Qrack's "Nightmare mode"

[Baker]

Qrack's gl_nightmaremode does a couple of things, one of which is turns the world to shades of gray. I haven't looked, but my guess is that it converts world textures (world texture = textures that are part of the map) to black and white.

I remember last year when GoldQuake emulated the DOS feature of the tinted palette, Spike mentioning something about FTEQW doing about the same using a shader.

Anyway, is there a way to manipulate the color buffer to gray scale it or even "gray scale + green it" (a night vision type of effect). Just wondering since I can't think of any blending function that would achieve that.

OpenGL documentation in my opinion sucks, maybe the biggest liability of the graphics api is that since the documentation sucks you have to rely on stuff like Nehe tutorials and Google and I find myself using MSDN docs. (I imagine Direct3D has very high quality documentation like anything Microsoft does).

[r00k]

Actually all its doing is a fullscreen gl_quad with a call to
glCopyTexImage2D.

Depending on your format you can get a varied effect...
I've changed it to be "RED" ala "PainKiller"

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glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RED, glx, gly, vwidth, vheight, 0);

I think the grey was GL_LUMINANCE or GL_LUMINANCE_ALPHA

To answer your question yes, GL_GREEN..

This is the motion blur code that is used for gl_nightmare...

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void R_RenderSceneBlur (float alpha, GLenum format)
{
   extern int   sceneblur_texture;
   int vwidth = 2, vheight = 2;
   float vs, vt;

   if (alpha < 0.1)
      alpha = 0.1;

   while (vwidth < glwidth)
   {
      vwidth *= 2;
   }
   while (vheight < glheight)
   {
      vheight *= 2;
   }

   glViewport (glx, gly, glwidth, glheight);

   GL_Bind(sceneblur_texture);

   // go 2d
   glMatrixMode(GL_PROJECTION);
   glPushMatrix();
   glLoadIdentity ();
   glOrtho  (0, glwidth, 0, glheight, -99999, 99999);
   glMatrixMode(GL_MODELVIEW);
   glPushMatrix();
   glLoadIdentity ();

   vs = ((float)glwidth / vwidth);
   vt = ((float)glheight / vheight) ;

   glDisable (GL_DEPTH_TEST);
   glDisable (GL_CULL_FACE);
   glEnable(GL_BLEND);

   glColor4f(1, 1, 1, alpha);//<-- alpha of blur     

   glBegin(GL_QUADS);
      glTexCoord2f(0, 0);
      glVertex2f(0, 0);
      glTexCoord2f(vs , 0);
      glVertex2f(glwidth, 0);
      glTexCoord2f(vs , vt);
      glVertex2f(glwidth, glheight);
      glTexCoord2f(0, vt);
      glVertex2f(0, glheight);
   glEnd();

   glEnable(GL_DEPTH_TEST);
   glDepthMask(1);
   glColor3f (1,1,1);   
    glDisable (GL_BLEND);   

   glMatrixMode(GL_PROJECTION);
   glPopMatrix();      
   glMatrixMode(GL_MODELVIEW);
   glPopMatrix();      

   glCopyTexImage2D(GL_TEXTURE_2D, 0, format, glx, gly, vwidth, vheight, 0);

//   glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);        
}


and the call

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         if ((cl.items & IT_INVULNERABILITY)&&(gl_nightmare.value))
         {
            R_RenderSceneBlur (gl_nightmare.value, GL_RED);
         }


There would be a more elegant way of doing this though with a shader. Plus to allow entities to glow a bright yellow when viewed with the night vision goggles.

[mh]

glColorMask.