#include "engine.h"

struct decalvert
{
	vec pos;
	bvec4 color;
	vec2 tc;
};

struct decalinfo
{
	int millis;
	bvec color;
	ushort startvert, endvert;
};

enum
{
	DF_RND4	   = 1<<0,
	DF_ROTATE	 = 1<<1,
	DF_INVMOD	 = 1<<2,
	DF_OVERBRIGHT = 1<<3,
	DF_ADD		= 1<<4,
	DF_SATURATE   = 1<<5
};

VARFP(maxdecaltris, 1, 1024, 16384, initdecals());
VARP(decalfade, 1000, 10000, 60000);

struct decalrenderer
{
	const char *texname;
	int flags, fadeintime, fadeouttime, timetolive;
	Texture *tex;
	decalinfo *decals;
	int maxdecals, startdecal, enddecal;
	decalvert *verts;
	int maxverts, startvert, endvert, lastvert, availverts;
	GLuint vbo;
	bool dirty;

	decalrenderer(const char *texname, int flags = 0, int fadeintime = 0, int fadeouttime = 1000, int timetolive = -1)
		: texname(texname), flags(flags),
		  fadeintime(fadeintime), fadeouttime(fadeouttime), timetolive(timetolive),
		  tex(NULL),
		  decals(NULL), maxdecals(0), startdecal(0), enddecal(0),
		  verts(NULL), maxverts(0), startvert(0), endvert(0), lastvert(0), availverts(0),
		  vbo(0), dirty(false),
		  decalu(0), decalv(0)
	{
	}

	~decalrenderer()
	{
		DELETEA(decals);
		DELETEA(verts);
	}

	void init(int tris)
	{
		if(decals)
		{
			DELETEA(decals);
			maxdecals = startdecal = enddecal = 0;
		}
		if(verts)
		{
			DELETEA(verts);
			maxverts = startvert = endvert = lastvert = availverts = 0;
		}
		decals = new decalinfo[tris];
		maxdecals = tris;
		tex = textureload(texname, 3);
		maxverts = tris*3 + 3;
		availverts = maxverts - 3;
		verts = new decalvert[maxverts];
	}

	int hasdecals()
	{
		return enddecal < startdecal ? maxdecals - (startdecal - enddecal) : enddecal - startdecal;
	}

	void cleanup()
	{
		if(vbo) { glDeleteBuffers_(1, &vbo); vbo = 0; }
	}

	void cleardecals()
	{
		startdecal = enddecal = 0;
		startvert = endvert = lastvert = 0;
		availverts = maxverts - 3;
		dirty = true;
	}

	int freedecal()
	{
		if(startdecal==enddecal) return 0;

		decalinfo &d = decals[startdecal];
		startdecal++;
		if(startdecal >= maxdecals) startdecal = 0;

		int removed = d.endvert < d.startvert ? maxverts - (d.startvert - d.endvert) : d.endvert - d.startvert;
		startvert = d.endvert;
		if(startvert==endvert) startvert = endvert = lastvert = 0;
		availverts += removed;

		return removed;
	}

	void fadedecal(decalinfo &d, uchar alpha)
	{
		bvec rgb;
		if(flags&DF_OVERBRIGHT) rgb = bvec(128, 128, 128);
		else
		{
			rgb = d.color;
			if(flags&(DF_ADD|DF_INVMOD)) rgb.scale(alpha, 255);
		}
		bvec4 color(rgb, alpha);

		decalvert *vert = &verts[d.startvert],
				  *end = &verts[d.endvert < d.startvert ? maxverts : d.endvert];
		while(vert < end)
		{
			vert->color = color;
			vert++;
		}
		if(d.endvert < d.startvert)
		{
			vert = verts;
			end = &verts[d.endvert];
			while(vert < end)
			{
				vert->color = color;
				vert++;
			}
		}
		dirty = true;
	}

	void clearfadeddecals()
	{
		int threshold = lastmillis - (timetolive>=0 ? timetolive : decalfade) - fadeouttime;
		decalinfo *d = &decals[startdecal],
				  *end = &decals[enddecal < startdecal ? maxdecals : enddecal];
		while(d < end && d->millis <= threshold) d++;
		if(d >= end && enddecal < startdecal)
		{
			d = decals;
			end = &decals[enddecal];
			while(d < end && d->millis <= threshold) d++;
		}
		int prevstart = startdecal;
		startdecal = d - decals;
		if(prevstart == startdecal) return;
		if(startdecal!=enddecal) startvert = decals[startdecal].startvert;
		else startvert = endvert = lastvert = 0;
		availverts = endvert < startvert ? startvert - endvert - 3 : maxverts - 3 - (endvert - startvert);
		dirty = true;
	}

	void fadeindecals()
	{
		if(!fadeintime) return;
		decalinfo *d = &decals[enddecal],
				  *end = &decals[enddecal < startdecal ? 0 : startdecal];
		while(d > end)
		{
			d--;
			int fade = lastmillis - d->millis;
			if(fade >= fadeintime) return;
			fadedecal(*d, (fade<<8)/fadeintime);
		}
		if(enddecal < startdecal)
		{
			d = &decals[maxdecals];
			end = &decals[startdecal];
			while(d > end)
			{
				d--;
				int fade = lastmillis - d->millis;
				if(fade >= fadeintime) return;
				fadedecal(*d, (fade<<8)/fadeintime);
			}
		}
	}

	void fadeoutdecals()
	{
		decalinfo *d = &decals[startdecal],
				  *end = &decals[enddecal < startdecal ? maxdecals : enddecal];
		int offset = (timetolive>=0 ? timetolive : decalfade) + fadeouttime - lastmillis;
		while(d < end)
		{
			int fade = d->millis + offset;
			if(fade >= fadeouttime) return;
			fadedecal(*d, (fade<<8)/fadeouttime);
			d++;
		}
		if(enddecal < startdecal)
		{
			d = decals;
			end = &decals[enddecal];
			while(d < end)
			{
				int fade = d->millis + offset;
				if(fade >= fadeouttime) return;
				fadedecal(*d, (fade<<8)/fadeouttime);
				d++;
			}
		}
	}

	static void setuprenderstate()
	{
		enablepolygonoffset(GL_POLYGON_OFFSET_FILL);

		glDepthMask(GL_FALSE);
		glEnable(GL_BLEND);

		gle::enablevertex();
		gle::enabletexcoord0();
		gle::enablecolor();
	}

	static void cleanuprenderstate()
	{
		gle::clearvbo();

		gle::disablevertex();
		gle::disabletexcoord0();
		gle::disablecolor();

		glDepthMask(GL_TRUE);
		glDisable(GL_BLEND);

		disablepolygonoffset(GL_POLYGON_OFFSET_FILL);
	}

	void render()
	{
		if(startvert==endvert) return;

		if(flags&DF_OVERBRIGHT)
		{
			glBlendFunc(GL_DST_COLOR, GL_SRC_COLOR);
			SETSHADER(overbrightdecal);
		}
		else
		{
			if(flags&DF_INVMOD) { glBlendFunc(GL_ZERO, GL_ONE_MINUS_SRC_COLOR); }
			else if(flags&DF_ADD) { glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_COLOR); }
			else glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

			if(flags&DF_SATURATE) SETSHADER(saturatedecal);
		}

		glBindTexture(GL_TEXTURE_2D, tex->id);

		if(!vbo) { glGenBuffers_(1, &vbo); dirty = true; }
		gle::bindvbo(vbo);

		int count = endvert < startvert ? maxverts - startvert : endvert - startvert;
		if(dirty)
		{
			glBufferData_(GL_ARRAY_BUFFER, maxverts*sizeof(decalvert), NULL, GL_STREAM_DRAW);
			glBufferSubData_(GL_ARRAY_BUFFER, 0, count*sizeof(decalvert), &verts[startvert]);
			if(endvert < startvert)
			{
				glBufferSubData_(GL_ARRAY_BUFFER, count*sizeof(decalvert), endvert*sizeof(decalvert), verts);
				count += endvert;
			}
			dirty = false;
		}
		else if(endvert < startvert) count += endvert;

		const decalvert *ptr = 0;
		gle::vertexpointer(sizeof(decalvert), ptr->pos.v);
		gle::texcoord0pointer(sizeof(decalvert), ptr->tc.v);
		gle::colorpointer(sizeof(decalvert), ptr->color.v);

		glDrawArrays(GL_TRIANGLES, 0, count);
		xtravertsva += count;

		extern int intel_vertexarray_bug;
		if(intel_vertexarray_bug) glFlush();
	}

	decalinfo &newdecal()
	{
		decalinfo &d = decals[enddecal];
		int next = enddecal + 1;
		if(next>=maxdecals) next = 0;
		if(next==startdecal) freedecal();
		enddecal = next;
		dirty = true;
		return d;
	}

	ivec bbmin, bbmax;
	vec decalcenter, decalnormal, decaltangent, decalbitangent;
	float decalradius, decalu, decalv;
	bvec4 decalcolor;

	void adddecal(const vec &center, const vec &dir, float radius, const bvec &color, int info)
	{
		if(dir.iszero()) return;

		int bbradius = int(ceil(radius));
		bbmin = ivec(center).sub(bbradius);
		bbmax = ivec(center).add(bbradius);

		decalcolor = bvec4(color, 255);
		decalcenter = center;
		decalradius = radius;
		decalnormal = dir;
#if 0
		decaltangent.orthogonal(dir);
#else
		decaltangent = vec(dir.z, -dir.x, dir.y);
		decaltangent.sub(vec(dir).mul(decaltangent.dot(dir)));
#endif
		if(flags&DF_ROTATE) decaltangent.rotate(rnd(360)*RAD, dir);
		decaltangent.normalize();
		decalbitangent.cross(decaltangent, dir);
		if(flags&DF_RND4)
		{
			decalu = 0.5f*(info&1);
			decalv = 0.5f*((info>>1)&1);
		}

		lastvert = endvert;
		gentris(worldroot, ivec(0, 0, 0), worldsize>>1);
		if(endvert==lastvert) return;

		decalinfo &d = newdecal();
		d.color = color;
		d.millis = lastmillis;
		d.startvert = lastvert;
		d.endvert = endvert;
	}

	static int clip(const vec *in, int numin, const vec &dir, float below, float above, vec *out)
	{
		int numout = 0;
		const vec *p = &in[numin-1];
		float pc = dir.dot(*p);
		loopi(numin)
		{
			const vec &v = in[i];
			float c = dir.dot(v);
			if(c < below)
			{
				if(pc > above) out[numout++] = vec(*p).sub(v).mul((above - c)/(pc - c)).add(v);
				if(pc > below) out[numout++] = vec(*p).sub(v).mul((below - c)/(pc - c)).add(v);
			}
			else if(c > above)
			{
				if(pc < below) out[numout++] = vec(*p).sub(v).mul((below - c)/(pc - c)).add(v);
				if(pc < above) out[numout++] = vec(*p).sub(v).mul((above - c)/(pc - c)).add(v);
			}
			else
			{
				if(pc < below)
				{
					if(c > below) out[numout++] = vec(*p).sub(v).mul((below - c)/(pc - c)).add(v);
				}
				else if(pc > above && c < above) out[numout++] = vec(*p).sub(v).mul((above - c)/(pc - c)).add(v);
				out[numout++] = v;
			}
			p = &v;
			pc = c;
		}
		return numout;
	}

	void gentris(cube &cu, int orient, const ivec &o, int size, materialsurface *mat = NULL, int vismask = 0)
	{
		vec pos[MAXFACEVERTS+4] = { vec(0, 0, 0) };
		int numverts = 0, numplanes = 1;
		vec planes[2] = { vec(0, 0, 0) };
		if(mat)
		{
			planes[0] = vec(0, 0, 0);
			switch(orient)
			{
			#define GENFACEORIENT(orient, v0, v1, v2, v3) \
				case orient: \
					planes[0][dimension(orient)] = dimcoord(orient) ? 1 : -1; \
					v0 v1 v2 v3 \
					break;
			#define GENFACEVERT(orient, vert, x,y,z, xv,yv,zv) \
					pos[numverts++] = vec(x xv, y yv, z zv);
				GENFACEVERTS(o.x, o.x, o.y, o.y, o.z, o.z, , + mat->csize, , + mat->rsize, + 0.1f, - 0.1f);
			#undef GENFACEORIENT
			#undef GENFACEVERT
			}
		}
		else if(cu.texture[orient] == DEFAULT_SKY) return;
		else if(cu.ext && (numverts = cu.ext->surfaces[orient].numverts&MAXFACEVERTS))
		{
			vertinfo *verts = cu.ext->verts() + cu.ext->surfaces[orient].verts;
			ivec vo = ivec(o).mask(~0xFFF).shl(3);
			loopj(numverts) pos[j] = vec(verts[j].getxyz().add(vo)).mul(1/8.0f);
			planes[0].cross(pos[0], pos[1], pos[2]).normalize();
			if(numverts >= 4 && !(cu.merged&(1<<orient)) && !flataxisface(cu, orient) && faceconvexity(verts, numverts, size))
			{
				planes[1].cross(pos[0], pos[2], pos[3]).normalize();
				numplanes++;
			}
		}
		else if(cu.merged&(1<<orient)) return;
		else if(!vismask || (vismask&0x40 && visibleface(cu, orient, o, size, MAT_AIR, (cu.material&MAT_ALPHA)^MAT_ALPHA, MAT_ALPHA)))
		{
			ivec v[4];
			genfaceverts(cu, orient, v);
			int vis = 3, convex = faceconvexity(v, vis), order = convex < 0 ? 1 : 0;
			vec vo(o);
			pos[numverts++] = vec(v[order]).mul(size/8.0f).add(vo);
			if(vis&1) pos[numverts++] = vec(v[order+1]).mul(size/8.0f).add(vo);
			pos[numverts++] = vec(v[order+2]).mul(size/8.0f).add(vo);
			if(vis&2) pos[numverts++] = vec(v[(order+3)&3]).mul(size/8.0f).add(vo);
			planes[0].cross(pos[0], pos[1], pos[2]).normalize();
			if(convex) { planes[1].cross(pos[0], pos[2], pos[3]).normalize(); numplanes++; }
		}
		else return;

		loopl(numplanes)
		{
			const vec &n = planes[l];
			float facing = n.dot(decalnormal);
			if(facing <= 0) continue;
			vec p = vec(pos[0]).sub(decalcenter);
#if 0
			// intersect ray along decal normal with plane
			float dist = n.dot(p) / facing;
			if(fabs(dist) > decalradius) continue;
			vec pcenter = vec(decalnormal).mul(dist).add(decalcenter);
#else
			// travel back along plane normal from the decal center
			float dist = n.dot(p);
			if(fabs(dist) > decalradius) continue;
			vec pcenter = vec(n).mul(dist).add(decalcenter);
#endif
			vec ft, fb;
			ft.orthogonal(n);
			ft.normalize();
			fb.cross(ft, n);
			vec pt = vec(ft).mul(ft.dot(decaltangent)).add(vec(fb).mul(fb.dot(decaltangent))).normalize(),
				pb = vec(ft).mul(ft.dot(decalbitangent)).add(vec(fb).mul(fb.dot(decalbitangent))).normalize();
			// orthonormalize projected bitangent to prevent streaking
			pb.sub(vec(pt).mul(pt.dot(pb))).normalize();
			vec v1[MAXFACEVERTS+4], v2[MAXFACEVERTS+4];
			float ptc = pt.dot(pcenter), pbc = pb.dot(pcenter);
			int numv;
			if(numplanes >= 2)
			{
				if(l) { pos[1] = pos[2]; pos[2] = pos[3]; }
				numv = clip(pos, 3, pt, ptc - decalradius, ptc + decalradius, v1);
				if(numv<3) continue;
			}
			else
			{
				numv = clip(pos, numverts, pt, ptc - decalradius, ptc + decalradius, v1);
				if(numv<3) continue;
			}
			numv = clip(v1, numv, pb, pbc - decalradius, pbc + decalradius, v2);
			if(numv<3) continue;
			float tsz = flags&DF_RND4 ? 0.5f : 1.0f, scale = tsz*0.5f/decalradius,
				  tu = decalu + tsz*0.5f - ptc*scale, tv = decalv + tsz*0.5f - pbc*scale;
			pt.mul(scale); pb.mul(scale);
			decalvert dv1 = { v2[0], decalcolor, vec2(pt.dot(v2[0]) + tu, pb.dot(v2[0]) + tv) },
					  dv2 = { v2[1], decalcolor, vec2(pt.dot(v2[1]) + tu, pb.dot(v2[1]) + tv) };
			int totalverts = 3*(numv-2);
			if(totalverts > maxverts-3) return;
			while(availverts < totalverts)
			{
				if(!freedecal()) return;
			}
			availverts -= totalverts;
			loopk(numv-2)
			{
				verts[endvert++] = dv1;
				verts[endvert++] = dv2;
				dv2.pos = v2[k+2];
				dv2.tc = vec2(pt.dot(v2[k+2]) + tu, pb.dot(v2[k+2]) + tv);
				verts[endvert++] = dv2;
				if(endvert>=maxverts) endvert = 0;
			}
		}
	}

	void findmaterials(vtxarray *va)
	{
		materialsurface *matbuf = va->matbuf;
		int matsurfs = va->matsurfs;
		loopi(matsurfs)
		{
			materialsurface &m = matbuf[i];
			if(1) { i += m.skip; continue; }
			int dim = dimension(m.orient), dc = dimcoord(m.orient);
			if(dc ? decalnormal[dim] <= 0 : decalnormal[dim] >= 0) { i += m.skip; continue; }
			int c = C[dim], r = R[dim];
			for(;;)
			{
				materialsurface &m = matbuf[i];
				if(m.o[dim] >= bbmin[dim] && m.o[dim] <= bbmax[dim] &&
				   m.o[c] + m.csize >= bbmin[c] && m.o[c] <= bbmax[c] &&
				   m.o[r] + m.rsize >= bbmin[r] && m.o[r] <= bbmax[r])
				{
					static cube dummy;
					gentris(dummy, m.orient, m.o, max(m.csize, m.rsize), &m);
				}
				if(i+1 >= matsurfs) break;
				materialsurface &n = matbuf[i+1];
				if(n.material != m.material || n.orient != m.orient) break;
				i++;
			}
		}
	}

	void findescaped(cube *cu, const ivec &o, int size, int escaped)
	{
		loopi(8)
		{
			if(escaped&(1<<i))
			{
				ivec co(i, o, size);
				if(cu[i].children) findescaped(cu[i].children, co, size>>1, cu[i].escaped);
				else
				{
					int vismask = cu[i].merged;
					if(vismask) loopj(6) if(vismask&(1<<j)) gentris(cu[i], j, co, size);
				}
			}
		}
	}

	void gentris(cube *cu, const ivec &o, int size, int escaped = 0)
	{
		int overlap = octaboxoverlap(o, size, bbmin, bbmax);
		loopi(8)
		{
			if(overlap&(1<<i))
			{
				ivec co(i, o, size);
				if(cu[i].ext && cu[i].ext->va && cu[i].ext->va->matsurfs)
					findmaterials(cu[i].ext->va);
				if(cu[i].children) gentris(cu[i].children, co, size>>1, cu[i].escaped);
				else
				{
					int vismask = cu[i].visible;
					if(vismask&0xC0)
					{
						if(vismask&0x80) loopj(6) gentris(cu[i], j, co, size, NULL, vismask);
						else loopj(6) if(vismask&(1<<j)) gentris(cu[i], j, co, size);
					}
				}
			}
			else if(escaped&(1<<i))
			{
				ivec co(i, o, size);
				if(cu[i].children) findescaped(cu[i].children, co, size>>1, cu[i].escaped);
				else
				{
					int vismask = cu[i].merged;
					if(vismask) loopj(6) if(vismask&(1<<j)) gentris(cu[i], j, co, size);
				}
			}
		}
	}
};

decalrenderer decals[] =
{
	decalrenderer("<grey>packages/particles/scorch.png", DF_ROTATE, 500),
	decalrenderer("<grey>packages/particles/blood.png", DF_RND4|DF_ROTATE|DF_INVMOD),
	decalrenderer("<grey>packages/particles/bullet.png", DF_OVERBRIGHT)
};

void initdecals()
{
	loopi(sizeof(decals)/sizeof(decals[0])) decals[i].init(maxdecaltris);
}

void cleardecals()
{
	loopi(sizeof(decals)/sizeof(decals[0])) decals[i].cleardecals();
}

void cleanupdecals()
{
	loopi(sizeof(decals)/sizeof(decals[0])) decals[i].cleanup();
}

VARNP(decals, showdecals, 0, 1, 1);

void renderdecals(bool mainpass)
{
	bool rendered = false;
	loopi(sizeof(decals)/sizeof(decals[0]))
	{
		decalrenderer &d = decals[i];
		if(mainpass)
		{
			d.clearfadeddecals();
			d.fadeindecals();
			d.fadeoutdecals();
		}
		if(!showdecals || !d.hasdecals()) continue;
		if(!rendered)
		{
			rendered = true;
			decalrenderer::setuprenderstate();
		}
		d.render();
	}
	if(!rendered) return;
	decalrenderer::cleanuprenderstate();
}

VARP(maxdecaldistance, 1, 512, 10000);

void adddecal(int type, const vec &center, const vec &surface, float radius, const bvec &color, int info)
{
	if(!showdecals || type<0 || (size_t)type>=sizeof(decals)/sizeof(decals[0]) || center.dist(camera1->o) - radius > maxdecaldistance) return;
	decalrenderer &d = decals[type];
	d.adddecal(center, surface, radius, color, info);
}