1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
#define GL_SILENCE_DEPRECATION
#define GLFW_INCLUDE_GLCOREARB
#include <GLFW/glfw3.h>
#include <stdio.h>
#include <stdlib.h>
#include "shorthand.h"
//
// Callbacks.
//
void
glfw_error_callback(int error, const char* description) {
(void)error;
fprintf(stderr, "error: %s\n", description);
}
void
glfw_key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {
(void)mods;
(void)scancode;
if (action == GLFW_PRESS &&
(key == GLFW_KEY_ESCAPE || key == GLFW_KEY_CAPS_LOCK)) {
glfwSetWindowShouldClose(window, GLFW_TRUE);
}
}
typedef struct Context {
GLFWwindow *window;
u32 gl_version_major;
u32 gl_version_minor;
u32 win_width;
u32 win_height;
char win_title[256];
bool win_resizable;
struct {
f64 prev;
f64 elapsed;
size_t n_frames;
} frame_time;
} Context;
u32
compile_program(Context *ctx, const char *vert_src, const char *frag_src) {
// Compile vertex shader.
u32 vert_shader = glCreateShader(GL_VERTEX_SHADER);
{
glShaderSource(vert_shader, 1, &vert_src, NULL);
glCompileShader(vert_shader);
int success = 0;
glGetShaderiv(vert_shader, GL_COMPILE_STATUS, &success);
if (!success) {
fprintf(stderr, "error: vertex shader compilation failed\n");
glfwDestroyWindow(ctx->window);
glfwTerminate();
exit(EXIT_FAILURE);
}
}
// Compile fragment shader.
u32 frag_shader = glCreateShader(GL_FRAGMENT_SHADER);
{
glShaderSource(frag_shader, 1, &frag_src, NULL);
glCompileShader(frag_shader);
int success = 0;
glGetShaderiv(vert_shader, GL_COMPILE_STATUS, &success);
if (!success) {
fprintf(stderr, "error: fragment shader compilation failed\n");
glfwDestroyWindow(ctx->window);
glfwTerminate();
exit(EXIT_FAILURE);
}
}
// Link shader program.
u32 program = glCreateProgram();
{
glAttachShader(program, vert_shader);
glAttachShader(program, frag_shader);
glLinkProgram(program);
int success = 0;
glGetProgramiv(program, GL_LINK_STATUS, &success);
if(!success) {
fprintf(stderr, "error: program shader linking failed\n");
glfwDestroyWindow(ctx->window);
glfwTerminate();
exit(EXIT_FAILURE);
}
}
// Delete unused objects.
glDeleteShader(vert_shader);
glDeleteShader(frag_shader);
return program;
}
void
init_context(Context *ctx) {
if (!glfwInit()) {
fprintf(stderr, "error: GLFW initialization failed");
exit(EXIT_FAILURE);
}
// Init window and OpenGL context.
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, ctx->gl_version_major);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, ctx->gl_version_minor);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_RESIZABLE, ctx->win_resizable);
GLFWwindow* window = glfwCreateWindow(
ctx->win_width, ctx->win_height, ctx->win_title, NULL, NULL);
if (!window) {
fprintf(stderr, "error: couldn't open OpenGL window");
glfwTerminate();
exit(EXIT_FAILURE);
}
// Enable current OpenGL context and init GLAD.
glfwMakeContextCurrent(window);
// TODO: Working on macOS for now, need to check if this is needed.
// if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
// fprintf(stderr, "error: GLAD initialization failed");
// glfwDestroyWindow(window);
// glfwTerminate();
// exit(EXIT_FAILURE);
// }
ctx->window = window;
}
void
setup_callbacks(Context *ctx) {
glfwSetErrorCallback(glfw_error_callback);
glfwSetKeyCallback(ctx->window, glfw_key_callback);
}
void
update_frame_time(Context *ctx) {
// Measure frame times and fps.
f64 cur_time = glfwGetTime();
f64 delta_time = cur_time - ctx->frame_time.prev;
ctx->frame_time.elapsed += delta_time;
ctx->frame_time.n_frames++;
if (ctx->frame_time.elapsed >= 1.0) {
f64 fps = 0;
fps = ctx->frame_time.n_frames / ctx->frame_time.elapsed;
ctx->frame_time.elapsed = 0;
ctx->frame_time.n_frames = 0;
// Update title with timing data.
char title_buf[256 * 2];
sprintf(title_buf,
"%s [%.2fms, %.2f FPS]",
ctx->win_title, delta_time * 1000, fps);
glfwSetWindowTitle(ctx->window, title_buf);
}
ctx->frame_time.prev = cur_time;
}
void
update(Context *ctx) {
update_frame_time(ctx);
}
void
render(Context *ctx) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glfwSwapBuffers(ctx->window);
}
int
main(void) {
Context ctx = (Context){
.gl_version_major = 3,
.gl_version_minor = 2,
.win_width = 800,
.win_height = 600,
.win_title = "OpenGL experiments",
};
init_context(&ctx);
setup_callbacks(&ctx);
//
// Main loop.
//
ctx.frame_time.prev = glfwGetTime();
ctx.frame_time.elapsed = 0;
ctx.frame_time.n_frames = 0;
while (!glfwWindowShouldClose(ctx.window)) {
update(&ctx);
render(&ctx);
glfwPollEvents(); // constant updates.
// glfwWaitEvents(); // updates only when input arrives (better cpu usage).
}
glfwDestroyWindow(ctx.window);
glfwTerminate();
return EXIT_SUCCESS;
}
|
