progs/tests/minmag.c

   1 /*
   2  * Test minification vs. magnification filtering.
   3  * Draw two quads with different filtering modes:
   4  *
   5  *    +--------------------------+  +--------------------------+
   6  *    |   MagFilter = GL_LINEAR  |  |  MagFilter = GL_LINEAR   |
   7  *    |   MinFilter = GL_LINEAR  |  |  MinFilter = GL_NEAREST  |
   8  *    +--------------------------+  +--------------------------+
   9  *
  10  * They should look different when the quad is smaller than the level 0
  11  * texture size (when minifying).
  12  */
  13
  14 #include <assert.h>
  15 #include <math.h>
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <unistd.h>
  20 #include <GL/glut.h>
  21
  22
  23 static GLint Width = 1000, Height = 500;
  24
  25
  26 static GLint TexWidth = 256, TexHeight = 256;
  27 static GLfloat Zpos = 5;
  28 static GLboolean MipMap = 0*GL_TRUE;
  29 static GLboolean LinearFilter = GL_TRUE;
  30
  31
  32 static void
  33 redraw(void)
  34 {
  35    GLfloat w = 1.0;
  36    GLfloat h = 1.0;
  37
  38    glClear( GL_COLOR_BUFFER_BIT );
  39
  40    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  41
  42    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  43
  44    glPushMatrix();
  45    glTranslatef(-1.5, 0, -Zpos);
  46       glBegin(GL_POLYGON);
  47       glTexCoord2f(0, 0);  glVertex2f(-w, -h);
  48       glTexCoord2f(1, 0);  glVertex2f( w, -h);
  49       glTexCoord2f(1, 1);  glVertex2f( w,  h);
  50       glTexCoord2f(0, 1);  glVertex2f(-w,  h);
  51       glEnd();
  52    glPopMatrix();
  53
  54    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  55
  56    glPushMatrix();
  57    glTranslatef(1.5, 0, -Zpos);
  58       glBegin(GL_POLYGON);
  59       glTexCoord2f(0, 0);  glVertex2f(-w, -h);
  60       glTexCoord2f(1, 0);  glVertex2f( w, -h);
  61       glTexCoord2f(1, 1);  glVertex2f( w,  h);
  62       glTexCoord2f(0, 1);  glVertex2f(-w,  h);
  63       glEnd();
  64    glPopMatrix();
  65
  66    glutSwapBuffers();
  67 }
  68
  69
  70 static void
  71 init(void)
  72 {
  73    GLubyte color[10][4] = {
  74       { 0, 0, 0, 0 },
  75       { 1, 0, 0, 0 },
  76       { 0, 1, 0, 0 },
  77       { 0, 0, 1, 0 },
  78       { 0, 1, 1, 0 },
  79       { 1, 0, 1, 0 },
  80       { 1, 1, 0, 0 },
  81       { 1, 0, 0, 0 },
  82       { 0, 1, 0, 0 },
  83       { 0, 0, 1, 0 }
  84    };
  85    GLubyte *texImage;
  86
  87    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
  88    printf("Left quad should be linear filtered and right should be nearest filtered.\n");
  89    printf("Press z/Z to change quad distance.\n");
  90
  91    texImage = (GLubyte*) malloc(4 * TexWidth * TexHeight * sizeof(GLubyte));
  92    assert(texImage);
  93
  94    {
  95       GLint level = 0;
  96       GLint w = TexWidth, h = TexHeight;
  97       while (1) {
  98          int i, j;
  99
 100          for (i = 0; i < h; i++) {
 101             for (j = 0;j < w; j++) {
 102                if (w==1 || h==1 || (((i / 2) ^ (j / 2)) & 1)) {
 103                   /*if (j < i) {*/
 104                   texImage[(i*w+j) * 4 + 0] = 255;
 105                   texImage[(i*w+j) * 4 + 1] = 255;
 106                   texImage[(i*w+j) * 4 + 2] = 255;
 107                   texImage[(i*w+j) * 4 + 3] = 255;
 108                }
 109                else {
 110                   texImage[(i*w+j) * 4 + 0] = color[level][0] * 255;
 111                   texImage[(i*w+j) * 4 + 1] = color[level][1] * 255;
 112                   texImage[(i*w+j) * 4 + 2] = color[level][2] * 255;
 113                   texImage[(i*w+j) * 4 + 3] = color[level][3] * 255;
 114                }
 115             }
 116          }
 117
 118          glTexImage2D(GL_TEXTURE_2D, level, GL_RGBA8, w, h, 0,
 119                       GL_RGBA, GL_UNSIGNED_BYTE, texImage);
 120
 121          printf("Texture level %d: %d x %d\n", level, w, h);
 122          if (!MipMap)
 123             break;
 124
 125          if (w == 1 && h == 1)
 126             break;
 127          if (w > 1)
 128             w /= 2;
 129          if (h > 1)
 130             h /= 2;
 131          level++;
 132       }
 133    }
 134
 135    free(texImage);
 136
 137    glClearColor(0.25, 0.25, 0.25, 1.0);
 138    glEnable(GL_TEXTURE_2D);
 139
 140    glViewport(0, 0, Width, Height);
 141 }
 142
 143
 144
 145 static void
 146 Reshape(int width, int height)
 147 {
 148    float ar = (float) width /height;
 149    Width = width;
 150    Height = height;
 151    glViewport(0, 0, width, height);
 152    glMatrixMode(GL_PROJECTION);
 153    glLoadIdentity();
 154    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 2500.0);
 155    glMatrixMode(GL_MODELVIEW);
 156    glLoadIdentity();
 157    glTranslatef(0.0, 0.0, -15.0);
 158 }
 159
 160
 161 static void
 162 Key(unsigned char key, int x, int y)
 163 {
 164    (void) x;
 165    (void) y;
 166    switch (key) {
 167    case 'z':
 168       Zpos--;
 169       break;
 170    case 'Z':
 171       Zpos++;
 172       break;
 173    case 'f':
 174       LinearFilter = !LinearFilter;
 175       break;
 176    case 27:
 177       exit(0);
 178       break;
 179    }
 180    glutPostRedisplay();
 181 }
 182
 183
 184 int
 185 main(int argc, char *argv[])
 186 {
 187    glutInit(&argc, argv);
 188    glutInitWindowPosition(0, 0);
 189    glutInitWindowSize(Width, Height);
 190    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 191    glutCreateWindow(argv[0]);
 192    glutReshapeFunc(Reshape);
 193    glutKeyboardFunc(Key);
 194    glutDisplayFunc(redraw);
 195    init();
 196    glutMainLoop();
 197    return 0;
 198 }