ref: 8d296f03850a2b981a90a6a62bb3663bd9effd4f
dir: /external/glfw/tests/tearing.c/
//========================================================================
// Vsync enabling test
// Copyright (c) Camilla Löwy <elmindreda@glfw.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would
// be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
// be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
// distribution.
//
//========================================================================
//
// This test renders a high contrast, horizontally moving bar, allowing for
// visual verification of whether the set swap interval is indeed obeyed
//
//========================================================================
#include <glad/gl.h>
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "linmath.h"
static const struct
{
float x, y;
} vertices[4] =
{
{ -0.25f, -1.f },
{ 0.25f, -1.f },
{ 0.25f, 1.f },
{ -0.25f, 1.f }
};
static const char* vertex_shader_text =
"#version 110\n"
"uniform mat4 MVP;\n"
"attribute vec2 vPos;\n"
"void main()\n"
"{\n"
" gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
"}\n";
static const char* fragment_shader_text =
"#version 110\n"
"void main()\n"
"{\n"
" gl_FragColor = vec4(1.0);\n"
"}\n";
static int swap_tear;
static int swap_interval;
static double frame_rate;
static void update_window_title(GLFWwindow* window)
{
char title[256];
snprintf(title, sizeof(title), "Tearing detector (interval %i%s, %0.1f Hz)",
swap_interval,
(swap_tear && swap_interval < 0) ? " (swap tear)" : "",
frame_rate);
glfwSetWindowTitle(window, title);
}
static void set_swap_interval(GLFWwindow* window, int interval)
{
swap_interval = interval;
glfwSwapInterval(swap_interval);
update_window_title(window);
}
static void error_callback(int error, const char* description)
{
fprintf(stderr, "Error: %s\n", description);
}
static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if (action != GLFW_PRESS)
return;
switch (key)
{
case GLFW_KEY_UP:
{
if (swap_interval + 1 > swap_interval)
set_swap_interval(window, swap_interval + 1);
break;
}
case GLFW_KEY_DOWN:
{
if (swap_tear)
{
if (swap_interval - 1 < swap_interval)
set_swap_interval(window, swap_interval - 1);
}
else
{
if (swap_interval - 1 >= 0)
set_swap_interval(window, swap_interval - 1);
}
break;
}
case GLFW_KEY_ESCAPE:
glfwSetWindowShouldClose(window, 1);
break;
case GLFW_KEY_F11:
case GLFW_KEY_ENTER:
{
static int x, y, width, height;
if (mods != GLFW_MOD_ALT)
return;
if (glfwGetWindowMonitor(window))
glfwSetWindowMonitor(window, NULL, x, y, width, height, 0);
else
{
GLFWmonitor* monitor = glfwGetPrimaryMonitor();
const GLFWvidmode* mode = glfwGetVideoMode(monitor);
glfwGetWindowPos(window, &x, &y);
glfwGetWindowSize(window, &width, &height);
glfwSetWindowMonitor(window, monitor,
0, 0, mode->width, mode->height,
mode->refreshRate);
}
break;
}
}
}
int main(int argc, char** argv)
{
unsigned long frame_count = 0;
double last_time, current_time;
GLFWwindow* window;
GLuint vertex_buffer, vertex_shader, fragment_shader, program;
GLint mvp_location, vpos_location;
glfwSetErrorCallback(error_callback);
if (!glfwInit())
exit(EXIT_FAILURE);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
window = glfwCreateWindow(640, 480, "Tearing detector", NULL, NULL);
if (!window)
{
glfwTerminate();
exit(EXIT_FAILURE);
}
glfwMakeContextCurrent(window);
gladLoadGL(glfwGetProcAddress);
set_swap_interval(window, 0);
last_time = glfwGetTime();
frame_rate = 0.0;
swap_tear = (glfwExtensionSupported("WGL_EXT_swap_control_tear") ||
glfwExtensionSupported("GLX_EXT_swap_control_tear"));
glfwSetKeyCallback(window, key_callback);
glGenBuffers(1, &vertex_buffer);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
vertex_shader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
glCompileShader(vertex_shader);
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
glCompileShader(fragment_shader);
program = glCreateProgram();
glAttachShader(program, vertex_shader);
glAttachShader(program, fragment_shader);
glLinkProgram(program);
mvp_location = glGetUniformLocation(program, "MVP");
vpos_location = glGetAttribLocation(program, "vPos");
glEnableVertexAttribArray(vpos_location);
glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
sizeof(vertices[0]), (void*) 0);
while (!glfwWindowShouldClose(window))
{
int width, height;
mat4x4 m, p, mvp;
float position = cosf((float) glfwGetTime() * 4.f) * 0.75f;
glfwGetFramebufferSize(window, &width, &height);
glViewport(0, 0, width, height);
glClear(GL_COLOR_BUFFER_BIT);
mat4x4_ortho(p, -1.f, 1.f, -1.f, 1.f, 0.f, 1.f);
mat4x4_translate(m, position, 0.f, 0.f);
mat4x4_mul(mvp, p, m);
glUseProgram(program);
glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
glfwSwapBuffers(window);
glfwPollEvents();
frame_count++;
current_time = glfwGetTime();
if (current_time - last_time > 1.0)
{
frame_rate = frame_count / (current_time - last_time);
frame_count = 0;
last_time = current_time;
update_window_title(window);
}
}
glfwTerminate();
exit(EXIT_SUCCESS);
}