Quake Motion Blur

[mh]

This somewhere in gl_rmain.c:

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extern cvar_t r_motionblur;

void DrawAccumBlur (void)
{
   static int blurstate = 0;
   float accblur;
   static float damagetime = -1.0f;

   if (!r_motionblur.value) return;

   // evaluate blur conditions
   if (cl.stats[STAT_HEALTH] <= 0)
   {
      // being dead always overrides everything else
      accblur = 0.75f;
   }
   else if (cl.cshifts[CSHIFT_DAMAGE].percent)
   {
      // initial damage blur
      accblur = 0.75f;
      damagetime = 0.5f;
   }
   else if (damagetime >= 0.0f)
   {
      // persist damage blur
      damagetime -= r_frametime;
      accblur = 0.75f;
   }
   else if (cl.cshifts[CSHIFT_CONTENTS].percent)
   {
      // blur less if underwater
      accblur = 0.666f;
   }
   else accblur = -1.0f;

   if (accblur <= 0.0f)
   {
      // reinit if we're not blurring so that the contents of the
      // accumulation buffer are valid for the frame
      blurstate = 0;
      return;
   }

   if (!blurstate)
   {
      // load the scene into the accumulation buffer
      glAccum (GL_LOAD, 1.0f);
   }
   else
   {
      glAccum (GL_MULT, accblur); // scale contents of accumulation buffer
      glAccum (GL_ACCUM, 1.0f - accblur); // add screen contents
      glAccum (GL_RETURN, 1.0f); // read result back
   }

   blurstate = 1;
}

(Declare and register the r_motionblur cvar somewhere too, and you may also need to have a global called r_frametime, so just set it up the same way as frametime in R_DrawParticles...)

Call it like this, at the end of R_RenderView, after everything else is drawn:

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   // draw motion blur effects on the full 3D view
   DrawAccumBlur ();

Finally, in gl_vidnt.c, when setting up your PIXELFORMATDESCRIPTOR, just set the cAccumBits member to 64.

There's no need to clear the accumulation buffer between frames, should work just fine on any engine out of the box.

[MeTcHsteekle]

sweet

[leileilol]

Just chiming in that this can also be applied to Q3A as well (though replacing the whole stat/damage checking with some variable framerate smoothing thing, since you can't access player stats from the renderer module anyway).

Thanks!

[r00k]

works!

[leileilol]

By the way and FYI - accumulation buffers in consumer videogaming video hardware only begin their support starting from shader model 2.0 hardware, despite this predating the whole programmable shader thing for ages.

[toneddu2000]

I can't understand the last step.

Finally, in gl_vidnt.c, when setting up your PIXELFORMATDESCRIPTOR, just set the cAccumBits member to 64.

I use quakespasm and there's no gl_vidnt.c but gl_vidsdl.c. I hope it's the same. Now what should I set?
thanks

[hogsy]

Rather than doing that I'd suppose you'd set the following in the case of SDL.

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SDL_GL_SetAttribute(SDL_GL_ACCUM_RED_SIZE,8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_GREEN_SIZE,8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_BLUE_SIZE,8);
SDL_GL_SetAttribute(SDL_GL_ACCUM_ALPHA_SIZE,8);


[toneddu2000]

thanks hogsy but where should I put those functions?

[hogsy]

I haven't touched QuakeSpasm but if you take a look in gl_vidsdl there should be a bunch of the same functions where the SDL window is created and you can just plop it in with those, shouldn't be too hard to find if you just do a quick search

[toneddu2000]

the only SDL_GL_SetAttribute() function I found it's in VID_SetMode () int gl_vidsdl.c and it's called like this:

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if (SDL_GL_SetAttribute(SDL_GL_SWAP_CONTROL, (vid_vsync.value) ? 1 : 0) == -1)
      gl_swap_control = false;

There's no bunch of SDL functions

thanks

[hogsy]

Just plop it under those two lines then.

[toneddu2000]

It worked! Thanks a lot hogsy and of course mh for this great addition!

For the QuakeSpasm lovers:
declare at the start of the gl_rmain.c

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float  r_frametime;

put at the start of the DrawAccumBlur() function

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r_frametime = cl.time - cl.oldtime;


in gl_vidsdl.c, in VID_SetMode function,after:

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if (SDL_GL_SetAttribute(SDL_GL_SWAP_CONTROL, (vid_vsync.value) ? 1 : 0) == -1)
      gl_swap_control = false;

put those lines as hogsy stated

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SDL_GL_SetAttribute(SDL_GL_ACCUM_RED_SIZE, 8);
   SDL_GL_SetAttribute(SDL_GL_ACCUM_GREEN_SIZE, 8);
   SDL_GL_SetAttribute(SDL_GL_ACCUM_BLUE_SIZE, 8);
   SDL_GL_SetAttribute(SDL_GL_ACCUM_ALPHA_SIZE, 8);

I avoided the

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if (!r_motionblur.value) return;

line because I still didn't understand how send the cvars to quakec, so in my case motion blur is on by default.

There's a chance to mimic that cool Doom3 pain rotating head effect?

[leileilol]

You could do something derivative of v_idlescale in view.c to make that scale from damagetime.

[toneddu2000]

thanks leilei, I tried in V_AddIdle:

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void V_AddIdle (void)
{
   r_refdef.viewangles[ROLL] += v_idlescale.value * sin(cl.time*v_iroll_cycle.value) * v_iroll_level.value;
   r_refdef.viewangles[PITCH] += v_idlescale.value * sin(cl.time*v_ipitch_cycle.value) * v_ipitch_level.value;
   r_refdef.viewangles[YAW] += v_idlescale.value * sin(cl.time*v_iyaw_cycle.value) * v_iyaw_level.value;
   //code below added by me
   if (cl.cshifts[CSHIFT_DAMAGE].percent)
   {
      cl.viewent.angles[ROLL] -= v_idlescale.value * 250.0f;
      cl.viewent.angles[PITCH] -= v_idlescale.value * 250.0f;
      cl.viewent.angles[YAW] -= v_idlescale.value * 250.0f;
   }
}


Then I set cvar r_idlescale to 1 but nothing. I exagerated roll,pitch and yaw movements to maximum just to test if it could work but it doesn't do anything

[leileilol]

Because you have to alter the refdef's angles not the viewent itself. IIRC, viewent is the gun. The gun gets its origin and angles calculated in another function that comes after addidle. iirc