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
205
206
207
208
209
|
/* Test fragment shader */
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glew.h>
#include <GL/glut.h>
static GLuint fragShader;
static GLuint vertShader;
static GLuint program;
static GLint win = 0;
static GLfloat xpos = 0, ypos = 0;
static void
Redisplay(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glTranslatef(xpos, ypos, 0);
glBegin(GL_TRIANGLES);
glColor3f(1, 0, 0);
glVertex2f(-0.9, -0.9);
glColor3f(0, 1, 0);
glVertex2f( 0.9, -0.9);
glColor3f(0, 0, 1);
glVertex2f( 0, 0.9);
glEnd();
glPopMatrix();
glutSwapBuffers();
}
static void
Reshape(int width, int height)
{
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1, 1, -1, 1, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
static void
CleanUp(void)
{
glDeleteShader(fragShader);
glDeleteShader(vertShader);
glDeleteProgram(program);
glutDestroyWindow(win);
}
static void
Key(unsigned char key, int x, int y)
{
(void) x;
(void) y;
switch(key) {
case 27:
CleanUp();
exit(0);
break;
}
glutPostRedisplay();
}
static void
SpecialKey(int key, int x, int y)
{
const GLfloat step = 0.1;
(void) x;
(void) y;
switch(key) {
case GLUT_KEY_UP:
ypos += step;
break;
case GLUT_KEY_DOWN:
ypos -= step;
break;
case GLUT_KEY_LEFT:
xpos -= step;
break;
case GLUT_KEY_RIGHT:
xpos += step;
break;
}
glutPostRedisplay();
}
static void
LoadAndCompileShader(GLuint shader, const char *text)
{
GLint stat;
glShaderSource(shader, 1, (const GLchar **) &text, NULL);
glCompileShader(shader);
glGetShaderiv(shader, GL_COMPILE_STATUS, &stat);
if (!stat) {
GLchar log[1000];
GLsizei len;
glGetShaderInfoLog(shader, 1000, &len, log);
fprintf(stderr, "fslight: problem compiling shader:\n%s\n", log);
exit(1);
}
}
static void
CheckLink(GLuint prog)
{
GLint stat;
glGetProgramiv(prog, GL_LINK_STATUS, &stat);
if (!stat) {
GLchar log[1000];
GLsizei len;
glGetProgramInfoLog(prog, 1000, &len, log);
fprintf(stderr, "Linker error:\n%s\n", log);
}
}
static void
Init(void)
{
/* fragment color is a function of fragment position: */
static const char *fragShaderText =
"void main() {\n"
" gl_FragColor = gl_FragCoord * vec4(0.005); \n"
" //gl_FragColor = gl_Color; \n"
" //gl_FragColor = vec4(1, 0, 0.5, 0); \n"
"}\n";
#if 0
static const char *vertShaderText =
"varying vec3 normal;\n"
"void main() {\n"
" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
" normal = gl_NormalMatrix * gl_Normal;\n"
"}\n";
#endif
const char *version;
version = (const char *) glGetString(GL_VERSION);
if (version[0] != '2' || version[1] != '.') {
printf("This program requires OpenGL 2.x, found %s\n", version);
exit(1);
}
fragShader = glCreateShader(GL_FRAGMENT_SHADER);
LoadAndCompileShader(fragShader, fragShaderText);
#if 0
vertShader = glCreateShader(GL_VERTEX_SHADER);
LoadAndCompileShader(vertShader, vertShaderText);
#endif
program = glCreateProgram();
glAttachShader(program, fragShader);
#if 0
glAttachShader(program, vertShader);
#endif
glLinkProgram(program);
CheckLink(program);
glUseProgram(program);
assert(glGetError() == 0);
glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
}
int
main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowPosition( 0, 0);
glutInitWindowSize(200, 200);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
win = glutCreateWindow(argv[0]);
glewInit();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutSpecialFunc(SpecialKey);
glutDisplayFunc(Redisplay);
Init();
glutMainLoop();
return 0;
}
|
