235 lines
7.0 KiB
C
235 lines
7.0 KiB
C
//========================================================================
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// Context sharing example
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// Copyright (c) Camilla Löwy <elmindreda@glfw.org>
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//
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// This software is provided 'as-is', without any express or implied
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// warranty. In no event will the authors be held liable for any damages
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// arising from the use of this software.
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//
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// Permission is granted to anyone to use this software for any purpose,
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// including commercial applications, and to alter it and redistribute it
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// freely, subject to the following restrictions:
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//
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// 1. The origin of this software must not be misrepresented; you must not
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// claim that you wrote the original software. If you use this software
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// in a product, an acknowledgment in the product documentation would
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// be appreciated but is not required.
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//
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// 2. Altered source versions must be plainly marked as such, and must not
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// be misrepresented as being the original software.
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//
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// 3. This notice may not be removed or altered from any source
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// distribution.
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//
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//========================================================================
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#include <glad/gl.h>
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#define GLFW_INCLUDE_NONE
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#include <GLFW/glfw3.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "getopt.h"
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#include "linmath.h"
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static const char* vertex_shader_text =
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"#version 110\n"
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"uniform mat4 MVP;\n"
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"attribute vec2 vPos;\n"
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"varying vec2 texcoord;\n"
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"void main()\n"
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"{\n"
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" gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
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" texcoord = vPos;\n"
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"}\n";
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static const char* fragment_shader_text =
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"#version 110\n"
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"uniform sampler2D texture;\n"
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"uniform vec3 color;\n"
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"varying vec2 texcoord;\n"
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"void main()\n"
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"{\n"
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" gl_FragColor = vec4(color * texture2D(texture, texcoord).rgb, 1.0);\n"
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"}\n";
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static const vec2 vertices[4] =
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{
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{ 0.f, 0.f },
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{ 1.f, 0.f },
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{ 1.f, 1.f },
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{ 0.f, 1.f }
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};
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static void error_callback(int error, const char* description)
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{
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fprintf(stderr, "Error: %s\n", description);
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}
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static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
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{
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if (action == GLFW_PRESS && key == GLFW_KEY_ESCAPE)
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glfwSetWindowShouldClose(window, GLFW_TRUE);
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}
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int main(int argc, char** argv)
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{
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GLFWwindow* windows[2];
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GLuint texture, program, vertex_buffer;
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GLint mvp_location, vpos_location, color_location, texture_location;
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glfwSetErrorCallback(error_callback);
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if (!glfwInit())
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exit(EXIT_FAILURE);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
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glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
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windows[0] = glfwCreateWindow(400, 400, "First", NULL, NULL);
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if (!windows[0])
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{
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glfwTerminate();
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exit(EXIT_FAILURE);
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}
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glfwSetKeyCallback(windows[0], key_callback);
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glfwMakeContextCurrent(windows[0]);
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// Only enable vsync for the first of the windows to be swapped to
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// avoid waiting out the interval for each window
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glfwSwapInterval(1);
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// The contexts are created with the same APIs so the function
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// pointers should be re-usable between them
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gladLoadGL(glfwGetProcAddress);
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// Create the OpenGL objects inside the first context, created above
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// All objects will be shared with the second context, created below
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{
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int x, y;
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char pixels[16 * 16];
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GLuint vertex_shader, fragment_shader;
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glGenTextures(1, &texture);
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glBindTexture(GL_TEXTURE_2D, texture);
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srand((unsigned int) glfwGetTimerValue());
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for (y = 0; y < 16; y++)
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{
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for (x = 0; x < 16; x++)
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pixels[y * 16 + x] = rand() % 256;
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}
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glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 16, 16, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, pixels);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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vertex_shader = glCreateShader(GL_VERTEX_SHADER);
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glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
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glCompileShader(vertex_shader);
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fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
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glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
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glCompileShader(fragment_shader);
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program = glCreateProgram();
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glAttachShader(program, vertex_shader);
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glAttachShader(program, fragment_shader);
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glLinkProgram(program);
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mvp_location = glGetUniformLocation(program, "MVP");
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color_location = glGetUniformLocation(program, "color");
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texture_location = glGetUniformLocation(program, "texture");
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vpos_location = glGetAttribLocation(program, "vPos");
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glGenBuffers(1, &vertex_buffer);
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glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
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glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
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}
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glUseProgram(program);
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glUniform1i(texture_location, 0);
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glEnable(GL_TEXTURE_2D);
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glBindTexture(GL_TEXTURE_2D, texture);
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glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
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glEnableVertexAttribArray(vpos_location);
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glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
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sizeof(vertices[0]), (void*) 0);
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windows[1] = glfwCreateWindow(400, 400, "Second", NULL, windows[0]);
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if (!windows[1])
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{
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glfwTerminate();
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exit(EXIT_FAILURE);
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}
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// Place the second window to the right of the first
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{
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int xpos, ypos, left, right, width;
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glfwGetWindowSize(windows[0], &width, NULL);
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glfwGetWindowFrameSize(windows[0], &left, NULL, &right, NULL);
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glfwGetWindowPos(windows[0], &xpos, &ypos);
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glfwSetWindowPos(windows[1], xpos + width + left + right, ypos);
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}
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glfwSetKeyCallback(windows[1], key_callback);
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glfwMakeContextCurrent(windows[1]);
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// While objects are shared, the global context state is not and will
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// need to be set up for each context
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glUseProgram(program);
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glEnable(GL_TEXTURE_2D);
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glBindTexture(GL_TEXTURE_2D, texture);
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glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
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glEnableVertexAttribArray(vpos_location);
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glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
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sizeof(vertices[0]), (void*) 0);
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while (!glfwWindowShouldClose(windows[0]) &&
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!glfwWindowShouldClose(windows[1]))
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{
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int i;
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const vec3 colors[2] =
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{
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{ 0.8f, 0.4f, 1.f },
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{ 0.3f, 0.4f, 1.f }
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};
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for (i = 0; i < 2; i++)
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{
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int width, height;
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mat4x4 mvp;
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glfwGetFramebufferSize(windows[i], &width, &height);
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glfwMakeContextCurrent(windows[i]);
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glViewport(0, 0, width, height);
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mat4x4_ortho(mvp, 0.f, 1.f, 0.f, 1.f, 0.f, 1.f);
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glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
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glUniform3fv(color_location, 1, colors[i]);
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glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
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glfwSwapBuffers(windows[i]);
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}
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glfwWaitEvents();
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}
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glfwTerminate();
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exit(EXIT_SUCCESS);
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}
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