progs/demos/dissolve.c

   1 /**
   2  * Dissolve between two images using randomized/patterned stencil buffer
   3  * and varying stencil ref.
   4  *
   5  * Brian Paul
   6  * 29 Jan 2010
   7  */
   8
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <math.h>
  14 #include <GL/glut.h>
  15 #include "readtex.h"
  16
  17 #define FILE1 "../images/bw.rgb"
  18 #define FILE2 "../images/arch.rgb"
  19
  20
  21 static int Win;
  22 static int WinWidth = 400, WinHeight = 400;
  23 static GLboolean Anim = GL_TRUE;
  24
  25 static int ImgWidth[2], ImgHeight[2];
  26 static GLenum ImgFormat[2];
  27 static GLubyte *Image[2];
  28 static GLfloat ScaleX[2], ScaleY[2];
  29
  30 static GLubyte StencilRef = 0;
  31
  32 static int Mode = 0;
  33
  34
  35 static void
  36 Idle(void)
  37 {
  38    StencilRef = (GLint) (glutGet(GLUT_ELAPSED_TIME) / 10);
  39    glutPostRedisplay();
  40 }
  41
  42
  43 static void
  44 FillRandomPixels(GLubyte *b)
  45 {
  46    int i;
  47    for (i = 0; i < WinWidth * WinHeight; i++) {
  48       b[i] = rand() & 0xff;
  49    }
  50 }
  51
  52
  53 static void
  54 FillRandomRects(GLubyte *b)
  55 {
  56    int i;
  57
  58    memset(b, 0, WinWidth * WinHeight);
  59
  60    for (i = 0; i < 256; i++) {
  61       int x = rand() % WinWidth;
  62       int y = rand() % WinHeight;
  63       int w = rand() % 60;
  64       int h = rand() % 60;
  65       int ix, iy;
  66
  67       if (x + w > WinWidth)
  68          w = WinWidth - x;
  69       if (y + h > WinHeight)
  70          h = WinHeight - y;
  71
  72       for (iy = 0; iy < h; iy++) {
  73          for (ix = 0; ix < w; ix++) {
  74             int p = (y + iy) * WinWidth + x + ix;
  75             b[p] = i;
  76          }
  77       }
  78    }
  79 }
  80
  81
  82 static void
  83 FillWipe(GLubyte *b)
  84 {
  85    int iy, ix;
  86
  87    memset(b, 0, WinWidth * WinHeight);
  88
  89    for (iy = 0; iy < WinHeight; iy++) {
  90       for (ix = 0; ix < WinWidth; ix++) {
  91          int p = iy * WinWidth + ix;
  92          b[p] = 2 * ix + iy / 2;
  93       }
  94    }
  95 }
  96
  97
  98 static void
  99 FillMoire(GLubyte *b)
 100 {
 101    int iy, ix;
 102
 103    memset(b, 0, WinWidth * WinHeight);
 104
 105    for (iy = 0; iy < WinHeight; iy++) {
 106       for (ix = 0; ix < WinWidth; ix++) {
 107          int p = iy * WinWidth + ix;
 108          b[p] = (ix / 2) * (ix / 2) - (iy / 2) * (iy / 2);
 109       }
 110    }
 111 }
 112
 113
 114 static void
 115 FillWaves(GLubyte *b)
 116 {
 117    int iy, ix;
 118
 119    memset(b, 0, WinWidth * WinHeight);
 120
 121    for (iy = 0; iy < WinHeight; iy++) {
 122       for (ix = 0; ix < WinWidth; ix++) {
 123          int p = iy * WinWidth + ix;
 124          float x = 8.0 * 3.1415 * ix / (float) WinWidth;
 125          b[p] = (int) (25.0 * sin(x) ) - iy*2;
 126       }
 127    }
 128 }
 129
 130
 131 typedef void (*FillFunc)(GLubyte *b);
 132
 133
 134 static FillFunc Funcs[] = {
 135    FillRandomPixels,
 136    FillRandomRects,
 137    FillWipe,
 138    FillMoire,
 139    FillWaves
 140 };
 141
 142 #define NUM_MODES (sizeof(Funcs) / sizeof(Funcs[0]))
 143
 144
 145
 146 static void
 147 InitStencilBuffer(void)
 148 {
 149    GLubyte *b = malloc(WinWidth * WinHeight);
 150
 151    Funcs[Mode](b);
 152
 153    glStencilFunc(GL_ALWAYS, 0, ~0);
 154    glPixelZoom(1.0, 1.0);
 155    glDrawPixels(WinWidth, WinHeight, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, b);
 156
 157    free(b);
 158 }
 159
 160
 161 static void
 162 Draw(void)
 163 {
 164    glClear(GL_COLOR_BUFFER_BIT);
 165
 166    glPixelZoom(ScaleX[0], ScaleY[0]);
 167    glStencilFunc(GL_LESS, StencilRef, ~0);
 168    glDrawPixels(ImgWidth[0], ImgHeight[0], ImgFormat[0], GL_UNSIGNED_BYTE, Image[0]);
 169
 170    glPixelZoom(ScaleX[1], ScaleY[1]);
 171    glStencilFunc(GL_GEQUAL, StencilRef, ~0);
 172    glDrawPixels(ImgWidth[1], ImgHeight[1], ImgFormat[1], GL_UNSIGNED_BYTE, Image[1]);
 173
 174    glutSwapBuffers();
 175 }
 176
 177
 178 static void
 179 Reshape(int width, int height)
 180 {
 181    WinWidth = width;
 182    WinHeight = height;
 183    glViewport(0, 0, width, height);
 184    glMatrixMode(GL_PROJECTION);
 185    glLoadIdentity();
 186    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
 187    glMatrixMode(GL_MODELVIEW);
 188    glLoadIdentity();
 189    glTranslatef(0.0, 0.0, -15.0);
 190
 191    InitStencilBuffer();
 192
 193    ScaleX[0] = (float) width / ImgWidth[0];
 194    ScaleY[0] = (float) height / ImgHeight[0];
 195
 196    ScaleX[1] = (float) width / ImgWidth[1];
 197    ScaleY[1] = (float) height / ImgHeight[1];
 198 }
 199
 200
 201 static void
 202 Key(unsigned char key, int x, int y)
 203 {
 204    (void) x;
 205    (void) y;
 206    switch (key) {
 207    case 'a':
 208    case ' ':
 209       Anim = !Anim;
 210       if (Anim)
 211          glutIdleFunc(Idle);
 212       else
 213          glutIdleFunc(NULL);
 214       break;
 215    case 'i':
 216       InitStencilBuffer();
 217       break;
 218    case '-':
 219       StencilRef--;
 220       break;
 221    case '+':
 222       StencilRef++;
 223       break;
 224    case 'm':
 225       Mode = (Mode + 1) % NUM_MODES;
 226       InitStencilBuffer();
 227       break;
 228    case 27:
 229       glutDestroyWindow(Win);
 230       exit(0);
 231       break;
 232    }
 233    glutPostRedisplay();
 234 }
 235
 236
 237
 238 static void
 239 Init(void)
 240 {
 241    Image[0] = LoadRGBImage(FILE1, &ImgWidth[0], &ImgHeight[0], &ImgFormat[0]);
 242    if (!Image[0]) {
 243       printf("Couldn't read %s\n", FILE1);
 244       exit(0);
 245    }
 246
 247    Image[1] = LoadRGBImage(FILE2, &ImgWidth[1], &ImgHeight[1], &ImgFormat[1]);
 248    if (!Image[1]) {
 249       printf("Couldn't read %s\n", FILE2);
 250       exit(0);
 251    }
 252
 253    glEnable(GL_STENCIL_TEST);
 254    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
 255
 256    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 257 }
 258
 259
 260 int
 261 main(int argc, char *argv[])
 262 {
 263    glutInitWindowSize(WinWidth, WinHeight);
 264    glutInit(&argc, argv);
 265    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_STENCIL);
 266    Win = glutCreateWindow(argv[0]);
 267    glutReshapeFunc(Reshape);
 268    glutKeyboardFunc(Key);
 269    glutDisplayFunc(Draw);
 270    if (Anim)
 271       glutIdleFunc(Idle);
 272    Init();
 273
 274    printf("Keys:\n");
 275    printf("  a/SPACE  toggle animation\n");
 276    printf("  +/-      single step\n");
 277    printf("  i        re-init pattern\n");
 278    printf("  m        change pattern/dissolve mode\n");
 279    printf("  ESC      exit\n");
 280
 281    glutMainLoop();
 282    return 0;
 283 }