use GL_NEAREST texture filter

progs/demos/texenv.c

@@ -548,8 +548,8 @@ static void drawSample( int x, int y, int w, int h,
    glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, envMode->mode );
    glTexEnvfv( GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, envColors[envColor] );
 
-   glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
-   glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
+   glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
+   glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
 
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP );
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP );