1 //========================================================================
2 // OpenGL triangle example
3 // Copyright (c) Camilla Löwy <elmindreda@glfw.org>
4 //
5 // This software is provided 'as-is', without any express or implied
6 // warranty. In no event will the authors be held liable for any damages
7 // arising from the use of this software.
8 //
9 // Permission is granted to anyone to use this software for any purpose,
10 // including commercial applications, and to alter it and redistribute it
11 // freely, subject to the following restrictions:
12 //
13 // 1. The origin of this software must not be misrepresented; you must not
14 // claim that you wrote the original software. If you use this software
15 // in a product, an acknowledgment in the product documentation would
16 // be appreciated but is not required.
17 //
18 // 2. Altered source versions must be plainly marked as such, and must not
19 // be misrepresented as being the original software.
20 //
21 // 3. This notice may not be removed or altered from any source
22 // distribution.
23 //
24 //========================================================================
25 //! [code]
26
27 #define GLAD_GL_IMPLEMENTATION
28 #include <glad/gl.h>
29 #define GLFW_INCLUDE_NONE
30 #include <GLFW/glfw3.h>
31
32 #include "linmath.h"
33
34 #include <stdlib.h>
35 #include <stddef.h>
36 #include <stdio.h>
37
38 typedef struct Vertex
39 {
40 vec2 pos;
41 vec3 col;
42 } Vertex;
43
44 static const Vertex vertices[3] =
45 {
46 { { -0.6f, -0.4f }, { 1.f, 0.f, 0.f } },
47 { { 0.6f, -0.4f }, { 0.f, 1.f, 0.f } },
48 { { 0.f, 0.6f }, { 0.f, 0.f, 1.f } }
49 };
50
51 static const char* vertex_shader_text =
52 "#version 330\n"
53 "uniform mat4 MVP;\n"
54 "in vec3 vCol;\n"
55 "in vec2 vPos;\n"
56 "out vec3 color;\n"
57 "void main()\n"
58 "{\n"
59 " gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
60 " color = vCol;\n"
61 "}\n";
62
63 static const char* fragment_shader_text =
64 "#version 330\n"
65 "in vec3 color;\n"
66 "out vec4 fragment;\n"
67 "void main()\n"
68 "{\n"
69 " fragment = vec4(color, 1.0);\n"
70 "}\n";
71
error_callback(int error, const char* description)72 static void error_callback(int error, const char* description)
73 {
74 fprintf(stderr, "Error: %s\n", description);
75 }
76
key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)77 static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
78 {
79 if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
80 glfwSetWindowShouldClose(window, GLFW_TRUE);
81 }
82
main(void)83 int main(void)
84 {
85 glfwSetErrorCallback(error_callback);
86
87 if (!glfwInit())
88 exit(EXIT_FAILURE);
89
90 glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
91 glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
92 glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
93
94 GLFWwindow* window = glfwCreateWindow(640, 480, "OpenGL Triangle", NULL, NULL);
95 if (!window)
96 {
97 glfwTerminate();
98 exit(EXIT_FAILURE);
99 }
100
101 glfwSetKeyCallback(window, key_callback);
102
103 glfwMakeContextCurrent(window);
104 gladLoadGL(glfwGetProcAddress);
105 glfwSwapInterval(1);
106
107 // NOTE: OpenGL error checks have been omitted for brevity
108
109 GLuint vertex_buffer;
110 glGenBuffers(1, &vertex_buffer);
111 glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
112 glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
113
114 const GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
115 glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
116 glCompileShader(vertex_shader);
117
118 const GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
119 glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
120 glCompileShader(fragment_shader);
121
122 const GLuint program = glCreateProgram();
123 glAttachShader(program, vertex_shader);
124 glAttachShader(program, fragment_shader);
125 glLinkProgram(program);
126
127 const GLint mvp_location = glGetUniformLocation(program, "MVP");
128 const GLint vpos_location = glGetAttribLocation(program, "vPos");
129 const GLint vcol_location = glGetAttribLocation(program, "vCol");
130
131 GLuint vertex_array;
132 glGenVertexArrays(1, &vertex_array);
133 glBindVertexArray(vertex_array);
134 glEnableVertexAttribArray(vpos_location);
135 glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
136 sizeof(Vertex), (void*) offsetof(Vertex, pos));
137 glEnableVertexAttribArray(vcol_location);
138 glVertexAttribPointer(vcol_location, 3, GL_FLOAT, GL_FALSE,
139 sizeof(Vertex), (void*) offsetof(Vertex, col));
140
141 while (!glfwWindowShouldClose(window))
142 {
143 int width, height;
144 glfwGetFramebufferSize(window, &width, &height);
145 const float ratio = width / (float) height;
146
147 glViewport(0, 0, width, height);
148 glClear(GL_COLOR_BUFFER_BIT);
149
150 mat4x4 m, p, mvp;
151 mat4x4_identity(m);
152 mat4x4_rotate_Z(m, m, (float) glfwGetTime());
153 mat4x4_ortho(p, -ratio, ratio, -1.f, 1.f, 1.f, -1.f);
154 mat4x4_mul(mvp, p, m);
155
156 glUseProgram(program);
157 glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) &mvp);
158 glBindVertexArray(vertex_array);
159 glDrawArrays(GL_TRIANGLES, 0, 3);
160
161 glfwSwapBuffers(window);
162 glfwPollEvents();
163 }
164
165 glfwDestroyWindow(window);
166
167 glfwTerminate();
168 exit(EXIT_SUCCESS);
169 }
170
171 //! [code]
172