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/glew.h>
  21 #include <GL/glut.h>
  22
  23
  24 static GLint Width = 1000, Height = 500;
  25
  26
  27 static GLint TexWidth = 256, TexHeight = 256;
  28 static GLfloat Zpos = 5;
  29 static GLboolean MipMap = 0*GL_TRUE;
  30 static GLboolean LinearFilter = GL_TRUE;
  31
  32
  33 static void
  34 redraw(void)
  35 {
  36    GLfloat w = 1.0;
  37    GLfloat h = 1.0;
  38
  39    glClear( GL_COLOR_BUFFER_BIT );
  40
  41    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  42
  43    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  44
  45    glPushMatrix();
  46    glTranslatef(-1.5, 0, -Zpos);
  47       glBegin(GL_POLYGON);
  48       glTexCoord2f(0, 0);  glVertex2f(-w, -h);
  49       glTexCoord2f(1, 0);  glVertex2f( w, -h);
  50       glTexCoord2f(1, 1);  glVertex2f( w,  h);
  51       glTexCoord2f(0, 1);  glVertex2f(-w,  h);
  52       glEnd();
  53    glPopMatrix();
  54
  55    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
  56
  57    glPushMatrix();
  58    glTranslatef(1.5, 0, -Zpos);
  59       glBegin(GL_POLYGON);
  60       glTexCoord2f(0, 0);  glVertex2f(-w, -h);
  61       glTexCoord2f(1, 0);  glVertex2f( w, -h);
  62       glTexCoord2f(1, 1);  glVertex2f( w,  h);
  63       glTexCoord2f(0, 1);  glVertex2f(-w,  h);
  64       glEnd();
  65    glPopMatrix();
  66
  67    glutSwapBuffers();
  68 }
  69
  70
  71 static void
  72 init(void)
  73 {
  74    GLubyte color[10][4] = {
  75       { 0, 0, 0, 0 },
  76       { 1, 0, 0, 0 },
  77       { 0, 1, 0, 0 },
  78       { 0, 0, 1, 0 },
  79       { 0, 1, 1, 0 },
  80       { 1, 0, 1, 0 },
  81       { 1, 1, 0, 0 },
  82       { 1, 0, 0, 0 },
  83       { 0, 1, 0, 0 },
  84       { 0, 0, 1, 0 }
  85    };
  86    GLubyte *texImage;
  87
  88    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
  89    printf("Left quad should be linear filtered and right should be nearest filtered.\n");
  90    printf("Press z/Z to change quad distance.\n");
  91
  92    texImage = (GLubyte*) malloc(4 * TexWidth * TexHeight * sizeof(GLubyte));
  93    assert(texImage);
  94
  95    {
  96       GLint level = 0;
  97       GLint w = TexWidth, h = TexHeight;
  98       while (1) {
  99          int i, j;
 100
 101          for (i = 0; i < h; i++) {
 102             for (j = 0;j < w; j++) {
 103                if (w==1 || h==1 || (((i / 2) ^ (j / 2)) & 1)) {
 104                   /*if (j < i) {*/
 105                   texImage[(i*w+j) * 4 + 0] = 255;
 106                   texImage[(i*w+j) * 4 + 1] = 255;
 107                   texImage[(i*w+j) * 4 + 2] = 255;
 108                   texImage[(i*w+j) * 4 + 3] = 255;
 109                }
 110                else {
 111                   texImage[(i*w+j) * 4 + 0] = color[level][0] * 255;
 112                   texImage[(i*w+j) * 4 + 1] = color[level][1] * 255;
 113                   texImage[(i*w+j) * 4 + 2] = color[level][2] * 255;
 114                   texImage[(i*w+j) * 4 + 3] = color[level][3] * 255;
 115                }
 116             }
 117          }
 118
 119          glTexImage2D(GL_TEXTURE_2D, level, GL_RGBA8, w, h, 0,
 120                       GL_RGBA, GL_UNSIGNED_BYTE, texImage);
 121
 122          printf("Texture level %d: %d x %d\n", level, w, h);
 123          if (!MipMap)
 124             break;
 125
 126          if (w == 1 && h == 1)
 127             break;
 128          if (w > 1)
 129             w /= 2;
 130          if (h > 1)
 131             h /= 2;
 132          level++;
 133       }
 134    }
 135
 136    free(texImage);
 137
 138    glClearColor(0.25, 0.25, 0.25, 1.0);
 139    glEnable(GL_TEXTURE_2D);
 140
 141    glViewport(0, 0, Width, Height);
 142 }
 143
 144
 145
 146 static void
 147 Reshape(int width, int height)
 148 {
 149    float ar = (float) width /height;
 150    Width = width;
 151    Height = height;
 152    glViewport(0, 0, width, height);
 153    glMatrixMode(GL_PROJECTION);
 154    glLoadIdentity();
 155    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 2500.0);
 156    glMatrixMode(GL_MODELVIEW);
 157    glLoadIdentity();
 158    glTranslatef(0.0, 0.0, -15.0);
 159 }
 160
 161
 162 static void
 163 Key(unsigned char key, int x, int y)
 164 {
 165    (void) x;
 166    (void) y;
 167    switch (key) {
 168    case 'z':
 169       Zpos--;
 170       break;
 171    case 'Z':
 172       Zpos++;
 173       break;
 174    case 'f':
 175       LinearFilter = !LinearFilter;
 176       break;
 177    case 27:
 178       exit(0);
 179       break;
 180    }
 181    glutPostRedisplay();
 182 }
 183
 184
 185 int
 186 main(int argc, char *argv[])
 187 {
 188    glutInit(&argc, argv);
 189    glutInitWindowPosition(0, 0);
 190    glutInitWindowSize(Width, Height);
 191    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 192    glutCreateWindow(argv[0]);
 193    glewInit();
 194    glutReshapeFunc(Reshape);
 195    glutKeyboardFunc(Key);
 196    glutDisplayFunc(redraw);
 197    init();
 198    glutMainLoop();
 199    return 0;
 200 }