1 /**
2 * Test rubber-band selection box w/ logicops and blend.
3 */
4
5 #include <stdio.h>
6 #include <stdlib.h>
7 #include <math.h>
8 #include <glad/glad.h>
9 #include "glut_wrap.h"
10 #include "readtex.c"
11
12 #define IMAGE_FILE DEMOS_DATA_DIR "arch.rgb"
13
14 static int ImgWidth, ImgHeight;
15 static GLenum ImgFormat;
16 static GLubyte *Image = NULL;
17
18 static int Win;
19 static int Width = 512, Height = 512;
20
21 struct rect
22 {
23 int x0, y0, x1, y1;
24 };
25
26 static struct rect OldRect, NewRect;
27
28 static GLboolean ButtonDown = GL_FALSE;
29 static GLboolean LogicOp = GL_TRUE;
30
31 static GLboolean RedrawBackground = GL_TRUE;
32
33 static int color = 0;
34
35
36 /*
37 * Draw rubberband box in front buffer
38 */
39 static void
DrawRect(const struct rect * r)40 DrawRect(const struct rect *r)
41 {
42 glDrawBuffer(GL_FRONT);
43
44 if (LogicOp) {
45 glLogicOp(GL_XOR);
46 glEnable(GL_COLOR_LOGIC_OP);
47
48 if (color == 0)
49 glColor3f(1, 1, 1);
50 else
51 glColor3ub(152, 105, 58);
52 }
53 else {
54 glEnable(GL_BLEND);
55 glBlendFunc(GL_ONE, GL_ONE);
56 glBlendEquation(GL_FUNC_SUBTRACT);
57 glColor3f(1, 1, 1);
58 }
59
60 glBegin(GL_LINE_LOOP);
61 glVertex2i(r->x0, r->y0);
62 glVertex2i(r->x1, r->y0);
63 glVertex2i(r->x1, r->y1);
64 glVertex2i(r->x0, r->y1);
65 glEnd();
66
67 glDisable(GL_COLOR_LOGIC_OP);
68 glDisable(GL_BLEND);
69
70 /* Need this to ensure the front buffer drawing is actually displayed */
71 glFlush();
72
73 glDrawBuffer(GL_BACK);
74 }
75
76
77 static void
PrintString(const char * s)78 PrintString(const char *s)
79 {
80 while (*s) {
81 glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
82 s++;
83 }
84 }
85
86
87 static void
DrawBackground(void)88 DrawBackground(void)
89 {
90 char s[100];
91
92 sprintf(s, "[L/B] %s mode. Use mouse to make selection box.",
93 LogicOp ? "LogicOp" : "Blend");
94
95 glClear(GL_COLOR_BUFFER_BIT);
96
97 glWindowPos2i((Width - ImgWidth) / 2, (Height - ImgHeight) / 2);
98 glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
99
100 glColor3f(1, 1, 1);
101 glWindowPos2i(10, 10);
102 PrintString(s);
103
104 glutSwapBuffers();
105 }
106
107
108 static void
Draw(void)109 Draw(void)
110 {
111 if (RedrawBackground) {
112 DrawBackground();
113 }
114
115 if (ButtonDown) {
116 if (!RedrawBackground)
117 DrawRect(&OldRect); /* erase old */
118
119 DrawRect(&NewRect); /* draw new */
120
121 OldRect = NewRect;
122 }
123
124 RedrawBackground = GL_FALSE;
125 }
126
127
128 static void
Reshape(int width,int height)129 Reshape(int width, int height)
130 {
131 Width = width;
132 Height = height;
133
134 glViewport(0, 0, width, height);
135
136 glMatrixMode(GL_PROJECTION);
137 glLoadIdentity();
138 glOrtho(0, Width, Height, 0, -1, 1); /* Inverted Y! */
139
140 glMatrixMode(GL_MODELVIEW);
141 glLoadIdentity();
142
143 RedrawBackground = GL_TRUE;
144 }
145
146
147 static void
Key(unsigned char key,int x,int y)148 Key(unsigned char key, int x, int y)
149 {
150 (void) x;
151 (void) y;
152 switch (key) {
153 case '1':
154 glLineWidth(1);
155 break;
156 case '2':
157 glLineWidth(2);
158 break;
159 case '3':
160 glLineWidth(3);
161 break;
162 case '4':
163 glLineWidth(4);
164 break;
165 case 'b':
166 case 'B':
167 LogicOp = GL_FALSE;
168 break;
169 case 'c':
170 case 'C':
171 color = !color;
172 printf("using color %d\n", color);
173 fflush(stdout);
174 break;
175 case 'l':
176 case 'L':
177 LogicOp = GL_TRUE;
178 break;
179 case 27:
180 glutDestroyWindow(Win);
181 exit(0);
182 break;
183 }
184 RedrawBackground = GL_TRUE;
185 glutPostRedisplay();
186 }
187
188
189 static void
SpecialKey(int key,int x,int y)190 SpecialKey(int key, int x, int y)
191 {
192 (void) x;
193 (void) y;
194 switch (key) {
195 case GLUT_KEY_UP:
196 break;
197 case GLUT_KEY_DOWN:
198 break;
199 case GLUT_KEY_LEFT:
200 break;
201 case GLUT_KEY_RIGHT:
202 break;
203 }
204 glutPostRedisplay();
205 }
206
207
208 static void
MouseMotion(int x,int y)209 MouseMotion(int x, int y)
210 {
211 if (ButtonDown) {
212 NewRect.x1 = x;
213 NewRect.y1 = y;
214 glutPostRedisplay();
215 }
216 }
217
218
219 static void
MouseButton(int button,int state,int x,int y)220 MouseButton(int button, int state, int x, int y)
221 {
222 if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
223 ButtonDown = GL_TRUE;
224 RedrawBackground = GL_TRUE;
225 NewRect.x0 = NewRect.x1 = x;
226 NewRect.y0 = NewRect.y1 = y;
227 OldRect = NewRect;
228 }
229 else if (button == GLUT_LEFT_BUTTON && state == GLUT_UP) {
230 ButtonDown = GL_FALSE;
231 }
232 glutPostRedisplay();
233 }
234
235
236 static void
Init(void)237 Init(void)
238 {
239 Image = LoadRGBImage(IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat);
240 if (!Image) {
241 printf("Couldn't read %s\n", IMAGE_FILE);
242 exit(0);
243 }
244
245 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
246 glPixelStorei(GL_PACK_ALIGNMENT, 1);
247 glLineWidth(3);
248 }
249
250
251 int
main(int argc,char * argv[])252 main(int argc, char *argv[])
253 {
254 glutInit(&argc, argv);
255 glutInitWindowSize(Width, Height);
256 glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
257 Win = glutCreateWindow(argv[0]);
258 gladLoadGL();
259 glutReshapeFunc(Reshape);
260 glutKeyboardFunc(Key);
261 glutSpecialFunc(SpecialKey);
262 glutMotionFunc(MouseMotion);
263 glutMouseFunc(MouseButton);
264 glutDisplayFunc(Draw);
265 Init();
266 glutPostRedisplay();
267 glutMainLoop();
268 return 0;
269 }
270