.0f, 1.0f)
     * @see RenderSystem#clearColor(float, float, float, float)
     */
    private static final Vector4f CLEAR_COLOR = new Vector4f(0.0f, 0.0f, 0.0f, 1.0f);

    /**
     * 深度测试启用标志，控制是否进行深度缓冲测试
     * 在2D渲染中通常禁用以提高性能
     * 默认值：false（禁用）
     * @see RenderSystem#enableDepthTest()
     * @see RenderSystem#disableDepthTest()
     */
    private static final boolean enableDepthTest = false;

    /**
     * 混合功能启用标志，控制透明度和颜色混合
     * 默认值：true（启用）
     * @see RenderSystem#enableBlend()
     * @see RenderSystem#disableBlend()
     */
    private static final boolean enableBlending = true;

    private static final int SHADER_MAX_LIGHTS = 8;

// ================== 着色器与资源管理 ==================

    /**
     * 着色器程序缓存映射，按名称存储已编译的着色器程序
     * 键：着色器名称（如 "default"）
     * 值：对应的着色器程序对象
     * @see ShaderSources.ShaderProgram
     */
    private static final Map<String, ShaderSources.ShaderProgram> shaderMap = new HashMap<>();

    /**
     * 默认着色器程序，用于大多数模型的渲染
     * 包含基础的光照、纹理和变换功能
     * @see #compileDefaultShader()
     */
    private static ShaderSources.ShaderProgram defaultProgram = null;

    /**
     * 网格GPU资源缓存，管理已上传到GPU的网格数据
     * 键：Mesh2D对象
     * 值：对应的OpenGL资源（VAO、VBO、EBO）
     * @see MeshGLResources
     */
    private static final Map<Mesh2D, MeshGLResources> meshResources = new HashMap<>();

    /**
     * 纹理单元分配器，用于管理多个纹理的绑定
     * 确保不同的纹理绑定到正确的纹理单元
     * 默认从0开始递增分配
     */
    private static final AtomicInteger textureUnitAllocator = new AtomicInteger(0);

    /**
     * 默认白色纹理ID，当模型没有指定纹理时使用
     * 这是一个1x1的纯白色纹理，确保模型有基本的颜色显示
     * @see #createDefaultTexture()
     */
    private static int defaultTextureId = 0;

// ================== 碰撞箱渲染配置 ==================

    /**
     * 碰撞箱渲染开关，控制是否在场景中显示物理碰撞体的轮廓
     * 调试时非常有用，可以直观看到碰撞边界
     * 默认值：true（启用）
     */
    public static boolean renderColliders = true;

    /**
     * 碰撞箱线框宽度，控制碰撞体轮廓线的粗细
     * 单位：像素
     * 默认值：1.0f
     */
    public static float colliderLineWidth = 1.0f;

    /**
     * 碰撞箱颜色（RGBA），定义碰撞体轮廓的显示颜色
     * 默认值：白色不透明 (1.0f, 1.0f, 1.0f, 1.0f)
     */
    public static Vector4f colliderColor = new Vector4f(1.0f, 1.0f, 1.0f, 1.0f);

    /**
     * 圆形碰撞体细分数量，控制圆形碰撞体的平滑度
     * 值越高圆形越平滑，但渲染开销也越大
     * 默认值：32（在性能和视觉效果间取得平衡）
     */
    private static final int CIRCLE_SEGMENTS = 32;

    /**
     * 光源位置渲染开关，控制是否在场景中显示光源的位置
     * 用点状标记显示每个启用的光源位置
     * 默认值：true（启用）
     */
    public static boolean renderLightPositions = true;

    // ================== 内部类：ShaderSources.ShaderProgram ==================


    // ================== 内部类：MeshGLResources ==================
    private static class MeshGLResources {
        int vao = 0;
        int vbo = 0;
        int ebo = 0;
        boolean initialized = false;

        void dispose() {
            if (ebo != 0) { GL15.glDeleteBuffers(ebo); ebo = 0; }
            if (vbo != 0) { GL15.glDeleteBuffers(vbo); vbo = 0; }
            if (vao != 0) { GL30.glDeleteVertexArrays(vao); vao = 0; }
            initialized = false;
        }
    }

    // ================== 初始化 / 清理 ==================
    public static synchronized void initialize() {
        if (initialized) return;

        logger.info("Initializing ModelRender...");

        // 初始化渲染系统
        RenderSystem.beginInitialization();
        RenderSystem.initRenderThread();

        logGLInfo();
        setupGLState();

        try {
            compileDefaultShader();
        } catch (RuntimeException ex) {
            logger.error("Failed to compile default shader: {}", ex.getMessage());
            throw ex;
        }

        createDefaultTexture();
        RenderSystem.viewport(0, 0, viewportWidth, viewportHeight);
        RenderSystem.finishInitialization();

        initialized = true;
        logger.info("ModelRender initialized successfully");
    }

    private static void logGLInfo() {
        logger.info("OpenGL Vendor: {}", RenderSystem.getVendor());
        logger.info("OpenGL Renderer: {}", RenderSystem.getRenderer());
        logger.info("OpenGL Version: {}", RenderSystem.getOpenGLVersion());
        logger.info("GLSL Version: {}", RenderSystem.getGLSLVersion());
        RenderSystem.logDetailedGLInfo();
    }


    private static void uploadLightsToShader(ShaderSources.ShaderProgram sp, Model2D model) {
        List<com.chuangzhou.vivid2D.render.model.util.LightSource> lights = model.getLights();
        int idx = 0;

        // 只上传已启用的光源，最多 MAX_LIGHTS（8）
        for (int i = 0; i < lights.size() && idx < 8; i++) {
            com.chuangzhou.vivid2D.render.model.util.LightSource l = lights.get(i);
            if (!l.isEnabled()) continue;

            // 基础属性
            setUniformVec2Internal(sp, "uLightsPos[" + idx + "]", l.isAmbient() ? new org.joml.Vector2f(0f, 0f) : l.getPosition());
            setUniformVec3Internal(sp, "uLightsColor[" + idx + "]", l.getColor());
            setUniformFloatInternal(sp, "uLightsIntensity[" + idx + "]", l.getIntensity());
            setUniformIntInternal(sp, "uLightsIsAmbient[" + idx + "]", l.isAmbient() ? 1 : 0);

            // 辉光相关（如果没有被设置也安全地上传默认值）
            setUniformIntInternal(sp, "uLightsIsGlow[" + idx + "]", l.isGlow() ? 1 : 0);
            setUniformVec2Internal(sp, "uLightsGlowDir[" + idx + "]", l.getGlowDirection() != null ? l.getGlowDirection() : new org.joml.Vector2f(0f, 0f));
            setUniformFloatInternal(sp, "uLightsGlowIntensity[" + idx + "]", l.getGlowIntensity());
            setUniformFloatInternal(sp, "uLightsGlowRadius[" + idx + "]", l.getGlowRadius());
            setUniformFloatInternal(sp, "uLightsGlowAmount[" + idx + "]", l.getGlowAmount());

            idx++;
        }

        // 上传实际有效光源数量
        setUniformIntInternal(sp, "uLightCount", idx);

        // 禁用剩余槽位（确保 shader 中不会读取到垃圾值）
        for (int i = idx; i < 8; i++) {
            setUniformFloatInternal(sp, "uLightsIntensity[" + i + "]", 0f);
            setUniformIntInternal(sp, "uLightsIsAmbient[" + i + "]", 0);
            setUniformVec3Internal(sp, "uLightsColor[" + i + "]", new org.joml.Vector3f(0f, 0f, 0f));
            setUniformVec2Internal(sp, "uLightsPos[" + i + "]", new org.joml.Vector2f(0f, 0f));

            // 关闭辉光槽
            setUniformIntInternal(sp, "uLightsIsGlow[" + i + "]", 0);
            setUniformVec2Internal(sp, "uLightsGlowDir[" + i + "]", new org.joml.Vector2f(0f, 0f));
            setUniformFloatInternal(sp, "uLightsGlowIntensity[" + i + "]", 0f);
            setUniformFloatInternal(sp, "uLightsGlowRadius[" + i + "]", 0f);
            setUniformFloatInternal(sp, "uLightsGlowAmount[" + i + "]", 0f);
        }
    }


    private static void setupGLState() {
        RenderSystem.clearColor(CLEAR_COLOR.x, CLEAR_COLOR.y, CLEAR_COLOR.z, CLEAR_COLOR.w);

        if (enableBlending) {
            RenderSystem.enableBlend();
            RenderSystem.blendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
        } else {
            RenderSystem.disableBlend();
        }

        if (enableDepthTest) {
            RenderSystem.enableDepthTest();
            RenderSystem.depthFunc(GL11.GL_LEQUAL);
            RenderSystem.depthMask(true);
            RenderSystem.clearDepth(1.0);
        } else {
            RenderSystem.disableDepthTest();
        }

        RenderSystem.checkGLError("setupGLState");
    }

    private static void compileDefaultShader() {
        int vs = compileShader(GL20.GL_VERTEX_SHADER, ShaderSources.VERTEX_SHADER_SRC);
        int fs = compileShader(GL20.GL_FRAGMENT_SHADER, ShaderSources.FRAGMENT_SHADER_SRC);
        int prog = linkProgram(vs, fs);
        ShaderSources.ShaderProgram sp = new ShaderSources.ShaderProgram(prog);
        shaderMap.put("default", sp);
        defaultProgram = sp;

        sp.use();
        setUniformIntInternal(sp, "uTexture", 0);
        setUniformFloatInternal(sp, "uOpacity", 1.0f);
        setUniformVec4Internal(sp, "uColor", new Vector4f(1,1,1,1));
        setUniformIntInternal(sp, "uBlendMode", 0);
        setUniformIntInternal(sp, "uDebugMode", 0);
        setUniformIntInternal(sp, "uLightCount", 0); // 默认没有光源
        sp.stop();
    }

    private static int compileShader(int type, String src) {
        RenderSystem.assertOnRenderThread();
        return RenderSystem.compileShader(type, src);
    }

    private static int linkProgram(int vs, int fs) {
        RenderSystem.assertOnRenderThread();
        return RenderSystem.linkProgram(vs, fs);
    }

    private static void createDefaultTexture() {
        RenderSystem.assertOnRenderThread();
        defaultTextureId = RenderSystem.createDefaultTexture();
        RenderSystem.checkGLError("createDefaultTexture");
    }

    public static synchronized void cleanup() {
        if (!initialized) return;

        logger.info("Cleaning up ModelRender...");

        // mesh resources
        for (MeshGLResources r : meshResources.values()) r.dispose();
        meshResources.clear();

        // shaders
        for (ShaderSources.ShaderProgram sp : shaderMap.values()) sp.delete();
        shaderMap.clear();
        defaultProgram = null;

        // textures
        if (defaultTextureId != 0) {
            RenderSystem.deleteTextures(defaultTextureId);
            defaultTextureId = 0;
        }

        initialized = false;
        logger.info("ModelRender cleaned up");
    }

    // ================== 渲染流程 (已修改) ==================
    public static void render(float deltaTime, Model2D model) {
        if (!initialized) throw new IllegalStateException("ModelRender not initialized");
        if (model == null) return;

        // 确保在渲染线程
        RenderSystem.assertOnRenderThread();

        // 添加前置错误检查
        RenderSystem.checkGLError("render_start");

        // 物理系统更新
        PhysicsSystem physics = model.getPhysics();
        if (physics != null && physics.isEnabled()) {
            physics.update(deltaTime, model);
        }

        model.update(deltaTime);

        // 检查清除操作前的状态
        RenderSystem.checkGLError("before_clear");
        RenderSystem.clear(GL11.GL_COLOR_BUFFER_BIT | (enableDepthTest ? GL11.GL_DEPTH_BUFFER_BIT : 0));
        RenderSystem.checkGLError("after_clear");

        // 检查着色器程序
        if (defaultProgram == null || defaultProgram.programId == 0) {
            logger.error("Default shader program is not initialized");
            return;
        }

        defaultProgram.use();
        RenderSystem.checkGLError("after_use_program");

        // 设置投影与视图
        Matrix3f proj = buildOrthoProjection(viewportWidth, viewportHeight);
        setUniformMatrix3(defaultProgram, "uProjectionMatrix", proj);
        setUniformMatrix3(defaultProgram, "uViewMatrix", new Matrix3f().identity());
        RenderSystem.checkGLError("after_set_matrices");

        // 添加光源数据上传
        uploadLightsToShader(defaultProgram, model);
        RenderSystem.checkGLError("after_upload_lights");

        // 在渲染光源位置前检查
        RenderSystem.checkGLError("before_render_light_positions");
        renderLightPositions(model);
        RenderSystem.checkGLError("after_render_light_positions");

        // 递归渲染所有根部件
        Matrix3f identity = new Matrix3f().identity();
        for (ModelPart p : model.getParts()) {
            if (p.getParent() != null) continue;
            renderPartRecursive(p, identity);
        }
        RenderSystem.checkGLError("after_render_parts");

        if (renderColliders && physics != null) {
            renderPhysicsColliders(physics);
            RenderSystem.checkGLError("after_render_colliders");
        }

        defaultProgram.stop();
        RenderSystem.checkGLError("render_end");
    }

    private static void renderLightPositions(Model2D model) {
        if (!renderLightPositions) return;
        // 设置灯泡颜色为光源的颜色
        for (LightSource light : model.getLights()) {
            if (!light.isEnabled()) continue;

            // 使用光源的颜色来绘制灯泡
            Vector4f lightColor = new Vector4f(light.getColor().x, light.getColor().y, light.getColor().z, 1.0f);
            setUniformVec4Internal(defaultProgram, "uColor", lightColor);

            // 绘制灯泡形状
            drawLightBulb(light.getPosition(), light.getIntensity());

            if (light.isAmbient()) {
                drawCrossMark(light.getPosition(), light.getIntensity());
            }
        }
        // 恢复原始颜色
        setUniformVec4Internal(defaultProgram, "uColor", new Vector4f(1,1,1,1));
    }

    /**
     * 绘制简洁的灯泡形状
     * @param position 灯泡位置
     * @param intensity 光源强度，用于控制灯泡大小
     */
    private static void drawLightBulb(Vector2f position, float intensity) {
        Tesselator tesselator = Tesselator.getInstance();
        BufferBuilder builder = tesselator.getBuilder();
        float bulbSize = 3.0f + (intensity / 10.0f);
        int segments = 16;
        builder.begin(RenderSystem.DRAW_TRIANGLE_FAN, segments + 2);

        builder.vertex(position.x, position.y, 0.5f, 0.5f);

        for (int i = 0; i <= segments; i++) {
            double angle = 2.0 * Math.PI * i / segments;
            float x = position.x + bulbSize * (float) Math.cos(angle);
            float y = position.y + bulbSize * (float) Math.sin(angle);
            builder.vertex(x, y, 0.5f, 0.5f);
        }
        tesselator.end();
    }

    /**
     * 绘制十字标记（用于环境光）
     */
    private static void drawCrossMark(Vector2f position, float size) {
        Tesselator tesselator = Tesselator.getInstance();
        BufferBuilder builder = tesselator.getBuilder();

        float crossSize = size * 0.8f;

        // 绘制水平线
        builder.begin(RenderSystem.DRAW_LINES, 2);
        builder.vertex(position.x - crossSize, position.y, 0.5f, 0.5f);
        builder.vertex(position.x + crossSize, position.y, 0.5f, 0.5f);
        tesselator.end();

        // 绘制垂直线
        builder.begin(RenderSystem.DRAW_LINES, 2);
        builder.vertex(position.x, position.y - crossSize, 0.5f, 0.5f);
        builder.vertex(position.x, position.y + crossSize, 0.5f, 0.5f);
        tesselator.end();
    }

    /**
     * 关键修改点：在渲染前确保更新 part 的 worldTransform，
     * 然后直接使用 part.getWorldTransform() 作为 uModelMatrix 传入 shader。
     */
    private static void renderPartRecursive(ModelPart part, Matrix3f parentMat) {
        // 确保 part 的 local/world 矩阵被计算（会更新 transformDirty）
        part.updateWorldTransform(parentMat, false);

        // 直接使用已经计算好的 worldTransform
        Matrix3f world = part.getWorldTransform();

        // 先设置部件相关的 uniform（opacity / blendMode / color 等）
        setPartUniforms(defaultProgram, part);

        // 把 world 矩阵传给 shader（uModelMatrix）
        setUniformMatrix3(defaultProgram, "uModelMatrix", world);

        // 绘制本节点的所有 mesh（将 world 传入 renderMesh）
        for (Mesh2D mesh : part.getMeshes()) {
            renderMesh(mesh, world);
        }

        // 递归渲染子节点，继续传入当前 world 作为子节点的 parent
        for (ModelPart child : part.getChildren()) {
            renderPartRecursive(child, world);
        }
    }

    private static void renderMesh(Mesh2D mesh, Matrix3f modelMatrix) {
        if (!mesh.isVisible()) return;

        // 如果 mesh 已经被烘焙到世界坐标，则传 identity 矩阵给 shader（防止重复变换）
        Matrix3f matToUse = mesh.isBakedToWorld() ? new Matrix3f().identity() : modelMatrix;

        // 设置纹理相关的uniform
        if (mesh.getTexture() != null) {
            mesh.getTexture().bind(0); // 绑定到纹理单元0
            setUniformIntInternal(defaultProgram, "uTexture", 0);
        } else {
            // 使用默认白色纹理
            RenderSystem.bindTexture(defaultTextureId);
            setUniformIntInternal(defaultProgram, "uTexture", 0);
        }

        // 将模型矩阵设置为当前 mesh 使用的矩阵（shader 内名为 uModelMatrix）
        setUniformMatrix3(defaultProgram, "uModelMatrix", matToUse);

        // 调用 Mesh2D 的 draw 方法，传入当前使用的着色器程序和变换矩阵
        mesh.draw(defaultProgram.programId, matToUse);

        RenderSystem.checkGLError("renderMesh");
    }

    // ================== 渲染碰撞箱相关实现 ==================

    private static void renderPhysicsColliders(PhysicsSystem physics) {
        if (physics == null) {
            logger.warn("renderPhysicsColliders: physics system is null");
            return;
        }

        // 设置渲染状态
        RenderSystem.checkGLError("before_set_line_width");
        RenderSystem.lineWidth(colliderLineWidth);
        RenderSystem.checkGLError("after_set_line_width");

        RenderSystem.activeTexture(RenderSystem.GL_TEXTURE0);
        RenderSystem.bindTexture(defaultTextureId);
        RenderSystem.checkGLError("after_bind_texture");

        setUniformIntInternal(defaultProgram, "uTexture", 0);
        setUniformVec4Internal(defaultProgram, "uColor", colliderColor);
        setUniformFloatInternal(defaultProgram, "uOpacity", 1.0f);
        setUniformIntInternal(defaultProgram, "uBlendMode", 0);
        setUniformIntInternal(defaultProgram, "uDebugMode", 0);
        RenderSystem.checkGLError("after_set_uniforms");

        // 使用单位矩阵作为 model（碰撞体顶点按世界坐标提供）
        setUniformMatrix3(defaultProgram, "uModelMatrix", new Matrix3f().identity());
        RenderSystem.checkGLError("after_set_model_matrix");

        List<PhysicsSystem.PhysicsCollider> colliders = physics.getColliders();
        if (colliders == null || colliders.isEmpty()) {
            logger.debug("No colliders to render");
            return;
        }

        int enabledColliders = 0;
        for (PhysicsSystem.PhysicsCollider collider : colliders) {
            if (collider == null || !collider.isEnabled()) continue;

            RenderSystem.checkGLError("before_render_collider_" + enabledColliders);

            if (collider instanceof PhysicsSystem.CircleCollider) {
                PhysicsSystem.CircleCollider c = (PhysicsSystem.CircleCollider) collider;
                if (c.getCenter() != null && c.getRadius() > 0) {
                    drawCircleColliderWire(c.getCenter(), c.getRadius());
                    enabledColliders++;
                } else {
                    logger.warn("Invalid CircleCollider: center={}, radius={}", c.getCenter(), c.getRadius());
                }
            } else if (collider instanceof PhysicsSystem.RectangleCollider) {
                PhysicsSystem.RectangleCollider r = (PhysicsSystem.RectangleCollider) collider;
                if (r.getCenter() != null && r.getWidth() > 0 && r.getHeight() > 0) {
                    drawRectangleColliderWire(r.getCenter(), r.getWidth(), r.getHeight());
                    enabledColliders++;
                } else {
                    logger.warn("Invalid RectangleCollider: center={}, width={}, height={}",
                            r.getCenter(), r.getWidth(), r.getHeight());
                }
            } else {
                logger.warn("Unknown collider type: {}", collider.getClass().getSimpleName());
            }

            RenderSystem.checkGLError("after_render_collider_" + enabledColliders);
        }

        logger.debug("Rendered {} enabled colliders", enabledColliders);

        // 恢复默认线宽
        RenderSystem.lineWidth(1.0f);
        RenderSystem.checkGLError("after_reset_line_width");
    }


    /**
     * 绘制圆形碰撞框（线框）
     * 使用临时 VAO/VBO，每帧创建并删除（简单实现）
     */
    private static void drawCircleColliderWire(Vector2f center, float radius) {
        int segments = Math.max(8, CIRCLE_SEGMENTS);

        Tesselator tesselator = Tesselator.getInstance();
        BufferBuilder builder = tesselator.getBuilder();

        builder.begin(RenderSystem.DRAW_LINE_LOOP, segments);
        for (int i = 0; i < segments; i++) {
            double ang = 2.0 * Math.PI * i / segments;
            float x = center.x + radius * (float) Math.cos(ang);
            float y = center.y + radius * (float) Math.sin(ang);
            builder.vertex(x, y, 0.5f, 0.5f);
        }
        tesselator.end();
    }

    /**
     * 绘制矩形碰撞框（线框）
     */
    private static void drawRectangleColliderWire(Vector2f center, float width, float height) {
        float halfW = width / 2.0f;
        float halfH = height / 2.0f;

        Tesselator tesselator = Tesselator.getInstance();
        BufferBuilder builder = tesselator.getBuilder();

        builder.begin(RenderSystem.DRAW_LINE_LOOP, 4);
        builder.vertex(center.x - halfW, center.y - halfH, 0.5f, 0.5f);
        builder.vertex(center.x + halfW, center.y - halfH, 0.5f, 0.5f);
        builder.vertex(center.x + halfW, center.y + halfH, 0.5f, 0.5f);
        builder.vertex(center.x - halfW, center.y + halfH, 0.5f, 0.5f);
        tesselator.end();
    }

    // ================== uniform 设置辅助（内部使用，确保 program 已绑定） ==================
    private static void setUniformIntInternal(ShaderSources.ShaderProgram sp, String name, int value) {
        int loc = sp.getUniformLocation(name);
        if (loc != -1) RenderSystem.uniform1i(loc, value);
    }

    private static void setUniformVec3Internal(ShaderSources.ShaderProgram sp, String name, org.joml.Vector3f vec) {
        int loc = sp.getUniformLocation(name);
        if (loc != -1) RenderSystem.uniform3f(loc, vec);
    }

    private static void setUniformVec2Internal(ShaderSources.ShaderProgram sp, String name, org.joml.Vector2f vec) {
        int loc = sp.getUniformLocation(name);
        if (loc != -1) RenderSystem.uniform2f(loc, vec);
    }

    private static void setUniformFloatInternal(ShaderSources.ShaderProgram sp, String name, float value) {
        int loc = sp.getUniformLocation(name);
        if (loc != -1) RenderSystem.uniform1f(loc, value);
    }

    private static void setUniformVec4Internal(ShaderSources.ShaderProgram sp, String name, org.joml.Vector4f vec) {
        int loc = sp.getUniformLocation(name);
        if (loc != -1) RenderSystem.uniform4f(loc, vec);
    }

    private static void setUniformMatrix3(ShaderSources.ShaderProgram sp, String name, org.joml.Matrix3f m) {
        int loc = sp.getUniformLocation(name);
        if (loc == -1) return;
        RenderSystem.uniformMatrix3(loc, m);
    }

    // ================== 部件属性 ==================
    private static void setPartUniforms(ShaderSources.ShaderProgram sp, ModelPart part) {
        setUniformFloatInternal(sp, "uOpacity", part.getOpacity());
        int blend = 0;
        ModelPart.BlendMode bm = part.getBlendMode();
        if (bm != null) {
            switch (bm) {
                case ADDITIVE: blend = 1; break;
                case MULTIPLY: blend = 2; break;
                case SCREEN: blend = 3; break;
                case NORMAL: default: blend = 0;
            }
        } else {
            blend = 0;
        }
        setUniformIntInternal(sp, "uBlendMode", blend);
        // 这里保留为白色，若需要部件 tint 请替换为 part 的 color 属性
        setUniformVec4Internal(sp, "uColor", new Vector4f(1,1,1,1));
    }

    // ================== 工具 ==================
    private static Matrix3f buildOrthoProjection(int width, int height) {
        Matrix3f m = new Matrix3f();
        m.set(
                2.0f / width, 0.0f, -1.0f,
                0.0f, -2.0f / height, 1.0f,
                0.0f, 0.0f, 1.0f
        );
        return m;
    }

    public static void setViewport(int width, int height) {
        viewportWidth = Math.max(1, width);
        viewportHeight = Math.max(1, height);
        RenderSystem.viewport(0, 0, viewportWidth, viewportHeight);
    }

    // ================== 辅助：外部获取状态 ==================
    public static boolean isInitialized() { return initialized; }
    public static int getLoadedMeshCount() { return meshResources.size(); }

}