progs/tests/rubberband.c

   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 <GL/glew.h>
   9 #include <GL/glut.h>
  10 #include "readtex.c"
  11
  12 #define IMAGE_FILE "../images/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 = 0*GL_TRUE;
  30
  31 static GLboolean RedrawBackground = GL_TRUE;
  32
  33 static const GLfloat red[4] = {1.0, 0.2, 0.2, 1.0};
  34 static const GLfloat green[4] = {0.2, 1.0, 0.2, 1.0};
  35 static const GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};
  36
  37
  38 /*
  39  * Draw rubberband box in front buffer
  40  */
  41 static void
  42 DrawRect(const struct rect *r)
  43 {
  44    glDrawBuffer(GL_FRONT);
  45
  46    if (LogicOp) {
  47       glLogicOp(GL_XOR);
  48       glEnable(GL_COLOR_LOGIC_OP);
  49    }
  50    else {
  51       glEnable(GL_BLEND);
  52       glBlendFunc(GL_ONE, GL_ONE);
  53       glBlendEquation(GL_FUNC_SUBTRACT);
  54    }
  55
  56    glColor3f(1, 1, 1);
  57
  58    glLineWidth(3.0);
  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    glDrawBuffer(GL_BACK);
  71 }
  72
  73
  74 static void
  75 PrintString(const char *s)
  76 {
  77    while (*s) {
  78       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  79       s++;
  80    }
  81 }
  82
  83
  84 static void
  85 DrawBackground(void)
  86 {
  87    char s[100];
  88
  89    sprintf(s, "[L/B] %s mode.   Use mouse to make selection box.",
  90                LogicOp ? "LogicOp" : "Blend");
  91
  92    glClear(GL_COLOR_BUFFER_BIT);
  93
  94    glWindowPos2i((Width - ImgWidth) / 2, (Height - ImgHeight) / 2);
  95    glDrawPixels(ImgWidth, ImgHeight, ImgFormat, GL_UNSIGNED_BYTE, Image);
  96
  97    glWindowPos2i(10, 10);
  98    PrintString(s);
  99
 100    glutSwapBuffers();
 101 }
 102
 103
 104 static void
 105 Draw(void)
 106 {
 107    if (RedrawBackground) {
 108       DrawBackground();
 109    }
 110
 111    if (ButtonDown) {
 112       if (!RedrawBackground)
 113          DrawRect(&OldRect); /* erase old */
 114
 115       DrawRect(&NewRect); /* draw new */
 116
 117       OldRect = NewRect;
 118    }
 119
 120    RedrawBackground = GL_FALSE;
 121 }
 122
 123
 124 static void
 125 Reshape(int width, int height)
 126 {
 127    Width = width;
 128    Height = height;
 129
 130    glViewport(0, 0, width, height);
 131
 132    glMatrixMode(GL_PROJECTION);
 133    glLoadIdentity();
 134    glOrtho(0, Width, Height, 0, -1, 1); /* Inverted Y! */
 135
 136    glMatrixMode(GL_MODELVIEW);
 137    glLoadIdentity();
 138
 139    RedrawBackground = GL_TRUE;
 140 }
 141
 142
 143 static void
 144 Key(unsigned char key, int x, int y)
 145 {
 146    (void) x;
 147    (void) y;
 148    switch (key) {
 149    case 'b':
 150    case 'B':
 151       LogicOp = GL_FALSE;
 152       break;
 153    case 'l':
 154    case 'L':
 155       LogicOp = GL_TRUE;
 156       break;
 157    case 27:
 158       glutDestroyWindow(Win);
 159       exit(0);
 160       break;
 161    }
 162    RedrawBackground = GL_TRUE;
 163    glutPostRedisplay();
 164 }
 165
 166
 167 static void
 168 SpecialKey(int key, int x, int y)
 169 {
 170    (void) x;
 171    (void) y;
 172    switch (key) {
 173    case GLUT_KEY_UP:
 174       break;
 175    case GLUT_KEY_DOWN:
 176       break;
 177    case GLUT_KEY_LEFT:
 178       break;
 179    case GLUT_KEY_RIGHT:
 180       break;
 181    }
 182    glutPostRedisplay();
 183 }
 184
 185
 186 static void
 187 MouseMotion(int x, int y)
 188 {
 189    if (ButtonDown) {
 190       NewRect.x1 = x;
 191       NewRect.y1 = y;
 192       glutPostRedisplay();
 193    }
 194 }
 195
 196
 197 static void
 198 MouseButton(int button, int state, int x, int y)
 199 {
 200   if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
 201      ButtonDown = GL_TRUE;
 202      RedrawBackground = GL_TRUE;
 203      NewRect.x0 = NewRect.x1 = x;
 204      NewRect.y0 = NewRect.y1 = y;
 205      OldRect = NewRect;
 206   }
 207   else if (button == GLUT_LEFT_BUTTON && state == GLUT_UP) {
 208      ButtonDown = GL_FALSE;
 209   }
 210   glutPostRedisplay();
 211 }
 212
 213
 214 static void
 215 Init(void)
 216 {
 217    Image = LoadRGBImage(IMAGE_FILE, &ImgWidth, &ImgHeight, &ImgFormat);
 218    if (!Image) {
 219       printf("Couldn't read %s\n", IMAGE_FILE);
 220       exit(0);
 221    }
 222
 223    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 224    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 225 }
 226
 227
 228 int
 229 main(int argc, char *argv[])
 230 {
 231    glutInit(&argc, argv);
 232    glutInitWindowSize(Width, Height);
 233    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 234    Win = glutCreateWindow(argv[0]);
 235    glewInit();
 236    glutReshapeFunc(Reshape);
 237    glutKeyboardFunc(Key);
 238    glutSpecialFunc(SpecialKey);
 239    glutMotionFunc(MouseMotion);
 240    glutMouseFunc(MouseButton);
 241    glutDisplayFunc(Draw);
 242    Init();
 243    glutPostRedisplay();
 244    glutMainLoop();
 245    return 0;
 246 }