src/trivial/quad-tex-alpha.c

   1 /*
   2  * Copyright (c) 1991, 1992, 1993 Silicon Graphics, Inc.
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and
   5  * its documentation for any purpose is hereby granted without fee, provided
   6  * that (i) the above copyright notices and this permission notice appear in
   7  * all copies of the software and related documentation, and (ii) the name of
   8  * Silicon Graphics may not be used in any advertising or
   9  * publicity relating to the software without the specific, prior written
  10  * permission of Silicon Graphics.
  11  *
  12  * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF
  13  * ANY KIND,
  14  * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
  15  * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
  16  *
  17  * IN NO EVENT SHALL SILICON GRAPHICS BE LIABLE FOR
  18  * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  19  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  20  * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
  21  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  22  * OF THIS SOFTWARE.
  23  */
  24
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <stdlib.h>
  28 #include "gl_wrap.h"
  29 #include "glut_wrap.h"
  30
  31
  32 #define CI_OFFSET_1 16
  33 #define CI_OFFSET_2 32
  34
  35
  36 GLenum doubleBuffer;
  37
  38 static void Init(void)
  39 {
  40    fprintf(stderr, "GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
  41    fprintf(stderr, "GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
  42    fprintf(stderr, "GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
  43    fflush(stderr);
  44
  45     glClearColor(0.0, 0.0, 1.0, 0.0);
  46
  47 #define SIZE 16
  48    {
  49       GLubyte tex2d[SIZE][SIZE][4];
  50       GLint s, t;
  51
  52       for (s = 0; s < SIZE; s++) {
  53          for (t = 0; t < SIZE; t++) {
  54             tex2d[t][s][0] = (s < SIZE/2) ? 0 : 255;
  55             tex2d[t][s][1] = (t < SIZE/2) ? 0 : 255;
  56             tex2d[t][s][2] = 0;
  57             tex2d[t][s][3] = ((t^s) & 3) * 63;
  58          }
  59       }
  60
  61       glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
  62       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_REPEAT);
  63       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  64       glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
  65
  66       glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  67       glTexImage2D(GL_TEXTURE_2D, 0, 4, SIZE, SIZE, 0,
  68                    GL_RGBA, GL_UNSIGNED_BYTE, tex2d);
  69       glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
  70       glEnable(GL_TEXTURE_2D);
  71    }
  72 }
  73
  74 static void Reshape(int width, int height)
  75 {
  76
  77     glViewport(0, 0, (GLint)width, (GLint)height);
  78
  79     glMatrixMode(GL_PROJECTION);
  80     glLoadIdentity();
  81     glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
  82     glMatrixMode(GL_MODELVIEW);
  83 }
  84
  85 static void Key(unsigned char key, int x, int y)
  86 {
  87
  88     switch (key) {
  89       case 27:
  90         exit(1);
  91       default:
  92         break;
  93     }
  94
  95     glutPostRedisplay();
  96 }
  97
  98 static void Draw(void)
  99 {
 100    glClear(GL_COLOR_BUFFER_BIT);
 101
 102    glDisable(GL_DEPTH_TEST);
 103    glDisable(GL_STENCIL_TEST);
 104    glEnable(GL_ALPHA_TEST);
 105    glAlphaFunc(GL_GEQUAL, 0.5);
 106
 107    glBegin(GL_QUADS);
 108    glTexCoord2f(1,0);
 109    glVertex3f( 0.9, -0.9, -30.0);
 110    glTexCoord2f(1,1);
 111    glVertex3f( 0.9,  0.9, -30.0);
 112    glTexCoord2f(0,1);
 113    glVertex3f(-0.9,  0.9, -30.0);
 114    glTexCoord2f(0,0);
 115    glVertex3f(-0.9,  -0.9, -30.0);
 116    glEnd();
 117
 118
 119    glFlush();
 120
 121    if (doubleBuffer) {
 122       glutSwapBuffers();
 123    }
 124 }
 125
 126 static GLenum Args(int argc, char **argv)
 127 {
 128     GLint i;
 129
 130     doubleBuffer = GL_FALSE;
 131
 132     for (i = 1; i < argc; i++) {
 133         if (strcmp(argv[i], "-sb") == 0) {
 134             doubleBuffer = GL_FALSE;
 135         } else if (strcmp(argv[i], "-db") == 0) {
 136             doubleBuffer = GL_TRUE;
 137         } else {
 138             fprintf(stderr, "%s (Bad option).\n", argv[i]);
 139             return GL_FALSE;
 140         }
 141     }
 142     return GL_TRUE;
 143 }
 144
 145 int main(int argc, char **argv)
 146 {
 147     GLenum type;
 148
 149     glutInit(&argc, argv);
 150
 151     if (Args(argc, argv) == GL_FALSE) {
 152         exit(1);
 153     }
 154
 155     glutInitWindowPosition(100, 0); glutInitWindowSize( 250, 250);
 156
 157     type = GLUT_RGB;
 158     type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
 159     glutInitDisplayMode(type);
 160
 161     if (glutCreateWindow(*argv) == GL_FALSE) {
 162         exit(1);
 163     }
 164
 165     Init();
 166
 167     glutReshapeFunc(Reshape);
 168     glutKeyboardFunc(Key);
 169     glutDisplayFunc(Draw);
 170     glutMainLoop();
 171         return 0;
 172 }