// 启用模板测试
glEnable(GL_STENCIL_TEST);

// 配置模板测试
glStencilFunc(
    GL_ALWAYS,    // 测试函数：总是通过
    1,            // 参考值
    0xFF          // 掩码
);

// 配置模板操作
glStencilOp(
    GL_KEEP,      // 测试失败：保持原值
    GL_KEEP,      // 测试通过，深度失败：保持原值
    GL_REPLACE    // 都通过：写入参考值
);

// 渲染流程：
// 1. 正常绘制物体，写入模板缓冲
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_ALWAYS, 1, 0xFF);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
glStencilMask(0xFF);       // 允许写入模板缓冲
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

drawObject();  // 正常绘制物体

// 2. 绘制放大版物体，只在模板值 != 1 的区域绘制（描边）
glStencilFunc(GL_NOTEQUAL, 1, 0xFF);
glStencilMask(0x00);       // 禁止写入模板缓冲
glDisable(GL_DEPTH_TEST);  // 禁用深度测试，确保描边可见

outlineShader.use();
float scale = 1.1f;  // 放大 10%
glm::mat4 model = glm::scale(originalModel, glm::vec3(scale));
outlineShader.setMat4("model", model);
drawObject();

glStencilMask(0xFF);
glStencilFunc(GL_ALWAYS, 0, 0xFF);
glEnable(GL_DEPTH_TEST);
glDisable(GL_STENCIL_TEST);

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

// 1. 先渲染所有不透明物体
glDisable(GL_BLEND);
for (auto& obj : opaqueObjects) {
    renderObject(obj);
}

// 2. 排序半透明物体（按距离相机远近）
std::sort(transparentObjects.begin(), transparentObjects.end(),
    [&](const auto& a, const auto& b) {
        return glm::length(cameraPos - a.pos) > glm::length(cameraPos - b.pos);
    });

// 3. 从后往前渲染
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
for (auto& obj : transparentObjects) {
    renderObject(obj);
}

// 加法混合：颜色叠加（火焰、光晕）
glBlendFunc(GL_SRC_ALPHA, GL_ONE);

glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);      // 剔除背面（默认）
glFrontFace(GL_CCW);      // 逆时针为正面（默认）

// ===== 1. 创建帧缓冲 =====
unsigned int fbo;
glGenFramebuffers(1, &fbo);
glBindFramebuffer(GL_FRAMEBUFFER, fbo);

// ===== 2. 创建颜色附件（纹理） =====
unsigned int colorTexture;
glGenTextures(1, &colorTexture);
glBindTexture(GL_TEXTURE_2D, colorTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 800, 600, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTexture, 0);

// ===== 3. 创建深度/模板附件（渲染缓冲对象） =====
unsigned int rbo;
glGenRenderbuffers(1, &rbo);
glBindRenderbuffer(GL_RENDERBUFFER, rbo);
glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 800, 600);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, rbo);

// ===== 4. 检查完整性 =====
if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
    std::cerr << "Framebuffer not complete!" << std::endl;
}
glBindFramebuffer(GL_FRAMEBUFFER, 0);

// 第一遍：渲染到 FBO
glBindFramebuffer(GL_FRAMEBUFFER, fbo);
glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);

sceneShader.use();
renderScene(sceneShader);

// 第二遍：使用 FBO 的颜色纹理进行后处理
glBindFramebuffer(GL_FRAMEBUFFER, 0);  // 切回默认帧缓冲
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);

postProcessShader.use();
glBindTexture(GL_TEXTURE_2D, colorTexture);
renderFullscreenQuad();

float quadVertices[] = {
    // 位置          // UV
    -1.0f,  1.0f,   0.0f, 1.0f,
    -1.0f, -1.0f,   0.0f, 0.0f,
     1.0f, -1.0f,   1.0f, 0.0f,

    -1.0f,  1.0f,   0.0f, 1.0f,
     1.0f, -1.0f,   1.0f, 0.0f,
     1.0f,  1.0f,   1.0f, 1.0f,
};

#version 460 core
in vec2 vTexCoord;
out vec4 FragColor;
uniform sampler2D screenTexture;

void main() {
    FragColor = vec4(vec3(1.0 - texture(screenTexture, vTexCoord)), 1.0);
}

void main() {
    vec4 color = texture(screenTexture, vTexCoord);
    float gray = dot(color.rgb, vec3(0.299, 0.587, 0.114));
    FragColor = vec4(vec3(gray), 1.0);
}

void main() {
    float offset = 1.0 / 300.0;
    vec2 offsets[9] = vec2[](
        vec2(-offset,  offset), vec2(0.0,  offset), vec2(offset,  offset),
        vec2(-offset,  0.0),    vec2(0.0,  0.0),    vec2(offset,  0.0),
        vec2(-offset, -offset), vec2(0.0, -offset), vec2(offset, -offset)
    );

    // 边缘检测核
    float kernel[9] = float[](
        -1, -1, -1,
        -1,  8, -1,
        -1, -1, -1
    );

    vec3 result = vec3(0.0);
    for (int i = 0; i < 9; i++) {
        result += texture(screenTexture, vTexCoord + offsets[i]).rgb * kernel[i];
    }
    FragColor = vec4(result, 1.0);
}