aboutsummaryrefslogtreecommitdiffstats
path: root/progs/tests/minmag.c
blob: 03019f94faa6c276747d6a52cfc167ada46ccfe2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
/*
 * Test minification vs. magnification filtering.
 * Draw two quads with different filtering modes:
 *
 *    +--------------------------+  +--------------------------+
 *    |   MagFilter = GL_LINEAR  |  |  MagFilter = GL_LINEAR   |
 *    |   MinFilter = GL_LINEAR  |  |  MinFilter = GL_NEAREST  |
 *    +--------------------------+  +--------------------------+
 *
 * They should look different when the quad is smaller than the level 0
 * texture size (when minifying).
 */

#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <GL/glew.h>
#include <GL/glut.h>


static GLint Width = 1000, Height = 500;


static GLint TexWidth = 256, TexHeight = 256;
static GLfloat Zpos = 5;
static GLboolean MipMap = 0*GL_TRUE;
static GLboolean LinearFilter = GL_TRUE;


static void
redraw(void)
{
   GLfloat w = 1.0;
   GLfloat h = 1.0;

   glClear( GL_COLOR_BUFFER_BIT );

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

   glPushMatrix();
   glTranslatef(-1.5, 0, -Zpos);
      glBegin(GL_POLYGON);
      glTexCoord2f(0, 0);  glVertex2f(-w, -h);
      glTexCoord2f(1, 0);  glVertex2f( w, -h);
      glTexCoord2f(1, 1);  glVertex2f( w,  h);
      glTexCoord2f(0, 1);  glVertex2f(-w,  h);
      glEnd();
   glPopMatrix();

   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

   glPushMatrix();
   glTranslatef(1.5, 0, -Zpos);
      glBegin(GL_POLYGON);
      glTexCoord2f(0, 0);  glVertex2f(-w, -h);
      glTexCoord2f(1, 0);  glVertex2f( w, -h);
      glTexCoord2f(1, 1);  glVertex2f( w,  h);
      glTexCoord2f(0, 1);  glVertex2f(-w,  h);
      glEnd();
   glPopMatrix();

   glutSwapBuffers();
}


static void
init(void)
{
   GLubyte color[10][4] = {
      { 0, 0, 0, 0 },
      { 1, 0, 0, 0 },
      { 0, 1, 0, 0 },
      { 0, 0, 1, 0 },
      { 0, 1, 1, 0 },
      { 1, 0, 1, 0 },
      { 1, 1, 0, 0 },
      { 1, 0, 0, 0 },
      { 0, 1, 0, 0 },
      { 0, 0, 1, 0 }
   };
   GLubyte *texImage;

   printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
   printf("Left quad should be linear filtered and right should be nearest filtered.\n");
   printf("Press z/Z to change quad distance.\n");

   texImage = (GLubyte*) malloc(4 * TexWidth * TexHeight * sizeof(GLubyte));
   assert(texImage);

   {
      GLint level = 0;
      GLint w = TexWidth, h = TexHeight;
      while (1) {
         int i, j;

         for (i = 0; i < h; i++) {
            for (j = 0;j < w; j++) {
               if (w==1 || h==1 || (((i / 2) ^ (j / 2)) & 1)) {
                  /*if (j < i) {*/
                  texImage[(i*w+j) * 4 + 0] = 255;
                  texImage[(i*w+j) * 4 + 1] = 255;
                  texImage[(i*w+j) * 4 + 2] = 255;
                  texImage[(i*w+j) * 4 + 3] = 255;
               }
               else {
                  texImage[(i*w+j) * 4 + 0] = color[level][0] * 255;
                  texImage[(i*w+j) * 4 + 1] = color[level][1] * 255;
                  texImage[(i*w+j) * 4 + 2] = color[level][2] * 255;
                  texImage[(i*w+j) * 4 + 3] = color[level][3] * 255;
               }
            }
         }

         glTexImage2D(GL_TEXTURE_2D, level, GL_RGBA8, w, h, 0,
                      GL_RGBA, GL_UNSIGNED_BYTE, texImage);

         printf("Texture level %d: %d x %d\n", level, w, h);
         if (!MipMap)
            break;

         if (w == 1 && h == 1)
            break;
         if (w > 1)
            w /= 2;
         if (h > 1)
            h /= 2;
         level++;
      }
   }

   free(texImage);

   glClearColor(0.25, 0.25, 0.25, 1.0);
   glEnable(GL_TEXTURE_2D);

   glViewport(0, 0, Width, Height);
}



static void
Reshape(int width, int height)
{
   float ar = (float) width /height;
   Width = width;
   Height = height;
   glViewport(0, 0, width, height);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glFrustum(-ar, ar, -1.0, 1.0, 5.0, 2500.0);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
   glTranslatef(0.0, 0.0, -15.0);
}


static void
Key(unsigned char key, int x, int y)
{
   (void) x;
   (void) y;
   switch (key) {
   case 'z':
      Zpos--;
      break;
   case 'Z':
      Zpos++;
      break;
   case 'f':
      LinearFilter = !LinearFilter;
      break;
   case 27:
      exit(0);
      break;
   }
   glutPostRedisplay();
}


int
main(int argc, char *argv[])
{
   glutInit(&argc, argv);
   glutInitWindowPosition(0, 0);
   glutInitWindowSize(Width, Height);
   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
   glutCreateWindow(argv[0]);
   glewInit();
   glutReshapeFunc(Reshape);
   glutKeyboardFunc(Key);
   glutDisplayFunc(redraw);
   init();
   glutMainLoop();
   return 0;
}