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1//========================================================================
2// Empty event test
3// Copyright (c) Camilla Löwy <[email protected]>
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 is intended to verify that the posting of empty events works.
27// Background colors are produced on a secondary thread, which then wakes
28// the main thread with glfwPostEmptyEvent when a new one is available.
29// This allows the main thread to wait for events unconditionally.
30//
31//========================================================================
32
33#include "tinycthread.h"
34
35#define GLAD_GL_IMPLEMENTATION
36#include <glad/gl.h>
37#define GLFW_INCLUDE_NONE
38#include <GLFW/glfw3.h>
39
40#include <math.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <stdbool.h>
44
45struct State
46{
47    mtx_t lock;
48    bool running;
49    bool needs_update;
50    int width;
51    int height;
52    float r, g, b;
53};
54
55static void error_callback(int error, const char* description)
56{
57    fprintf(stderr, "Error: %s\n", description);
58}
59
60static void generate_color(struct State* state)
61{
62    const float r = (float) rand() / (float) RAND_MAX;
63    const float g = (float) rand() / (float) RAND_MAX;
64    const float b = (float) rand() / (float) RAND_MAX;
65    const float l = sqrtf(r * r + g * g + b * b);
66
67    mtx_lock(&state->lock);
68    state->r = r / l;
69    state->g = g / l;
70    state->b = b / l;
71    state->needs_update = true;
72    mtx_unlock(&state->lock);
73}
74
75static int thread_main(void* data)
76{
77    struct State* const state = data;
78
79    srand((unsigned int) time(NULL));
80
81    while (state->running)
82    {
83        generate_color(state);
84        glfwPostEmptyEvent();
85
86        struct timespec time;
87        clock_gettime(CLOCK_REALTIME, &time);
88        time.tv_sec += 1;
89        thrd_sleep(&time, NULL);
90    }
91
92    return 0;
93}
94
95static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
96{
97    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
98        glfwSetWindowShouldClose(window, true);
99}
100
101static void framebuffer_size_callback(GLFWwindow* window, int width, int height)
102{
103    struct State* const state = glfwGetWindowUserPointer(window);
104
105    mtx_lock(&state->lock);
106    state->width = width;
107    state->height = height;
108    state->needs_update = true;
109    mtx_unlock(&state->lock);
110}
111
112int main(void)
113{
114    struct State state = { .running = true };
115
116    if (mtx_init(&state.lock, mtx_plain) != thrd_success)
117    {
118        glfwTerminate();
119        exit(EXIT_FAILURE);
120    }
121
122    generate_color(&state);
123
124    glfwSetErrorCallback(error_callback);
125
126    if (!glfwInit())
127        exit(EXIT_FAILURE);
128
129    GLFWwindow* window = glfwCreateWindow(640, 480, "Empty Event Test", NULL, NULL);
130    if (!window)
131    {
132        glfwTerminate();
133        exit(EXIT_FAILURE);
134    }
135
136    glfwMakeContextCurrent(window);
137    gladLoadGL(glfwGetProcAddress);
138    glfwSetKeyCallback(window, key_callback);
139    glfwSetWindowUserPointer(window, &state);
140    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
141    glfwGetFramebufferSize(window, &state.width, &state.height);
142
143    thrd_t color_thread;
144
145    if (thrd_create(&color_thread, thread_main, &state) != thrd_success)
146    {
147        fprintf(stderr, "Failed to create secondary thread\n");
148
149        glfwTerminate();
150        exit(EXIT_FAILURE);
151    }
152
153    while (!glfwWindowShouldClose(window))
154    {
155        if (state.needs_update)
156        {
157            mtx_lock(&state.lock);
158            glViewport(0, 0, state.width, state.height);
159            glClearColor(state.r, state.g, state.b, 1.f);
160            state.needs_update = false;
161            mtx_unlock(&state.lock);
162
163            glClear(GL_COLOR_BUFFER_BIT);
164            glfwSwapBuffers(window);
165        }
166
167        glfwWaitEvents();
168    }
169
170    glfwHideWindow(window);
171    state.running = false;
172    thrd_join(color_thread, NULL);
173    mtx_destroy(&state.lock);
174
175    glfwTerminate();
176    exit(EXIT_SUCCESS);
177}
178
179
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