1 //========================================================================
2 // Vsync enabling test
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 //
26 // This test renders a high contrast, horizontally moving bar, allowing for
27 // visual verification of whether the set swap interval is indeed obeyed
28 //
29 //========================================================================
30
31 #include <glad/glad.h>
32 #include <GLFW/glfw3.h>
33
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <math.h>
37
38 #include "linmath.h"
39
40 static const struct
41 {
42 float x, y;
43 } vertices[4] =
44 {
45 { -0.25f, -1.f },
46 { 0.25f, -1.f },
47 { 0.25f, 1.f },
48 { -0.25f, 1.f }
49 };
50
51 static const char* vertex_shader_text =
52 "#version 110\n"
53 "uniform mat4 MVP;\n"
54 "attribute vec2 vPos;\n"
55 "void main()\n"
56 "{\n"
57 " gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
58 "}\n";
59
60 static const char* fragment_shader_text =
61 "#version 110\n"
62 "void main()\n"
63 "{\n"
64 " gl_FragColor = vec4(1.0);\n"
65 "}\n";
66
67 static int swap_tear;
68 static int swap_interval;
69 static double frame_rate;
70
update_window_title(GLFWwindow * window)71 static void update_window_title(GLFWwindow* window)
72 {
73 char title[256];
74
75 snprintf(title, sizeof(title), "Tearing detector (interval %i%s, %0.1f Hz)",
76 swap_interval,
77 (swap_tear && swap_interval < 0) ? " (swap tear)" : "",
78 frame_rate);
79
80 glfwSetWindowTitle(window, title);
81 }
82
set_swap_interval(GLFWwindow * window,int interval)83 static void set_swap_interval(GLFWwindow* window, int interval)
84 {
85 swap_interval = interval;
86 glfwSwapInterval(swap_interval);
87 update_window_title(window);
88 }
89
error_callback(int error,const char * description)90 static void error_callback(int error, const char* description)
91 {
92 fprintf(stderr, "Error: %s\n", description);
93 }
94
key_callback(GLFWwindow * window,int key,int scancode,int action,int mods)95 static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
96 {
97 if (action != GLFW_PRESS)
98 return;
99
100 switch (key)
101 {
102 case GLFW_KEY_UP:
103 {
104 if (swap_interval + 1 > swap_interval)
105 set_swap_interval(window, swap_interval + 1);
106 break;
107 }
108
109 case GLFW_KEY_DOWN:
110 {
111 if (swap_tear)
112 {
113 if (swap_interval - 1 < swap_interval)
114 set_swap_interval(window, swap_interval - 1);
115 }
116 else
117 {
118 if (swap_interval - 1 >= 0)
119 set_swap_interval(window, swap_interval - 1);
120 }
121 break;
122 }
123
124 case GLFW_KEY_ESCAPE:
125 glfwSetWindowShouldClose(window, 1);
126 break;
127
128 case GLFW_KEY_F11:
129 case GLFW_KEY_ENTER:
130 {
131 static int x, y, width, height;
132
133 if (mods != GLFW_MOD_ALT)
134 return;
135
136 if (glfwGetWindowMonitor(window))
137 glfwSetWindowMonitor(window, NULL, x, y, width, height, 0);
138 else
139 {
140 GLFWmonitor* monitor = glfwGetPrimaryMonitor();
141 const GLFWvidmode* mode = glfwGetVideoMode(monitor);
142 glfwGetWindowPos(window, &x, &y);
143 glfwGetWindowSize(window, &width, &height);
144 glfwSetWindowMonitor(window, monitor,
145 0, 0, mode->width, mode->height,
146 mode->refreshRate);
147 }
148
149 break;
150 }
151 }
152 }
153
main(int argc,char ** argv)154 int main(int argc, char** argv)
155 {
156 unsigned long frame_count = 0;
157 double last_time, current_time;
158 GLFWwindow* window;
159 GLuint vertex_buffer, vertex_shader, fragment_shader, program;
160 GLint mvp_location, vpos_location;
161
162 glfwSetErrorCallback(error_callback);
163
164 if (!glfwInit())
165 exit(EXIT_FAILURE);
166
167 glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
168 glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
169
170 window = glfwCreateWindow(640, 480, "Tearing detector", NULL, NULL);
171 if (!window)
172 {
173 glfwTerminate();
174 exit(EXIT_FAILURE);
175 }
176
177 glfwMakeContextCurrent(window);
178 gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);
179 set_swap_interval(window, 0);
180
181 last_time = glfwGetTime();
182 frame_rate = 0.0;
183 swap_tear = (glfwExtensionSupported("WGL_EXT_swap_control_tear") ||
184 glfwExtensionSupported("GLX_EXT_swap_control_tear"));
185
186 glfwSetKeyCallback(window, key_callback);
187
188 glGenBuffers(1, &vertex_buffer);
189 glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
190 glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
191
192 vertex_shader = glCreateShader(GL_VERTEX_SHADER);
193 glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
194 glCompileShader(vertex_shader);
195
196 fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
197 glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
198 glCompileShader(fragment_shader);
199
200 program = glCreateProgram();
201 glAttachShader(program, vertex_shader);
202 glAttachShader(program, fragment_shader);
203 glLinkProgram(program);
204
205 mvp_location = glGetUniformLocation(program, "MVP");
206 vpos_location = glGetAttribLocation(program, "vPos");
207
208 glEnableVertexAttribArray(vpos_location);
209 glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
210 sizeof(vertices[0]), (void*) 0);
211
212 while (!glfwWindowShouldClose(window))
213 {
214 int width, height;
215 mat4x4 m, p, mvp;
216 float position = cosf((float) glfwGetTime() * 4.f) * 0.75f;
217
218 glfwGetFramebufferSize(window, &width, &height);
219
220 glViewport(0, 0, width, height);
221 glClear(GL_COLOR_BUFFER_BIT);
222
223 mat4x4_ortho(p, -1.f, 1.f, -1.f, 1.f, 0.f, 1.f);
224 mat4x4_translate(m, position, 0.f, 0.f);
225 mat4x4_mul(mvp, p, m);
226
227 glUseProgram(program);
228 glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
229 glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
230
231 glfwSwapBuffers(window);
232 glfwPollEvents();
233
234 frame_count++;
235
236 current_time = glfwGetTime();
237 if (current_time - last_time > 1.0)
238 {
239 frame_rate = frame_count / (current_time - last_time);
240 frame_count = 0;
241 last_time = current_time;
242 update_window_title(window);
243 }
244 }
245
246 glfwTerminate();
247 exit(EXIT_SUCCESS);
248 }
249
250