2019/11/26
1 #include <glad/glad.h>
2 #include <GLFW/glfw3.h>
3
4 #include <iostream>
5
6 void framebuffer_size_callback(GLFWwindow* window, int width, int height);
7 void processInput(GLFWwindow *window);
8
9 // settings
10 const unsigned int SCR_WIDTH = 800;
11 const unsigned int SCR_HEIGHT = 600;
12
13 const char *vertexShaderSource = "#version 330 core\n"
14 "layout (location = 0) in vec3 aPos;\n"
15 "void main()\n"
16 "{\n"
17 " gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
18 "}\0";
19 const char *fragmentShaderSource = "#version 330 core\n"
20 "out vec4 FragColor;\n"
21 "void main()\n"
22 "{\n"
23 " FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
24 "}\n\0";
25
26 int main()
27 {
28 // glfw: initialize and configure
29 // ------------------------------
30 glfwInit();
31 glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
32 glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
33 glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
34
35 #ifdef __APPLE__
36 glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // uncomment this statement to fix compilation on OS X
37 #endif
38
39 // glfw window creation
40 // --------------------
41 GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
42 if (window == NULL)
43 {
44 std::cout << "Failed to create GLFW window" << std::endl;
45 glfwTerminate();
46 return -1;
47 }
48 glfwMakeContextCurrent(window);
49 glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
50
51 // glad: load all OpenGL function pointers
52 // ---------------------------------------
53 if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
54 {
55 std::cout << "Failed to initialize GLAD" << std::endl;
56 return -1;
57 }
58
59
60 // build and compile our shader program
61 // ------------------------------------
62 // vertex shader
63 int vertexShader = glCreateShader(GL_VERTEX_SHADER);
64 glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
65 glCompileShader(vertexShader);
66 // check for shader compile errors
67 int success;
68 char infoLog[512];
69 glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
70 if (!success)
71 {
72 glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
73 std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
74 }
75 // fragment shader
76 int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
77 glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
78 glCompileShader(fragmentShader);
79 // check for shader compile errors
80 glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
81 if (!success)
82 {
83 glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
84 std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
85 }
86 // link shaders
87 int shaderProgram = glCreateProgram();
88 glAttachShader(shaderProgram, vertexShader);
89 glAttachShader(shaderProgram, fragmentShader);
90 glLinkProgram(shaderProgram);
91 // check for linking errors
92 glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
93 if (!success) {
94 glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
95 std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
96 }
97 glDeleteShader(vertexShader);
98 glDeleteShader(fragmentShader);
99
100 // set up vertex data (and buffer(s)) and configure vertex attributes
101 // ------------------------------------------------------------------
102 // add a new set of vertices to form a second triangle (a total of 6 vertices); the vertex attribute configuration remains the same (still one 3-float position vector per vertex)
103 float vertices[] = {
104 // first triangle
105 -0.9f, -0.5f, 0.0f, // left
106 -0.0f, -0.5f, 0.0f, // right
107 -0.45f, 0.5f, 0.0f, // top
108 // second triangle
109 0.0f, -0.5f, 0.0f, // left
110 0.9f, -0.5f, 0.0f, // right
111 0.45f, 0.5f, 0.0f // top
112 };
113
114 unsigned int VBO, VAO;
115 glGenVertexArrays(1, &VAO);
116 glGenBuffers(1, &VBO);
117 // bind the Vertex Array Object first, then bind and set vertex buffer(s), and then configure vertex attributes(s).
118 glBindVertexArray(VAO);
119
120 glBindBuffer(GL_ARRAY_BUFFER, VBO);
121 glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
122
123 glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
124 glEnableVertexAttribArray(0);
125
126 // note that this is allowed, the call to glVertexAttribPointer registered VBO as the vertex attribute's bound vertex buffer object so afterwards we can safely unbind
127 glBindBuffer(GL_ARRAY_BUFFER, 0);
128
129 // You can unbind the VAO afterwards so other VAO calls won't accidentally modify this VAO, but this rarely happens. Modifying other
130 // VAOs requires a call to glBindVertexArray anyways so we generally don't unbind VAOs (nor VBOs) when it's not directly necessary.
131 glBindVertexArray(0);
132
133
134 // uncomment this call to draw in wireframe polygons.
135 //glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
136
137 // render loop
138 // -----------
139 while (!glfwWindowShouldClose(window))
140 {
141 // input
142 // -----
143 processInput(window);
144
145 // render
146 // ------
147 glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
148 glClear(GL_COLOR_BUFFER_BIT);
149
150 // draw our first triangle
151 glUseProgram(shaderProgram);
152 glBindVertexArray(VAO); // seeing as we only have a single VAO there's no need to bind it every time, but we'll do so to keep things a bit more organized
153 glDrawArrays(GL_TRIANGLES, 0, 6); // set the count to 6 since we're drawing 6 vertices now (2 triangles); not 3!
154 // glBindVertexArray(0); // no need to unbind it every time
155
156 // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
157 // -------------------------------------------------------------------------------
158 glfwSwapBuffers(window);
159 glfwPollEvents();
160 }
161
162 // optional: de-allocate all resources once they've outlived their purpose:
163 // ------------------------------------------------------------------------
164 glDeleteVertexArrays(1, &VAO);
165 glDeleteBuffers(1, &VBO);
166
167 // glfw: terminate, clearing all previously allocated GLFW resources.
168 // ------------------------------------------------------------------
169 glfwTerminate();
170 return 0;
171 }
172
173 // process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
174 // ---------------------------------------------------------------------------------------------------------
175 void processInput(GLFWwindow *window)
176 {
177 if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
178 glfwSetWindowShouldClose(window, true);
179 }
180
181 // glfw: whenever the window size changed (by OS or user resize) this callback function executes
182 // ---------------------------------------------------------------------------------------------
183 void framebuffer_size_callback(GLFWwindow* window, int width, int height)
184 {
185 // make sure the viewport matches the new window dimensions; note that width and
186 // height will be significantly larger than specified on retina displays.
187 glViewport(0, 0, width, height);
188 }