feat(viewport): add grid

src/gui/viewport/GLGrid.cpp

@@ -0,0 +1,64 @@
+#include "gui/viewport/GLGrid.h"
+#include <glm/ext/vector_float3.hpp>
+#include <iostream>
+
+GLGrid::GLGrid()
+{
+    initializeOpenGLFunctions();
+    init();
+}
+
+void GLGrid::init()
+{
+    glGenVertexArrays(1, &vao);
+    glBindVertexArray(vao);
+
+    initBuffers();
+
+    // unbind vertex array
+    glBindVertexArray(0);
+}
+
+void GLGrid::initBuffers()
+{
+    constexpr int gridLen = 20;
+    constexpr int gridLines = 11;
+    float halfLinesCnt = (gridLines-1)*0.5f;
+    for(int i=0; i<gridLines; ++i)
+    {
+        vertices.push_back(glm::vec3((i-halfLinesCnt)*2,0,-gridLen));
+        vertices.push_back(glm::vec3((i-halfLinesCnt)*2,0,gridLen));
+
+        vertices.push_back(glm::vec3(-gridLen,0,(i-halfLinesCnt)*2));
+        vertices.push_back(glm::vec3(gridLen,0,(i-halfLinesCnt)*2));
+
+    }
+
+    // create buffer of vertices
+    glGenBuffers(1, &vbo);
+    // set purpose
+    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+    // store data in the buffer
+    glBufferData(GL_ARRAY_BUFFER, vertices.size()*sizeof(glm::vec3), vertices.data(), GL_STATIC_DRAW);
+
+    // gives the shader a way to read 
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(GLfloat), (void*)0);
+    // disable vertex attrib array
+    glEnableVertexAttribArray(0);
+}
+
+void GLGrid::bind()
+{
+    glBindVertexArray(vao);
+}
+
+void GLGrid::unbind()
+{
+    glBindVertexArray(0);
+}
+
+void GLGrid::draw()
+{
+    bind();
+    glDrawArrays(GL_LINES, 0, vertices.size());
+}

src/gui/viewport/GLGrid.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <QOpenGLFunctions_3_2_Core>
+#include <glm/ext/vector_float3.hpp>
+
+class GLGrid
+: protected QOpenGLFunctions_3_2_Core
+{
+public:
+    GLGrid();
+    GLuint vao;
+    GLuint vbo;
+    std::vector<glm::vec3> vertices;
+
+    void init();
+    void initBuffers();
+    void bind();
+    void unbind();
+    void draw();
+};

src/gui/viewport/ViewportGLWidget.cpp

@@ -12,6 +12,7 @@ void ViewportGLWidget::initializeGL()
     initializeOpenGLFunctions();
 
     triangleMesh_ = std::make_unique<GLMesh>();
+    gridMesh_ = std::make_unique<GLGrid>();
 
     QSurfaceFormat fmt = context()->format();
     std::cout << "format: " << (fmt.renderableType() == QSurfaceFormat::OpenGLES ? "GLES" : "Desktop") << "\n";
@@ -120,6 +121,7 @@ void ViewportGLWidget::paintGL()
     curCamera.setUniform(viewMLoc);
 
 
+    gridMesh_->draw();
     triangleMesh_->draw();
 
 }

src/gui/viewport/ViewportGLWidget.h

@@ -5,6 +5,7 @@
 #include <QOpenGLFunctions_3_2_Core>
 #include "gui/viewport/GLCamera.h"
 #include "gui/viewport/GLMesh.h"
+#include "gui/viewport/GLGrid.h"
 
 class ViewportGLWidget : public QOpenGLWidget, protected QOpenGLFunctions_3_2_Core
 {
@@ -14,6 +15,7 @@ public:
     GLuint shaderProgram;
     GLCamera curCamera;
     std::unique_ptr<GLMesh> triangleMesh_ ;
+    std::unique_ptr<GLGrid> gridMesh_ ;
 
 protected:
     void initializeGL() override;