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
|
/**
* Test GLSL gl_FragCoord fragment program attribute.
* Color the quad's fragments according to their window position.
*
* Brian Paul
* 20 Nov 2008
*/
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glew.h>
#include <GL/glut.h>
#include "shaderutil.h"
static GLint WinWidth = 200, WinHeight = 200;
static char *FragProgFile = NULL;
static char *VertProgFile = NULL;
static GLuint fragShader;
static GLuint vertShader;
static GLuint program;
static GLint win = 0;
static GLboolean Anim = GL_TRUE;
static GLfloat PosX = 0.0, PosY = 0.0;
static void
Idle(void)
{
float r = (WinWidth < WinHeight) ? WinWidth : WinHeight;
float a = glutGet(GLUT_ELAPSED_TIME) * 0.001;
r *= 0.25;
PosX = WinWidth / 2 + r * cos(a);
PosY = WinHeight / 2 + r * sin(a);
glutPostRedisplay();
}
static void
Redisplay(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glTranslatef(PosX, PosY, 0.0);
#if 0
glBegin(GL_POLYGON);
glVertex2f(-50, -50);
glVertex2f( 50, -50);
glVertex2f( 50, 50);
glVertex2f(-50, 50);
glEnd();
#else
glutSolidSphere(50, 20, 10);
#endif
glPopMatrix();
glutSwapBuffers();
}
static void
Reshape(int width, int height)
{
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, width, 0, height, -55, 55);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
WinWidth = width;
WinHeight = height;
}
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 ' ':
case 'a':
Anim = !Anim;
glutIdleFunc(Anim ? Idle : NULL);
break;
case 27:
CleanUp();
exit(0);
break;
}
glutPostRedisplay();
}
static void
Init(void)
{
static const char *fragShaderText =
"void main() { \n"
" vec4 scale = vec4(.005, 0.005, 0.5, 1.0);\n"
" gl_FragColor = gl_FragCoord * scale; \n"
"}\n";
static const char *vertShaderText =
"void main() {\n"
" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
"}\n";
if (!ShadersSupported())
exit(1);
vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
program = LinkShaders(vertShader, fragShader);
glUseProgram(program);
/*assert(glGetError() == 0);*/
glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
assert(glIsProgram(program));
assert(glIsShader(fragShader));
assert(glIsShader(vertShader));
glColor3f(1, 0, 0);
}
static void
ParseOptions(int argc, char *argv[])
{
int i;
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-fs") == 0) {
FragProgFile = argv[i+1];
}
else if (strcmp(argv[i], "-vs") == 0) {
VertProgFile = argv[i+1];
}
}
}
int
main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowSize(WinWidth, WinHeight);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
win = glutCreateWindow(argv[0]);
glewInit();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Redisplay);
ParseOptions(argc, argv);
Init();
glutIdleFunc(Anim ? Idle : NULL);
glutMainLoop();
return 0;
}
|
