feat: opengl hello triangle

src/gui/viewport/OpenGLWidget.h

@@ -1,3 +1,5 @@
+#include <GL/gl.h>
+#include <GL/glext.h>
 #include <QOpenGLWidget>
 #include <iostream>
 #include <QOpenGLFunctions_3_2_Core>
@@ -7,16 +9,78 @@ class MyGLWidget : public QOpenGLWidget, protected QOpenGLFunctions_3_2_Core
 public:
     MyGLWidget(QWidget *parent) : QOpenGLWidget(parent) { }
     QSize sizeHint() const override { return QSize(-1, -1); }
+    GLuint vao;
+    GLuint shaderProgram;
 
 protected:
     void initializeGL() override
     {
         // Set up the rendering context, load shaders and other resources, etc.:
         initializeOpenGLFunctions();
-        GLuint vao;
-        glGenVertexArrays(1,&vao);
+
+        glGenVertexArrays(1, &vao);
         glBindVertexArray(vao);
 
+        float vertices[] = {
+            -0.5f, -0.5f, 0.0f,
+             0.5f, -0.5f, 0.0f,
+             0.0f,  0.5f, 0.0f
+        };
+
+        GLuint vbo;
+        // create buffer of vertices
+        glGenBuffers(1, &vbo);
+        // set purpose
+        glBindBuffer(GL_ARRAY_BUFFER, vbo);
+        // store data in the buffer
+        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+
+        // vertex shader
+        const std::string vertexShaderSource = "#version 330 core\n"
+        "layout (location = 0) in vec3 aPos;\n"
+        "void main()\n"
+        "{\n"
+        "   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
+        "}\n";
+        GLuint vertexShader;
+        // shader type
+        glCreateShader(GL_VERTEX_SHADER);
+        // convert source
+        const GLchar* vertexShaderSourceC = vertexShaderSource.c_str();
+        // create shader object
+        glShaderSource(vertexShader, 1, &vertexShaderSourceC, NULL);
+        // compile shader object
+        glCompileShader(vertexShader);
+        
+        
+        // fragment shader
+        const std::string fragmentShaderSource = "#version 330 core\n"
+        "out vec4 FragColor;\n"
+        "void main()\n"
+        "{\n"
+        "    FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
+        "}\n";
+        GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+        const GLchar* fragmentShaderSourceC = fragmentShaderSource.c_str();
+        glShaderSource(fragmentShader, 1, &fragmentShaderSourceC, NULL);
+        glCompileShader(fragmentShader);
+
+        // create shader program
+        shaderProgram = glCreateProgram();
+        // attach shaders
+        glAttachShader(shaderProgram, vertexShader);
+        glAttachShader(shaderProgram, fragmentShader);
+        // link program
+        glLinkProgram(shaderProgram);
+        
+        // delete shaders now that the program is complete
+        glDeleteShader(vertexShader);
+        glDeleteShader(fragmentShader);
+
+        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3*sizeof(GLfloat), (void*)0);
+        glEnableVertexAttribArray(0);
+
         QSurfaceFormat fmt = context()->format();
         std::cout << "format: " << (fmt.renderableType() == QSurfaceFormat::OpenGLES ? "GLES" : "Desktop") << "\n";
         std::cout << "format: " << (fmt.renderableType() == QSurfaceFormat::OpenGL ? "true" : "false") << "\n";
@@ -34,6 +98,9 @@ protected:
     {
         initializeOpenGLFunctions();
         glClear(GL_COLOR_BUFFER_BIT);
+        glUseProgram(shaderProgram);
+        glBindVertexArray(vao);
+        glDrawArrays(GL_TRIANGLES, 0, 3);
     }
 
 };