shithub: qk1

ref: e92454e8739ee80d9ae080d4abd76f0b6f6d4034
dir: /r_fog.c/

#include "quakedef.h"

static cvar_t r_fog = {"r_fog", "1", true};
static cvar_t r_skyfog = {"r_skyfog", "0.5"};

static struct {
	float density;
	pixel_t color;
	byte c0, c1, c2;
}r_fog_data;

static void
fog(void)
{
	int i, j, n;
	float x;

	i = 1;
	n = Cmd_Argc();
	switch(n){
	case 5:
	case 2:
		x = atof(Cmd_Argv(i++));
		r_fog_data.density = clamp(x, 0.0, 1.0) * 0.016;
		r_fog_data.density *= r_fog_data.density;
		if(n == 2)
			break;
	case 4:
		r_fog_data.color = 0;
		for(j = 0; j < 3; j++, i++){
			x = atof(Cmd_Argv(i));
			r_fog_data.color = r_fog_data.color << 8 | (int)(0xff * clamp(x, 0.0, 1.0));
		}
		r_fog_data.c0 = r_fog_data.color>> 0;
		r_fog_data.c1 = r_fog_data.color>> 8;
		r_fog_data.c2 = r_fog_data.color>>16;
		break;
	}
}

void
R_ResetFog(void)
{
	r_fog_data.density = 0;
	r_fog_data.color = 0x808080;
	r_fog_data.c0 = r_fog_data.c1 = r_fog_data.c2 = 0x80;
	setcvar("r_skyfog", "0");
}

pixel_t
R_BlendFog(pixel_t pix, uzint z)
{
	byte a;
	float d;

	if(r_fog.value <= 0 || r_fog_data.density <= 0.0)
		return pix;

	if(z > 65536){
		d = 65536ULL*65536ULL / (u64int)z;
		if((pix & ~0xffffff) == 0)
			d /= 1.5;
		d = 1.0 - exp2(-r_fog_data.density * d*d);
		a = 255*d;
	}else if(z < 0){
		a = 255 * clamp(r_skyfog.value, 0, 1.0);
	}else
		a = 0;

	if(a == 0)
		return pix;

	return
		((a*r_fog_data.c0 + (255-a)*((pix>> 0)&0xff)) >> 8) << 0 |
		((a*r_fog_data.c1 + (255-a)*((pix>> 8)&0xff)) >> 8) << 8 |
		((a*r_fog_data.c2 + (255-a)*((pix>>16)&0xff)) >> 8) << 16;
}

void
R_DrawFog(void)
{
	pixel_t *pix;
	int i, x, y;
	uzint *z;

	if(r_fog.value <= 0 || r_fog_data.density <= 0.0)
		return;

	/* FIXME(sigrid): this is super slow */
	for(y = r_refdef.vrect.y; y < r_refdef.vrectbottom; y++){
		i = y * vid.width + r_refdef.vrect.x;
		pix = vid.buffer + i;
		z = d_pzbuffer + i;
		for(x = r_refdef.vrect.x; x < r_refdef.vrectright; x++, i++, pix++, z++)
			*pix = R_BlendFog(*pix, *z);
	}
}

void
R_InitFog(void)
{
	Cmd_AddCommand("fog", fog);
	Cvar_RegisterVariable(&r_fog);
	Cvar_RegisterVariable(&r_skyfog);
}