progs/samples/blendeq.c

   1 /*
   2 ** blendeq.c - Demonstrates the use of the blend_minmax, blend_subtract,
   3 **    and blend_logic_op extensions using glBlendEquationEXT.
   4 **
   5 **    Over a two-color backround, draw rectangles using twelve blend
   6 **    options.  The values are read back as UNSIGNED_BYTE and printed
   7 **    in hex over each value.  These values are useful for logic
   8 **    op comparisons when channels are 8 bits deep.
   9 */
  10
  11 #include <string.h>
  12 #include <stdlib.h>
  13 #include <stdio.h>
  14 #ifdef _WIN32
  15 #include <windows.h>
  16 #endif
  17 #define GL_GLEXT_PROTOTYPES
  18 #include <GL/glut.h>
  19
  20 GLenum doubleBuffer;
  21 static int dithering = 0;
  22 int use11ops = 0;
  23 int supportlogops = 0;
  24 static int doPrint = 1;
  25 static int deltaY;
  26 GLint windW, windH;
  27
  28 static const struct {
  29    GLenum mode;
  30    const char *name;
  31 } LogicOpModes[] = {
  32    { GL_SET, "GL_SET" },
  33    { GL_COPY, "GL_COPY" },
  34    { GL_NOOP, "GL_NOOP" },
  35    { GL_AND, "GL_AND" },
  36    { GL_INVERT, "GL_INVERT" },
  37    { GL_OR, "GL_OR" },
  38    { GL_XOR, "GL_XOR" },
  39    { GL_NOR, "GL_NOR" },
  40    { GL_NAND, "GL_NAND" },
  41    { GL_OR_REVERSE, "GL_OR_REVERSE" },
  42    { GL_OR_INVERTED, "GL_OR_INVERTED" },
  43    { GL_AND_INVERTED, "GL_AND_INVERTED" },
  44    { 0, NULL }
  45 };
  46
  47
  48
  49 static void DrawString(const char *string)
  50 {
  51     int i;
  52
  53     for (i = 0; string[i]; i++)
  54         glutBitmapCharacter(GLUT_BITMAP_9_BY_15, string[i]);
  55 }
  56
  57 static void Init(void)
  58 {
  59
  60     glDisable(GL_DITHER);
  61     glShadeModel(GL_FLAT);
  62 }
  63
  64 static void Reshape(int width, int height)
  65 {
  66
  67     windW = (GLint)width;
  68     windH = (GLint)height;
  69
  70     glViewport(0, 0, (GLint)width, (GLint)height);
  71     deltaY = windH /20;
  72
  73     glMatrixMode(GL_PROJECTION);
  74     glLoadIdentity();
  75     gluOrtho2D(0, windW, 0, windH);
  76     glMatrixMode(GL_MODELVIEW);
  77 }
  78
  79 static void Key(unsigned char key, int x, int y)
  80 {
  81
  82     switch (key) {
  83       case 27:
  84         exit(1);
  85       case 'd':
  86         dithering = !dithering;
  87         break;
  88       case 'l':
  89         if (supportlogops == 3)
  90            use11ops = (!use11ops);
  91         if (use11ops)
  92            printf("Using GL 1.1 color logic ops.\n");
  93         else printf("Using GL_EXT_blend_logic_op.\n");
  94         break;
  95       default:
  96         return;
  97     }
  98
  99     glutPostRedisplay();
 100 }
 101
 102 static void PrintColorStrings( void )
 103 {
 104     GLubyte ubbuf[3];
 105     int i, xleft, xright;
 106     char colorString[18];
 107
 108     xleft = 5 + windW/4;
 109     xright = 5 + windW/2;
 110
 111     for (i = windH - deltaY + 4; i > 0; i-=deltaY) {
 112         glReadPixels(xleft, i+10, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, ubbuf);
 113         sprintf(colorString, "(0x%x, 0x%x, 0x%x)",
 114                 ubbuf[0], ubbuf[1], ubbuf[2]);
 115         glRasterPos2f(xleft, i);
 116         DrawString(colorString);
 117         glReadPixels(xright, i+10, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, ubbuf);
 118         sprintf(colorString, "(0x%x, 0x%x, 0x%x)",
 119                 ubbuf[0], ubbuf[1], ubbuf[2]);
 120         glRasterPos2f(xright, i);
 121         DrawString(colorString);
 122     }
 123 }
 124
 125 static void Draw(void)
 126 {
 127     int stringOffset = 5, stringx = 8;
 128     int x1, x2, xleft, xright;
 129     int i, k;
 130
 131     (dithering) ? glEnable(GL_DITHER) : glDisable(GL_DITHER);
 132     glDisable(GL_BLEND);
 133     if (supportlogops & 2)
 134        glDisable(GL_COLOR_LOGIC_OP);
 135
 136     glClearColor(0.5, 0.6, 0.1, 1.0);
 137     glClear(GL_COLOR_BUFFER_BIT);
 138
 139     /* Draw background */
 140     glColor3f(0.1, 0.1, 1.0);
 141     glRectf(0.0, 0.0, windW/2, windH);
 142
 143     /* Draw labels */
 144     glColor3f(0.8, 0.8, 0.0);
 145     i = windH - deltaY + stringOffset;
 146
 147     glRasterPos2f(stringx, i); i -= deltaY;
 148     DrawString("SOURCE");
 149     glRasterPos2f(stringx, i); i -= deltaY;
 150     DrawString("DEST");
 151     glRasterPos2f(stringx, i); i -= deltaY;
 152     DrawString("min");
 153     glRasterPos2f(stringx, i); i -= deltaY;
 154     DrawString("max");
 155     glRasterPos2f(stringx, i); i -= deltaY;
 156     DrawString("subtract");
 157     glRasterPos2f(stringx, i); i -= deltaY;
 158     DrawString("reverse_subtract");
 159     glRasterPos2f(stringx, i); i -= deltaY;
 160     DrawString("clear");
 161
 162     for (k = 0; LogicOpModes[k].name; k++) {
 163        glRasterPos2f(stringx, i);
 164        i -= deltaY;
 165        DrawString(LogicOpModes[k].name);
 166     }
 167
 168     i = windH - deltaY;
 169     x1 = windW/4;
 170     x2 = 3 * windW/4;
 171     xleft = 5 + windW/4;
 172     xright = 5 + windW/2;
 173
 174     /* Draw foreground color for comparison */
 175     glColor3f(0.9, 0.2, 0.8);
 176     glRectf(x1, i, x2, i+deltaY);
 177
 178     /* Leave one rectangle of background color */
 179
 180     /* Begin test cases */
 181     glEnable(GL_BLEND);
 182     glBlendFunc(GL_ONE, GL_ONE);
 183
 184     i -= 2*deltaY;
 185     glBlendEquationEXT(GL_MIN_EXT);
 186     glRectf(x1, i, x2, i+deltaY);
 187
 188     i -= deltaY;
 189     glBlendEquationEXT(GL_MAX_EXT);
 190     glRectf(x1, i, x2, i+deltaY);
 191
 192     i -= deltaY;
 193     glBlendEquationEXT(GL_FUNC_SUBTRACT_EXT);
 194     glRectf(x1, i, x2, i+deltaY);
 195
 196     i -= deltaY;
 197     glBlendEquationEXT(GL_FUNC_REVERSE_SUBTRACT_EXT);
 198     glRectf(x1, i, x2, i+deltaY);
 199
 200     glBlendFunc(GL_ONE, GL_ZERO);
 201     i -= deltaY;
 202     if (!use11ops)
 203        glBlendEquationEXT(GL_LOGIC_OP);
 204     else
 205        glEnable(GL_COLOR_LOGIC_OP);
 206     glLogicOp(GL_CLEAR);
 207     glRectf(x1, i, x2, i+deltaY);
 208
 209     for (k = 0; LogicOpModes[k].name; k++) {
 210        i -= deltaY;
 211        glLogicOp(LogicOpModes[k].mode);
 212        glRectf(x1, i, x2, i+deltaY);
 213        if (LogicOpModes[k].mode == GL_XOR) {
 214           glRectf(x1, i+10, x2, i+5);
 215        }
 216     }
 217
 218     if (doPrint) {
 219        glDisable(GL_BLEND);
 220        if (supportlogops & 2)
 221           glDisable(GL_COLOR_LOGIC_OP);
 222        glColor3f(1.0, 1.0, 1.0);
 223        PrintColorStrings();
 224     }
 225     glFlush();
 226
 227     if (doubleBuffer) {
 228        glutSwapBuffers();
 229     }
 230
 231 }
 232
 233 static GLenum Args(int argc, char **argv)
 234 {
 235     GLint i;
 236
 237     doubleBuffer = GL_FALSE;
 238
 239     for (i = 1; i < argc; i++) {
 240         if (strcmp(argv[i], "-sb") == 0) {
 241             doubleBuffer = GL_FALSE;
 242         } else if (strcmp(argv[i], "-db") == 0) {
 243             doubleBuffer = GL_TRUE;
 244         } else {
 245             printf("%s (Bad option).\n", argv[i]);
 246             return GL_FALSE;
 247         }
 248     }
 249     return GL_TRUE;
 250 }
 251
 252 int main(int argc, char **argv)
 253 {
 254     GLenum type;
 255     char *s;
 256     char *extName1 = "GL_EXT_blend_logic_op";
 257     char *extName2 = "GL_EXT_blend_minmax";
 258     char *extName3 = "GL_EXT_blend_subtract";
 259     char *version;
 260
 261     glutInit(&argc, argv);
 262
 263     if (Args(argc, argv) == GL_FALSE) {
 264         exit(1);
 265     }
 266
 267     glutInitWindowPosition(0, 0); glutInitWindowSize( 800, 520);
 268
 269     type = GLUT_RGB;
 270     type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
 271     glutInitDisplayMode(type);
 272
 273     if (glutCreateWindow("Blend Equation") == GL_FALSE) {
 274         exit(1);
 275     }
 276
 277     /* Make sure blend_logic_op extension is there. */
 278     s = (char *) glGetString(GL_EXTENSIONS);
 279     version = (char*) glGetString(GL_VERSION);
 280     if (!s)
 281         exit(1);
 282     if (strstr(s,extName1)) {
 283         supportlogops = 1;
 284         use11ops = 0;
 285         printf("blend_logic_op extension available.\n");
 286     }
 287     if (strncmp(version,"1.1",3)>=0) {
 288         supportlogops += 2;
 289         use11ops = 1;
 290         printf("1.1 color logic ops available.\n");
 291     }
 292     if (supportlogops == 0) {
 293         printf("Blend_logic_op extension and GL 1.1 not present.\n");
 294         exit(1);
 295     }
 296     if (strstr(s,extName2) == 0) {
 297         printf("Blend_minmax extension is not present.\n");
 298         exit(1);
 299     }
 300     if (strstr(s,extName3) == 0) {
 301         printf("Blend_subtract extension is not present.\n");
 302         exit(1);
 303     }
 304
 305     Init();
 306
 307     glutReshapeFunc(Reshape);
 308     glutKeyboardFunc(Key);
 309     glutDisplayFunc(Draw);
 310     glutMainLoop();
 311     return 0;
 312 }