chore: extract Triangle class

CMakeLists.txt

@@ -24,7 +24,7 @@ elseif(APPLE)
     message(FATAL_ERROR "macOS is not supported yet.")
 endif()
 
-add_executable(${PROJECT_NAME} src/hello.cpp src/io.cpp)
+add_executable(${PROJECT_NAME} src/hello.cpp src/io.cpp src/triangle.cpp)
 
 if(WIN32)
     add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD

src/hello.cpp

@@ -45,6 +45,7 @@
 #include <chrono>
 
 #include "io.hpp"
+#include "triangle.hpp"
 
 GLuint compileShader(const std::string& shaderPath, GLenum shaderType)
 {
@@ -78,7 +79,6 @@ float getTime()
     return timeSpan.count();
 }
 
-#include <vector>
 #include <cmath>
 #include "astro/twoBodyMethods.hpp"
 
@@ -114,46 +114,8 @@ int initGraphics(GLFWwindow** window)
     return 0;
 }
 
-int main()
+GLuint getShaderProgram()
 {
-    // Calculate period of ISS orbit around the Earth
-    const float semiMajorAxis = 6738000;
-    const float gravitationalParameter = 3.986e14;
-    float period = astro::computeKeplerOrbitalPeriod(semiMajorAxis, gravitationalParameter);
-    period /= 60.0;
-    std::cout << period << std::endl;
-
-    glm::vec3 v(0.0, 1.0, 2.0);
-    std::cout << "(" << v.x << ", " << v.y << ", " << v.z << ")" << std::endl;
-
-    GLFWwindow* window = nullptr;
-    if (initGraphics(&window) != 0)
-        return -1;
-
-    // VAO, VBO
-    float vertices[] =
-    {
-        -0.5, -0.5, 0.0,    // left
-         0.5, -0.5, 0.0,    // right
-         0.0,  0.5, 0.0     // top
-    };
-
-    GLuint VBO, VAO;
-    glGenVertexArrays(1, &VAO);
-    glGenBuffers(1, &VBO);
-
-    glBindVertexArray(VAO);
-
-    glBindBuffer(GL_ARRAY_BUFFER, VBO);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
-
-    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
-    glEnableVertexAttribArray(0);
-
-    glBindBuffer(GL_ARRAY_BUFFER, 0);
-    glBindVertexArray(0);
-
-    // Shaders
     GLuint vertShader = compileShader("./vert.glsl", GL_VERTEX_SHADER);
     GLuint fragShader = compileShader("./frag.glsl", GL_FRAGMENT_SHADER);
 
@@ -176,32 +138,39 @@ int main()
     glDeleteShader(vertShader);
     glDeleteShader(fragShader);
 
+    return shaderProgram;
+}
+
+int main()
+{
+    // Calculate period of ISS orbit around the Earth
+    const float semiMajorAxis = 6738000;
+    const float gravitationalParameter = 3.986e14;
+    float period = astro::computeKeplerOrbitalPeriod(semiMajorAxis, gravitationalParameter);
+    period /= 60.0;
+    std::cout << period << std::endl;
+
+    glm::vec3 v(0.0, 1.0, 2.0);
+    std::cout << "(" << v.x << ", " << v.y << ", " << v.z << ")" << std::endl;
+
+    GLFWwindow* window = nullptr;
+    if (initGraphics(&window) != 0)
+        return -1;
+
+    Triangle triangle(getShaderProgram());
+
     // Main loop
     while (!glfwWindowShouldClose(window))
     {
         glClearColor(0.2, 0.3, 0.3, 1.0);
         glClear(GL_COLOR_BUFFER_BIT);
 
-        glUseProgram(shaderProgram);
+        triangle.render(getTime());
-
-        GLint timeLocation = glGetUniformLocation(shaderProgram, "_Time");
-        if (timeLocation == -1)
-        {
-            std::cerr << "Could not find uniform: _Time" << std::endl;
-        }
-        float timeValue = getTime();
-        glUniform1f(timeLocation, timeValue);
-
-        glBindVertexArray(VAO);
-        glDrawArrays(GL_TRIANGLES, 0, 3);
 
         glfwSwapBuffers(window);
         glfwPollEvents();
     }
 
-    glDeleteVertexArrays(1, &VAO);
-    glDeleteBuffers(1, &VBO);
-
     glfwTerminate();
     return 0;
 }

src/triangle.cpp

@@ -0,0 +1,45 @@
+#include "triangle.hpp"
+
+#include <iostream>
+
+Triangle::Triangle(GLuint shaderProgram)
+    : _shaderProgram(shaderProgram)
+{
+    glGenVertexArrays(1, &_vao);
+    glGenBuffers(1, &_vbo);
+
+    glBindVertexArray(_vao);
+
+    glBindBuffer(GL_ARRAY_BUFFER, _vbo);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(_vertices), &_vertices[0], GL_STATIC_DRAW);
+
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+    glEnableVertexAttribArray(0);
+
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+    glBindVertexArray(0);
+}
+
+void Triangle::render(float time)
+{
+	glUseProgram(_shaderProgram);
+
+	GLint timeLocation = glGetUniformLocation(_shaderProgram, "_Time");
+	if (timeLocation == -1)
+	{
+		std::cerr << "Could not find uniform: _Time" << std::endl;
+        return;
+	}
+	float timeValue = time;
+	glUniform1f(timeLocation, timeValue);
+
+    glBindBuffer(GL_ARRAY_BUFFER, _vbo);
+	glBindVertexArray(_vao);
+	glDrawArrays(GL_TRIANGLES, 0, 3);
+}
+
+Triangle::~Triangle()
+{
+    glDeleteVertexArrays(1, &_vao);
+    glDeleteBuffers(1, &_vbo);
+}

src/triangle.hpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <GL/glew.h>
+
+#include <vector>
+
+class Triangle
+{
+public:
+	Triangle(GLuint shaderProgram);
+	void render(float time);
+
+	~Triangle();
+
+private:
+	GLuint _vbo;
+	GLuint _vao;
+	GLuint _shaderProgram;
+
+	std::vector<float> _vertices =
+	{
+        -0.5, -0.5, 0.0,    // left
+         0.5, -0.5, 0.0,    // right
+         0.0,  0.5, 0.0     // top
+	};
+};