update

main.cpp

@@ -2,6 +2,7 @@
 #include "camera.h"
 #include <GLFW/glfw3.h>
 #include <algorithm>
+#include <cstddef>
 #include <functional>
 #include <glm/ext/matrix_clip_space.hpp>
 #include <glm/ext/matrix_transform.hpp>
@@ -249,7 +250,55 @@ private:
 
         const int vertex_count = cols * rows;
         std::vector<float> verts;
+        for (int i = 0; i < rows; ++i) {
+            const float v = (rows > 1) ? (float)(i) / (float)(rows - 1) : 0.0F; // normailze to 0-1
+            const float y = (v - 0.5F) * panelHeight_; // -0.5 - 0.5
+            for (int j = 0; j < cols; ++j) {
+                const float u = (cols > 1) ? (float)(j) / (float)(cols - 1) : 0.0F;
+                const float x = (u - 0.5F) * panelWidth_;
+                verts.push_back(x);
+                verts.push_back(y);
+                verts.push_back(0.0F);
+                verts.push_back(u);
+                verts.push_back(v);
+            }
+        }
         
+        std::vector<unsigned int> idx;
+        idx.reserve((cols - 1) * (rows - 1) * 6);
+        for (int r = 0; r < rows - 1; ++r) {
+            for (int c = 0; c < cols - 1; ++c) {
+                auto i0 = r * cols + c;
+                auto i1 = r * cols + c + 1;
+                auto i2 = (r + 1) * cols + c + 1;
+                auto i3 = (r + 1) * cols + c;
+                idx.push_back(i0);
+                idx.push_back(i1);
+                idx.push_back(i2);
+                idx.push_back(i0);
+                idx.push_back(i2);
+                idx.push_back(i3);
+            }
+        }
+
+        heatmapIndexCount = int(idx.size());
+        glGenVertexArrays(1, &heatmapVao_);
+        glBindVertexArray(heatmapVao_);
+
+        glGenBuffers(1, &heatmapVbo_);
+        glBindBuffer(GL_ARRAY_BUFFER, heatmapVbo_);
+        glBufferData(GL_ARRAY_BUFFER, verts.size() * sizeof(float), verts.data(), GL_STATIC_DRAW);
+
+        glGenBuffers(1, &heatmapIbo_);
+        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, heatmapIbo_);
+        glBufferData(GL_ELEMENT_ARRAY_BUFFER, idx.size() * sizeof(unsigned int), idx.data(), GL_STATIC_DRAW);
+
+        glEnableVertexAttribArray(0);
+        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(0));
+        glEnableVertexAttribArray(1);
+        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
+
+        glBindVertexArray(0);
     }
 
     bool initBgProgram() {
@@ -509,6 +558,7 @@ private:
     unsigned int heatmapVao_ = 0;
     unsigned int heatmapVbo_ = 0;
     unsigned int heatmapIbo_ = 0;
+    int heatmapIndexCount = 0;
 
     ViewPort viewport_{800, 600};
     Camera camera_{glm::vec3(0.0F, 0.0F, 2.0F)};