Add dynamic patch grid resolution

include/scene.h

@@ -8,12 +8,18 @@
 
 #include "fbo.h"
 
+struct Vertex {
+    glm::vec3 position;
+    glm::vec2 texCoord;
+};
+
 class Scene {
     public:
         Scene(int width, int height);
         ~Scene();
 
         void Init();
+        void GenerateGrid(int divisions, std::vector<Vertex>& verts, std::vector<GLuint>& inds);
         void Display(GLFWwindow* window);
         void DrawGui(GLFWwindow* window); 
         void Idle();

source/scene.cpp

@@ -39,6 +39,9 @@ const std::string kHGTPath = "hgt/N02E016.hgt";
 
 GLuint tex_id = -1;
 
+std::vector<Vertex> vertices;
+std::vector<GLuint> indices;
+
 } // namespace
 
 Scene::Scene(int width, int height) 
@@ -70,7 +73,7 @@ void Scene::Init() {
     // GL_DEPTH_TEST causes artifacts in meshes made up of multiple triangles
     // disabling for now
     //glEnable(GL_DEPTH_TEST);
-    //glEnable(GL_CULL_FACE);
+    glEnable(GL_CULL_FACE);
 
     fbo_.Init(window_width, window_height);
     post_fbo_.Init(window_width, window_height);
@@ -87,33 +90,70 @@ void Scene::Init() {
     Uniforms::Init();
 }
 
+void Scene::GenerateGrid(int divisions, std::vector<Vertex>& verts, std::vector<GLuint>& inds) {
+    float step = 1.0f / static_cast<float>(divisions);
+    float halfSize = 0.5f;
+
+    // Create vertices for patches
+    for (int i = 0; i <= divisions; i++) {
+        for (int j = 0; j <= divisions; j++) {
+            float x = -halfSize + j * step;
+            float y = -halfSize + i * step;
+
+            Vertex vertex;
+            vertex.position = glm::vec3(x, y, 0.0f);
+            vertex.texCoord = glm::vec2(static_cast<float>(j) / divisions, static_cast<float>(i) / divisions);
+
+            verts.push_back(vertex);
+        }
+    }
+
+    // Create indices for patches
+    for (int i = 0; i < divisions; i++) {
+        for (int j = 0; j < divisions; j++) {
+            int bottomLeft = i * (divisions + 1) + j;
+            int bottomRight = bottomLeft + 1;
+            int topLeft = bottomLeft + (divisions + 1);
+            int topRight = topLeft + 1;
+
+            inds.push_back(topLeft);
+            inds.push_back(topRight);
+            inds.push_back(bottomRight);
+            inds.push_back(bottomLeft);
+        }
+    }
+}
+
 // Currently creates a test triangle and initializes its buffers
 void Scene::InitBuffers() {
-    GLuint patch_vbo;
-
-    float patchVertices[] = {
-        // Positions        // Texture Coords
-        -0.5f, -0.5f, 0.0f,  0.0f, 0.0f,  // Bottom-left
-         0.5f, -0.5f, 0.0f,  1.0f, 0.0f,  // Bottom-right
-         0.5f,  0.5f, 0.0f,  1.0f, 1.0f,  // Top-right
-        -0.5f,  0.5f, 0.0f,  0.0f, 1.0f   // Top-left
-    };
+    int divisions = 2;  // Number of divisions along one axis of the grid
+    GenerateGrid(divisions, vertices, indices);
 
+    // Create and bind VAO, VBO, and EBO, and pass the data to OpenGL
+    GLuint vao, vbo, ebo;
     glGenVertexArrays(1, &vao_);
-    glGenBuffers(1, &patch_vbo);
+    glGenBuffers(1, &vbo);
+    glGenBuffers(1, &ebo);
+
     glBindVertexArray(vao_);
 
-    glBindBuffer(GL_ARRAY_BUFFER, patch_vbo);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(patchVertices), &patchVertices, GL_STATIC_DRAW);
+    // Bind and fill the vertex buffer
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(Vertex), vertices.data(), GL_STATIC_DRAW);
 
-    // Position attribute
+    // Bind and fill the element buffer
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
+    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLuint), indices.data(), GL_STATIC_DRAW);
+
+    // Define vertex position attribute
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, position));
     glEnableVertexAttribArray(0);
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
 
-    // Texture coordinate attribute
+    // Define texture coordinate attribute
+    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)offsetof(Vertex, texCoord));
     glEnableVertexAttribArray(1);
-    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
 
+    // Unbind VAO
     glBindVertexArray(0);
 }
 
@@ -184,7 +224,7 @@ void Scene::Display(GLFWwindow* window) {
 
     glBindVertexArray(vao_);
     glPatchParameteri(GL_PATCH_VERTICES, 4);
-    glDrawArrays(GL_PATCHES, 0, 4);
+    glDrawElements(GL_PATCHES, indices.size(), GL_UNSIGNED_INT, 0);
 
     //glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);