/*
Copyright (C) 1996-2001 Id Software, Inc.
Copyright (C) 2002-2009 John Fitzgibbons and others
Copyright (C) 2010-2014 QuakeSpasm developers

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/
// r_light.c

#include "q_defs.h"

int32_t r_dlightframecount;

extern cvar_t r_flatlightstyles; //johnfitz

/*
==================
R_AnimateLight
==================
*/
void R_AnimateLight(void)
{
	int32_t                 i, j, k;

//
// light animations
// 'm' is normal light, 'a' is no light, 'z' is double bright
	i = (int32_t)(cl.time * 10);
	for(j = 0 ; j < MAX_LIGHTSTYLES ; j++)
	{
		if(!cl_lightstyle[j].length)
		{
			d_lightstylevalue[j] = 256;
			continue;
		}
		//johnfitz -- r_flatlightstyles
		if(r_flatlightstyles.value == 2)
			k = cl_lightstyle[j].peak - 'a';
		else if(r_flatlightstyles.value == 1)
			k = cl_lightstyle[j].average - 'a';
		else
		{
			k = i % cl_lightstyle[j].length;
			k = cl_lightstyle[j].map[k] - 'a';
		}
		d_lightstylevalue[j] = k * 22;
		//johnfitz
	}
}

/*
=============================================================================

DYNAMIC LIGHTS BLEND RENDERING (gl_flashblend 1)

=============================================================================
*/

void AddLightBlend(float r, float g, float b, float a2)
{
	float   a;

	v_blend[3] = a = v_blend[3] + a2 * (1 - v_blend[3]);

	a2 = a2 / a;

	v_blend[0] = v_blend[1] * (1 - a2) + r * a2;
	v_blend[1] = v_blend[1] * (1 - a2) + g * a2;
	v_blend[2] = v_blend[2] * (1 - a2) + b * a2;
}

void R_RenderDlight(dlight_t *light)
{
	int32_t         i, j;
	float   a;
	vec3_t  v;
	float   rad;

	rad = light->radius * 0.35;

	VectorSubtract(light->origin, r_origin, v);
	if(VectorLength(v) < rad)
	{
		// view is inside the dlight
		AddLightBlend(1, 0.5, 0, light->radius * 0.0003);
		return;
	}

	glBegin(GL_TRIANGLE_FAN);
	glColor3f(0.2, 0.1, 0.0);
	for(i = 0 ; i < 3 ; i++)
		v[i] = light->origin[i] - vpn[i] * rad;
	glVertex3fv(v);
	glColor3f(0, 0, 0);
	for(i = 16 ; i >= 0 ; i--)
	{
		a = i / 16.0 * PI * 2;
		for(j = 0 ; j < 3 ; j++)
			v[j] = light->origin[j] + vright[j] * cos(a) * rad
			       + vup[j] * sin(a) * rad;
		glVertex3fv(v);
	}
	glEnd();
}

/*
=============
R_RenderDlights
=============
*/
void R_RenderDlights(void)
{
	int32_t         i;
	dlight_t        *l;

	if(!gl_flashblend.value)
		return;

	r_dlightframecount = r_framecount + 1;  // because the count hasn't
	//  advanced yet for this frame
	glDepthMask(0);
	glDisable(GL_TEXTURE_2D);
	glShadeModel(GL_SMOOTH);
	glEnable(GL_BLEND);
	glBlendFunc(GL_ONE, GL_ONE);

	l = cl_dlights;
	for(i = 0 ; i < cl_max_dlights ; i++, l++)
	{
		if(l->die < cl.time || !l->radius)
			continue;
		R_RenderDlight(l);
	}

	glColor3f(1, 1, 1);
	glDisable(GL_BLEND);
	glEnable(GL_TEXTURE_2D);
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glDepthMask(1);
}


/*
=============================================================================

DYNAMIC LIGHTS

=============================================================================
*/

/*
=============
R_MarkLights -- johnfitz -- rewritten to use LordHavoc's lighting speedup
=============
*/
void R_MarkLights(dlight_t *light, int32_t num, mnode_t *node)
{
	mplane_t        *splitplane;
	msurface_t      *surf;
	vec3_t          impact;
	float           dist, l, maxdist;
	int32_t                 i, j, s, t;

start:

	if(node->contents < 0)
		return;

	splitplane = node->plane;
	if(splitplane->type < 3)
		dist = light->origin[splitplane->type] - splitplane->dist;
	else
		dist = DotProduct(light->origin, splitplane->normal) - splitplane->dist;

	if(dist > light->radius)
	{
		node = node->children[0];
		goto start;
	}
	if(dist < -light->radius)
	{
		node = node->children[1];
		goto start;
	}

	maxdist = light->radius * light->radius;
// mark the polygons
	surf = cl.worldmodel->surfaces + node->firstsurface;
	for(i = 0 ; i < node->numsurfaces ; i++, surf++)
	{
		for(j = 0 ; j < 3 ; j++)
			impact[j] = light->origin[j] - surf->plane->normal[j] * dist;
		// clamp center of light to corner and check brightness
		l = DotProduct(impact, surf->texinfo->vecs[0]) + surf->texinfo->vecs[0][3] - surf->texturemins[0];
		s = l + 0.5;
		if(s < 0) s = 0;
		else if(s > surf->extents[0]) s = surf->extents[0];
		s = l - s;
		l = DotProduct(impact, surf->texinfo->vecs[1]) + surf->texinfo->vecs[1][3] - surf->texturemins[1];
		t = l + 0.5;
		if(t < 0) t = 0;
		else if(t > surf->extents[1]) t = surf->extents[1];
		t = l - t;
		// compare to minimum light
		if((s * s + t * t + dist * dist) < maxdist)
		{
			if(surf->dlightframe != r_dlightframecount)  // not dynamic until now
			{
				surf->dlightbits[num >> 5] = 1U << (num & 31);
				surf->dlightframe = r_dlightframecount;
			}
			else // already dynamic
				surf->dlightbits[num >> 5] |= 1U << (num & 31);
		}
	}

	if(node->children[0]->contents >= 0)
		R_MarkLights(light, num, node->children[0]);
	if(node->children[1]->contents >= 0)
		R_MarkLights(light, num, node->children[1]);
}

/*
=============
R_PushDlights
=============
*/
void R_PushDlights(void)
{
	int32_t         i;
	dlight_t        *l;

	if(gl_flashblend.value)
		return;

	r_dlightframecount = r_framecount + 1;  // because the count hasn't
	//  advanced yet for this frame
	l = cl_dlights;

	for(i = 0 ; i < cl_max_dlights ; i++, l++)
	{
		if(l->die < cl.time || !l->radius)
			continue;
		R_MarkLights(l, i, cl.worldmodel->nodes);
	}
}


/*
=============================================================================

LIGHT SAMPLING

=============================================================================
*/

mplane_t                *lightplane;
vec3_t                  lightspot;
vec3_t                  lightcolor; //johnfitz -- lit support via lordhavoc

/*
=============
RecursiveLightPoint -- johnfitz -- replaced entire function for lit support via lordhavoc
=============
*/
int32_t RecursiveLightPoint(vec3_t color, mnode_t *node, vec3_t start, vec3_t end)
{
	float           front, back, frac;
	vec3_t          mid;

loc0:
	if(node->contents < 0)
		return false;           // didn't hit anything

// calculate mid point
	if(node->plane->type < 3)
	{
		front = start[node->plane->type] - node->plane->dist;
		back = end[node->plane->type] - node->plane->dist;
	}
	else
	{
		front = DotProduct(start, node->plane->normal) - node->plane->dist;
		back = DotProduct(end, node->plane->normal) - node->plane->dist;
	}

	// LordHavoc: optimized recursion
	if((back < 0) == (front < 0))
//		return RecursiveLightPoint (color, node->children[front < 0], start, end);
	{
		node = node->children[front < 0];
		goto loc0;
	}

	frac = front / (front - back);
	mid[0] = start[0] + (end[0] - start[0]) * frac;
	mid[1] = start[1] + (end[1] - start[1]) * frac;
	mid[2] = start[2] + (end[2] - start[2]) * frac;

// go down front side
	if(RecursiveLightPoint(color, node->children[front < 0], start, mid))
		return true;    // hit something
	else
	{
		int32_t i, ds, dt;
		msurface_t *surf;
		// check for impact on this node
		VectorCopy(mid, lightspot);
		lightplane = node->plane;

		surf = cl.worldmodel->surfaces + node->firstsurface;
		for(i = 0; i < node->numsurfaces; i++, surf++)
		{
			if(surf->flags & SURF_DRAWTILED)
				continue;       // no lightmaps

			// ericw -- added double casts to force 64-bit precision.
			// Without them the zombie at the start of jam3_ericw.bsp was
			// incorrectly being lit up in SSE builds.
			ds = (int32_t)((double) DoublePrecisionDotProduct(mid, surf->texinfo->vecs[0]) + surf->texinfo->vecs[0][3]);
			dt = (int32_t)((double) DoublePrecisionDotProduct(mid, surf->texinfo->vecs[1]) + surf->texinfo->vecs[1][3]);

			if(ds < surf->texturemins[0] || dt < surf->texturemins[1])
				continue;

			ds -= surf->texturemins[0];
			dt -= surf->texturemins[1];

			if(ds > surf->extents[0] || dt > surf->extents[1])
				continue;

			if(surf->samples)
			{
				// LordHavoc: enhanced to interpolate lighting
				byte *lightmap;
				int32_t maps, line3, dsfrac = ds & 15, dtfrac = dt & 15, r00 = 0, g00 = 0, b00 = 0, r01 = 0, g01 = 0, b01 = 0, r10 = 0, g10 = 0, b10 = 0, r11 = 0, g11 = 0, b11 = 0;
				float scale;
				line3 = ((surf->extents[0] >> 4) + 1) * 3;

				lightmap = surf->samples + ((dt >> 4) * ((surf->extents[0] >> 4) + 1) + (ds >> 4)) * 3; // LordHavoc: *3 for color

				for(maps = 0; maps < MAXLIGHTMAPS && surf->styles[maps] != 255; maps++)
				{
					scale = (float) d_lightstylevalue[surf->styles[maps]] * 1.0 / 256.0;
					r00 += (float) lightmap[      0] * scale;
					g00 += (float) lightmap[      1] * scale;
					b00 += (float) lightmap[2] * scale;
					r01 += (float) lightmap[      3] * scale;
					g01 += (float) lightmap[      4] * scale;
					b01 += (float) lightmap[5] * scale;
					r10 += (float) lightmap[line3 + 0] * scale;
					g10 += (float) lightmap[line3 + 1] * scale;
					b10 += (float) lightmap[line3 + 2] * scale;
					r11 += (float) lightmap[line3 + 3] * scale;
					g11 += (float) lightmap[line3 + 4] * scale;
					b11 += (float) lightmap[line3 + 5] * scale;
					lightmap += ((surf->extents[0] >> 4) + 1) * ((surf->extents[1] >> 4) + 1) * 3; // LordHavoc: *3 for colored lighting
				}

				color[0] += (float)((int32_t)((((((((r11 - r10) * dsfrac) >> 4) + r10) - ((((r01 - r00) * dsfrac) >> 4) + r00)) * dtfrac) >> 4) + ((((r01 - r00) * dsfrac) >> 4) + r00)));
				color[1] += (float)((int32_t)((((((((g11 - g10) * dsfrac) >> 4) + g10) - ((((g01 - g00) * dsfrac) >> 4) + g00)) * dtfrac) >> 4) + ((((g01 - g00) * dsfrac) >> 4) + g00)));
				color[2] += (float)((int32_t)((((((((b11 - b10) * dsfrac) >> 4) + b10) - ((((b01 - b00) * dsfrac) >> 4) + b00)) * dtfrac) >> 4) + ((((b01 - b00) * dsfrac) >> 4) + b00)));
			}
			return true; // success
		}

		// go down back side
		return RecursiveLightPoint(color, node->children[front >= 0], mid, end);
	}
}

/*
=============
R_LightPoint -- johnfitz -- replaced entire function for lit support via lordhavoc
=============
*/
int32_t R_LightPoint(vec3_t p)
{
	vec3_t          end;

	if(!cl.worldmodel->lightdata)
	{
		lightcolor[0] = lightcolor[1] = lightcolor[2] = 255;
		return 255;
	}

	end[0] = p[0];
	end[1] = p[1];
	end[2] = p[2] - 8192; //johnfitz -- was 2048

	lightcolor[0] = lightcolor[1] = lightcolor[2] = 0;
	RecursiveLightPoint(lightcolor, cl.worldmodel->nodes, p, end);
	return ((lightcolor[0] + lightcolor[1] + lightcolor[2]) * (1.0f / 3.0f));
}