1 /**
2 * Test OpenGL 2.0 dx/dy functions for texcoords.
3 * Brian Paul
4 * 2 May 2007
5 *
6 * NOTE: resize the window to observe how the partial derivatives of
7 * the texcoords change.
8 */
9
10
11 #include <assert.h>
12 #include <string.h>
13 #include <stdio.h>
14 #include <stdlib.h>
15 #include <math.h>
16 #include <glad/glad.h>
17 #include "glut_wrap.h"
18 #include "shaderutil.h"
19
20
21 static char *FragProgFile = NULL;
22 static char *VertProgFile = NULL;
23 static GLuint fragShader;
24 static GLuint vertShader;
25 static GLuint program;
26 static GLuint SphereList, RectList, CurList;
27 static GLint win = 0;
28 static GLboolean anim = GL_TRUE;
29 static GLfloat xRot = 0.0f, yRot = 0.0f;
30 static GLint WinSize[2];
31 static GLint WinSizeUniform = -1;
32
33
34 static void
Redisplay(void)35 Redisplay(void)
36 {
37 glUniform2iv(WinSizeUniform, 1, WinSize);
38
39 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
40
41 glPushMatrix();
42 glRotatef(xRot, 1.0f, 0.0f, 0.0f);
43 glRotatef(yRot, 0.0f, 1.0f, 0.0f);
44 glCallList(CurList);
45 glPopMatrix();
46
47 glutSwapBuffers();
48 }
49
50
51 static void
Idle(void)52 Idle(void)
53 {
54 yRot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
55 glutPostRedisplay();
56 }
57
58
59 static void
Reshape(int width,int height)60 Reshape(int width, int height)
61 {
62 WinSize[0] = width;
63 WinSize[1] = height;
64 glViewport(0, 0, width, height);
65 glMatrixMode(GL_PROJECTION);
66 glLoadIdentity();
67 glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
68 glMatrixMode(GL_MODELVIEW);
69 glLoadIdentity();
70 glTranslatef(0.0f, 0.0f, -15.0f);
71 }
72
73
74 static void
CleanUp(void)75 CleanUp(void)
76 {
77 glDeleteShader(fragShader);
78 glDeleteShader(vertShader);
79 glDeleteProgram(program);
80 glutDestroyWindow(win);
81 }
82
83
84 static void
Key(unsigned char key,int x,int y)85 Key(unsigned char key, int x, int y)
86 {
87 (void) x;
88 (void) y;
89
90 switch(key) {
91 case ' ':
92 case 'a':
93 anim = !anim;
94 if (anim)
95 glutIdleFunc(Idle);
96 else
97 glutIdleFunc(NULL);
98 break;
99 case 'o':
100 if (CurList == SphereList)
101 CurList = RectList;
102 else
103 CurList = SphereList;
104 break;
105 case 27:
106 CleanUp();
107 exit(0);
108 break;
109 }
110 glutPostRedisplay();
111 }
112
113
114 static void
SpecialKey(int key,int x,int y)115 SpecialKey(int key, int x, int y)
116 {
117 const GLfloat step = 3.0f;
118
119 (void) x;
120 (void) y;
121
122 switch(key) {
123 case GLUT_KEY_UP:
124 xRot -= step;
125 break;
126 case GLUT_KEY_DOWN:
127 xRot += step;
128 break;
129 case GLUT_KEY_LEFT:
130 yRot -= step;
131 break;
132 case GLUT_KEY_RIGHT:
133 yRot += step;
134 break;
135 }
136 glutPostRedisplay();
137 }
138
139
140 static void
MakeSphere(void)141 MakeSphere(void)
142 {
143 GLUquadricObj *obj = gluNewQuadric();
144 SphereList = glGenLists(1);
145 gluQuadricTexture(obj, GL_TRUE);
146 glNewList(SphereList, GL_COMPILE);
147 gluSphere(obj, 2.0f, 30, 15);
148 glEndList();
149 gluDeleteQuadric(obj);
150 }
151
152
153 static void
MakeRect(void)154 MakeRect(void)
155 {
156 RectList = glGenLists(1);
157 glNewList(RectList, GL_COMPILE);
158 glBegin(GL_POLYGON);
159 glTexCoord2f(0, 0); glVertex2f(-2, -2);
160 glTexCoord2f(1, 0); glVertex2f( 2, -2);
161 glTexCoord2f(1, 1); glVertex2f( 2, 2);
162 glTexCoord2f(0, 1); glVertex2f(-2, 2);
163 glEnd();
164 glEndList();
165 }
166
167
168 static void
Init(void)169 Init(void)
170 {
171 static const char *fragShaderText =
172 "uniform ivec2 WinSize; \n"
173 "void main() {\n"
174 " vec2 d = dFdy(gl_TexCoord[0].xy) * vec2(WinSize); \n"
175 " gl_FragColor = vec4(d.x, d.y, 0.0, 1.0);\n"
176 " // gl_FragColor = gl_TexCoord[0];\n"
177 "}\n";
178 static const char *vertShaderText =
179 "void main() {\n"
180 " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
181 " gl_TexCoord[0] = gl_MultiTexCoord0;\n"
182 "}\n";
183
184 if (!ShadersSupported())
185 exit(1);
186
187 vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
188 fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
189 program = LinkShaders(vertShader, fragShader);
190
191 glUseProgram(program);
192 WinSizeUniform = glGetUniformLocation(program, "WinSize");
193
194 /*assert(glGetError() == 0);*/
195
196 glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
197 glEnable(GL_DEPTH_TEST);
198
199 MakeSphere();
200 MakeRect();
201
202 CurList = SphereList;
203
204 printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
205
206 assert(glIsProgram(program));
207 assert(glIsShader(fragShader));
208 assert(glIsShader(vertShader));
209
210 glColor3f(1, 0, 0);
211 }
212
213
214 static void
ParseOptions(int argc,char * argv[])215 ParseOptions(int argc, char *argv[])
216 {
217 int i;
218 for (i = 1; i < argc; i++) {
219 if (strcmp(argv[i], "-fs") == 0) {
220 FragProgFile = argv[i+1];
221 }
222 else if (strcmp(argv[i], "-vs") == 0) {
223 VertProgFile = argv[i+1];
224 }
225 }
226 }
227
228
229 int
main(int argc,char * argv[])230 main(int argc, char *argv[])
231 {
232 WinSize[0] = WinSize[1] = 200;
233
234 glutInit(&argc, argv);
235 glutInitWindowSize(WinSize[0], WinSize[1]);
236 glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
237 win = glutCreateWindow(argv[0]);
238 gladLoadGL();
239 glutReshapeFunc(Reshape);
240 glutKeyboardFunc(Key);
241 glutSpecialFunc(SpecialKey);
242 glutDisplayFunc(Redisplay);
243 if (anim)
244 glutIdleFunc(Idle);
245 ParseOptions(argc, argv);
246 Init();
247 glutMainLoop();
248 return 0;
249 }
250