完成第二次回家作业(第三课: 绘制3D OpenCV 图标)

src/Game.cpp

@@ -37,6 +37,11 @@ void Game::initialize() {
     CHECK_GL(glCullFace(GL_BACK));
     CHECK_GL(glFrontFace(GL_CCW));
 
+    CHECK_GL(glEnable(GL_LIGHTING));         // 启用固定管线光照 (古代特性)
+    CHECK_GL(glEnable(GL_LIGHT0));           // 启用 0 号光源 (古代特性)
+    CHECK_GL(glEnable(GL_COLOR_MATERIAL));   // 启用材质颜色追踪 (古代特性)
+    CHECK_GL(glEnable(GL_NORMALIZE));        // 法线归一化
+
     // glm::vec4 lightPos(-1, 1, 1, 0); // 等会用更现代的方式指定光源方向
 
     auto program = GLProgram().make();
@@ -52,30 +57,96 @@ void Game::initialize() {
     CHECK_GL(glLinkProgram(program));
     m_private->program = std::move(program);
 
-    m_private->obj.load_obj(OPENGLTUTOR_HOME "assets/monkey.obj");
+    m_private->obj.load_obj(OPENGLTUTOR_HOME "assets/opencvpart.obj");
     m_private->obj.draw_obj(m_private->drawableObj, /*dynamic=*/false);
 }
 
-void Game::render() {
-    int width, height;
-    glfwGetWindowSize(m_window, &width, &height);
-    CHECK_GL(glViewport(0, 0, width, height));
-
-    CHECK_GL(glClearColor(0.0f, 0.0f, 0.0f, 0.0f));
-    CHECK_GL(glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT));
+// 手动计算法线 asin 系数
+static glm::vec3 compute_normal_biased(glm::vec3 a, glm::vec3 b, glm::vec3 c) noexcept {
+    auto ab = b - a;
+    auto ac = c - a;
+    auto n = glm::cross(ab, ac);
+    auto nLen = glm::length(n);
+    if (nLen != 0) {
+        n *= glm::asin(nLen / (glm::length(ab) * glm::length(ac))) / nLen;
+    }
+    return n;
+}
 
+void Game::render() {
+    CHECK_GL(glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)); // 清空画布
+
+    // 存储各个角度
+    static auto models = [] {
+        float k = 0.618f;
+        float xDown = k * std::sqrt(3.f);
+        float hOpencv = k * 1.f;
+        std::vector<glm::mat4x4> res;
+        glm::mat4x4 model{1.f};
+        model = glm::translate(model, glm::vec3{hOpencv * 2, 0, 0});
+        model = glm::rotate(model, glm::radians(60.f), glm::vec3{0, 1, 0});
+        res.push_back(model);
+
+        model = glm::mat4x4{1.f};
+        model = glm::translate(model, glm::vec3{-hOpencv, 0, -xDown});
+        model = glm::rotate(model, glm::radians(180.f), glm::vec3{0, 1, 0});
+        res.push_back(model);
+
+        model = glm::mat4x4{1.f};
+        model = glm::translate(model, glm::vec3{-hOpencv, 0, xDown});
+        model = glm::rotate(model, glm::radians(240.f), glm::vec3{0, 1, 0});
+        res.push_back(model);
+        return res;
+    }();
+
+    auto& vertices = m_private->obj.vertices;
+    auto& faces = m_private->obj.faces;
+
+    // 计算平滑渲染需要的法线
+    static auto normals = [&] {
+        std::vector<glm::vec3> res;
+        res.resize(faces.size());
+        for (auto const& v : faces) {
+            auto a = vertices[v[0]].position,
+                 b = vertices[v[1]].position,
+                 c = vertices[v[2]].position;
+            for (std::size_t i = 0; i < 3; ++i)
+                res[v[i]] += compute_normal_biased(a, b, c);
+        }
+        for (auto& it : res)
+            it = glm::normalize(it);
+        return res;
+    }();
+
+    std::size_t i = 1;
     auto projection = m_inputCtl.get_projection_matrix();
     auto view = m_inputCtl.get_view_matrix();
-    glm::mat4x4 model(1.0f);
-
-    CHECK_GL(glUseProgram(m_private->program));
-    CHECK_GL(glUniformMatrix4fv(glGetUniformLocation(m_private->program, "uniModel"), 1, GL_FALSE, glm::value_ptr(model)));
-    CHECK_GL(glUniformMatrix4fv(glGetUniformLocation(m_private->program, "uniView"), 1, GL_FALSE, glm::value_ptr(view)));
-    CHECK_GL(glUniformMatrix4fv(glGetUniformLocation(m_private->program, "uniProjection"), 1, GL_FALSE, glm::value_ptr(projection)));
-
-    glm::vec2 mousePos = m_inputCtl.get_cursor_pos();
-    glm::vec3 lightDir = glm::normalize(glm::vec3(mousePos.x, mousePos.y, 1));
-    int location = glGetUniformLocation(m_private->program, "uniLightDir");
-    CHECK_GL(glUniform3fv(location, 1, glm::value_ptr(lightDir)));
-    m_private->drawableObj.draw();
+    for (auto model : models) {
+        glm::mat4x4 viewModel = view * model; // ModelView
+
+        // 加载投影矩阵
+        glMatrixMode(GL_PROJECTION);
+        glLoadMatrixf(glm::value_ptr(projection));
+
+        // 加载模型视图矩阵
+        glMatrixMode(GL_MODELVIEW);
+        glLoadMatrixf(glm::value_ptr(viewModel));
+
+        glColor3f(i & 1, (i & 2) >> 1, (i & 4) >> 2); // RGB, 对应 opencv 颜色
+        glBegin(GL_TRIANGLES);
+        for (auto const& v : faces) {
+            auto a = vertices[v.x].position,
+                 b = vertices[v.y].position,
+                 c = vertices[v.z].position;
+
+            glNormal3fv(glm::value_ptr(normals[v[0]]));
+            glVertex3fv(glm::value_ptr(a));
+            glNormal3fv(glm::value_ptr(normals[v[1]]));
+            glVertex3fv(glm::value_ptr(b));
+            glNormal3fv(glm::value_ptr(normals[v[2]]));
+            glVertex3fv(glm::value_ptr(c));
+        }
+        CHECK_GL(glEnd());
+        i <<= 1;
+    }
 }