详细介绍HTML53D衣服摇摆动画特效如何实现

<p style="width:500px;margin:10px auto">
	<canvas id="cv" width="480" height="300"></canvas>
	<p>"3D on 2D Canvas" demo</p>
	<p>move cursor to pan / click to swing</p>
</p>

window.P3D = {
	texture: null,
	g: null
};

P3D.clear = function(f, w, h) {
	var g = this.g;
	g.beginPath();
	g.fillStyle = f;
	g.fillRect(0, 0, w, h);

}

P3D.num_cmp = function(a,b){return a-b;}

P3D.drawTriangle = function(poss, uvs, shade_clr) {
	var w = this.texture.width;
	var h = this.texture.height;

	var g = this.g;

	var vAd = [ poss[1].x - poss[0].x , poss[1].y - poss[0].y ];
	var vBd = [ poss[2].x - poss[0].x , poss[2].y - poss[0].y ];

	var vA = [ uvs[1].u - uvs[0].u , uvs[1].v - uvs[0].v ];
	var vB = [ uvs[2].u - uvs[0].u , uvs[2].v - uvs[0].v ];

	vA[0] *= w;
	vA[1] *= h;

	vB[0] *= w;
	vB[1] *= h;

	var m = new M22();
	m._11 = vA[0];
	m._12 = vA[1];
	m._21 = vB[0];
	m._22 = vB[1];

	var im = m.getInvert();
	if (!im) return false;

	var a = im._11 * vAd[0] + im._12 * vBd[0];
	var b = im._21 * vAd[0] + im._22 * vBd[0];

	var c = im._11 * vAd[1] + im._12 * vBd[1];
	var d = im._21 * vAd[1] + im._22 * vBd[1];

	var wu = uvs[0].u * w;
	var hv = uvs[0].v * h;
	var du = wu * a + hv * b;
	var dv = wu * c + hv * d;

	g.save();

	g.beginPath();
	g.moveTo(poss[0].x, poss[0].y);
	g.lineTo(poss[1].x, poss[1].y);
	g.lineTo(poss[2].x, poss[2].y);
	g.clip();

	g.transform(a, c, b, d, poss[0].x - du, poss[0].y - dv);

	// bounds
	var bx = [wu, wu+vA[0], wu+vB[0]];
	var by = [hv, hv+vA[1], hv+vB[1]];

	bx.sort(P3D.num_cmp);
	by.sort(P3D.num_cmp);

	var bw = bx[2] - bx[0];
	var bh = by[2] - by[0];

	if ((bx[0]+bw) <= (w-1)) bw++;
	if ((by[0]+bh) <= (h-1)) bh++;
	if (bx[0] >= 1) {bx[0]--; bw++;}
	if (by[0] >= 1) {by[0]--; bh++;}

	g.drawImage(this.texture, bx[0], by[0], bw, bh, bx[0], by[0], bw, bh);

	if (shade_clr) {
	g.fillStyle = shade_clr;
	g.fillRect(bx[0], by[0], bw, bh);
	}

	g.restore();

	return true;
}

P3D.drawTestByIndexBuffer = function(pos_buf, ix_buf, culling) {
	var g = this.g;

	if ((ix_buf.length%3) != 0)
	throw "invalid index buffer length!";

	var len = ix_buf.length/3;

	var i, ibase, vbase;
	var poss = [{},{},{}];
	g.strokeWidth = 1;
	for (i = 0, ibase = 0;i < len;++i)
	{
	vbase = ix_buf[ibase++] << 2;
	poss[0].x = pos_buf[vbase++];
	poss[0].y = pos_buf[vbase ];

	vbase = ix_buf[ibase++] << 2;
	poss[1].x = pos_buf[vbase++];
	poss[1].y = pos_buf[vbase ];

	vbase = ix_buf[ibase++] << 2;
	poss[2].x = pos_buf[vbase++];
	poss[2].y = pos_buf[vbase ];

	// z component of cross product < 0 ?

	var Ax = poss[1].x - poss[0].x;
	var Ay = poss[1].y - poss[0].y;
	var Cx = poss[2].x - poss[1].x;
	var Cy = poss[2].y - poss[1].y;

	var cull = ( (((Ax * Cy) - (Ay * Cx))*culling) < 0);

	g.beginPath();
	g.strokeStyle = cull ? "#592" : "#0f0";
	g.moveTo(poss[0].x, poss[0].y);
	g.lineTo(poss[1].x, poss[1].y);
	g.lineTo(poss[2].x, poss[2].y);
	g.lineTo(poss[0].x, poss[0].y);
	g.stroke();
	}
}

P3D.drawByIndexBuffer = function(pos_buf, ix_buf, tx_buf, culling, z_clip) {
	var w, h;
	var color_polygon = !this.texture;
	if (this.texture) {
	w = this.texture.width;
	h = this.texture.height;
	}

	var g = this.g;
	var m = new M22();

	if (!culling) culling = 0;

	if ((ix_buf.length%3) != 0)
	throw "invalid index buffer length!";

	var i, ibase, vbase, tbase, poss = [{},{},{}];
	var len = ix_buf.length/3;
	var uv_0u, uv_0v, uv_1u, uv_1v, uv_2u, uv_2v;

	for (i = 0, ibase = 0;i < len;++i)
	{
	tbase = ix_buf[ibase++] << 1
	vbase = tbase << 1;
	poss[0].x = pos_buf[vbase++]; uv_0u = tx_buf[tbase++];
	poss[0].y = pos_buf[vbase++]; uv_0v = tx_buf[tbase];
	if (z_clip && (pos_buf[vbase] < 0 || pos_buf[vbase] > 1)) {ibase += 2; continue;}

	tbase = ix_buf[ibase++] << 1
	vbase = tbase << 1;
	poss[1].x = pos_buf[vbase++]; uv_1u = tx_buf[tbase++];
	poss[1].y = pos_buf[vbase++]; uv_1v = tx_buf[tbase];
	if (z_clip && (pos_buf[vbase] < 0 || pos_buf[vbase] > 1)) {++ibase; continue;}

	tbase = ix_buf[ibase++] << 1
	vbase = tbase << 1;
	poss[2].x = pos_buf[vbase++]; uv_2u = tx_buf[tbase++];
	poss[2].y = pos_buf[vbase++]; uv_2v = tx_buf[tbase];
	if (z_clip && (pos_buf[vbase] < 0 || pos_buf[vbase] > 1)) {continue;}

	var vAd = [ poss[1].x - poss[0].x , poss[1].y - poss[0].y ];
	var vBd = [ poss[2].x - poss[0].x , poss[2].y - poss[0].y ];

	var vCd = [ poss[2].x - poss[1].x , poss[2].y - poss[1].y ];

	// z component of cross product < 0 ?
	if( (((vAd[0] * vCd[1]) - (vAd[1] * vCd[0]))*culling) < 0)
	continue;

	if (color_polygon) {
	g.fillStyle = uv_0u;

	g.beginPath();
	g.moveTo(poss[0].x, poss[0].y);
	g.lineTo(poss[1].x, poss[1].y);
	g.lineTo(poss[2].x, poss[2].y);
	g.fill();
	continue;
	}

	var vA = [ uv_1u - uv_0u , uv_1v - uv_0v ];
	var vB = [ uv_2u - uv_0u , uv_2v - uv_0v ];

	vA[0] *= w;
	vA[1] *= h;

	vB[0] *= w;
	vB[1] *= h;

	m._11 = vA[0];
	m._12 = vA[1];
	m._21 = vB[0];
	m._22 = vB[1];

	var im = m.getInvert();
	if (!im) { continue;}

	var a = im._11 * vAd[0] + im._12 * vBd[0];
	var b = im._21 * vAd[0] + im._22 * vBd[0];

	var c = im._11 * vAd[1] + im._12 * vBd[1];
	var d = im._21 * vAd[1] + im._22 * vBd[1];

	var wu = uv_0u * w;
	var hv = uv_0v * h;
	var du = wu * a + hv * b;
	var dv = wu * c + hv * d;

	g.save();

	g.beginPath();
	g.moveTo(poss[0].x, poss[0].y);
	g.lineTo(poss[1].x, poss[1].y);
	g.lineTo(poss[2].x, poss[2].y);
	g.clip();
	g.transform(a, c, b, d, poss[0].x - du, poss[0].y - dv);

	// bounds
	var bx = [wu, wu+vA[0], wu+vB[0]];
	var by = [hv, hv+vA[1], hv+vB[1]];

	bx.sort(P3D.num_cmp);
	by.sort(P3D.num_cmp);

	var bw = bx[2] - bx[0];
	var bh = by[2] - by[0];

	if ((bx[0]+bw) <= (w-1)) bw++;
	if ((by[0]+bh) <= (h-1)) bh++;
	if (bx[0] >= 1) {bx[0]--; bw++;}
	if (by[0] >= 1) {by[0]--; bh++;}

	g.drawImage(this.texture, bx[0], by[0], bw, bh, bx[0], by[0], bw, bh);
/*
	if (shade_clr) {
	g.fillStyle = shade_clr;
	g.fillRect(bx[0], by[0], bw, bh);
	}
*/
	g.restore();

	}

}

function Vec3(_x, _y, _z)
{
	this.x = _x || 0;
	this.y = _y || 0;
	this.z = _z || 0;
}

Vec3.prototype = {
	zero: function() {
	this.x = this.y = this.z = 0;
	},

	sub: function(v) {
	this.x -= v.x;
	this.y -= v.y;
	this.z -= v.z;

	return this;
	},

	add: function(v) {
	this.x += v.x;
	this.y += v.y;
	this.z += v.z;

	return this;
	},

	copyFrom: function(v) {
	this.x = v.x;
	this.y = v.y;
	this.z = v.z;

	return this;
	},

	norm:function() {
	return Math.sqrt(this.x*this.x + this.y*this.y + this.z*this.z);
	},

	normalize: function() {
	var nrm = Math.sqrt(this.x*this.x + this.y*this.y + this.z*this.z);
	if (nrm != 0)
	{
	this.x /= nrm;
	this.y /= nrm;
	this.z /= nrm;
	}
	return this;
	},

	smul: function(k) {
	this.x *= k;
	this.y *= k;
	this.z *= k;

	return this;
	},

	dpWith: function(v)	{
	return this.x*v.x + this.y*v.y + this.z*v.z;
	},

	cp: function(v, w) {
	this.x = (w.y * v.z) - (w.z * v.y);
	this.y = (w.z * v.x) - (w.x * v.z);
	this.z = (w.x * v.y) - (w.y * v.x);

	return this;
	},

	toString: function() {
	return this.x + ", " + this.y + "," + this.z;
	}
}

function M44(cpy)
{
	if (cpy)
	this.copyFrom(cpy);
	else {
	this.ident();
	}
}

M44.prototype = {
	ident: function() {
	 this._12 = this._13 = this._14 = 0;
	this._21 = this._23 = this._24 = 0;
	this._31 = this._32 = this._34 = 0;
	this._41 = this._42 = this._43 = 0;

	this._11 = this._22 = this._33 = this._44 = 1;

	return this;
	},

	copyFrom: function(m) {
	this._11 = m._11;
	this._12 = m._12;
	this._13 = m._13;
	this._14 = m._14;

	this._21 = m._21;
	this._22 = m._22;
	this._23 = m._23;
	this._24 = m._24;

	this._31 = m._31;
	this._32 = m._32;
	this._33 = m._33;
	this._34 = m._34;

	this._41 = m._41;
	this._42 = m._42;
	this._43 = m._43;
	this._44 = m._44;

	return this;
	},

	transVec3: function(out, x, y, z) {
	out[0] = x * this._11 + y * this._21 + z * this._31 + this._41;
	out[1] = x * this._12 + y * this._22 + z * this._32 + this._42;
	out[2] = x * this._13 + y * this._23 + z * this._33 + this._43;
	out[3] = x * this._14 + y * this._24 + z * this._34 + this._44;
	},

	transVec3Rot: function(out, x, y, z) {
	out[0] = x * this._11 + y * this._21 + z * this._31;
	out[1] = x * this._12 + y * this._22 + z * this._32;
	out[2] = x * this._13 + y * this._23 + z * this._33;
	},

	perspectiveLH: function(vw, vh, z_near, z_far) {
	this._11 = 2.0*z_near/vw;
	this._12 = 0;
	this._13 = 0;
	this._14 = 0;

	this._21 = 0;
	this._22 = 2*z_near/vh;
	this._23 = 0;
	this._24 = 0;

	this._31 = 0;
	this._32 = 0;
	this._33 = z_far/(z_far-z_near);
	this._34 = 1;

	this._41 = 0;
	this._42 = 0;
	this._43 = z_near*z_far/(z_near-z_far);
	this._44 = 0;

	return this;
	},

	lookAtLH: function(aUp, aFrom, aAt) {
	var aX = new Vec3();
	var aY = new Vec3();

	var aZ = new Vec3(aAt.x, aAt.y, aAt.z);
	aZ.sub(aFrom).normalize();

	aX.cp(aUp, aZ).normalize();
	aY.cp(aZ, aX);

	this._11 = aX.x; this._12 = aY.x; this._13 = aZ.x; this._14 = 0;
	this._21 = aX.y; this._22 = aY.y; this._23 = aZ.y; this._24 = 0;
	this._31 = aX.z; this._32 = aY.z; this._33 = aZ.z; this._34 = 0;

	this._41 = -aFrom.dpWith(aX);
	this._42 = -aFrom.dpWith(aY);
	this._43 = -aFrom.dpWith(aZ);
	this._44 = 1;

	 return this;
	},

	mul: function(A, B) {
	this._11 = A._11*B._11 + A._12*B._21 + A._13*B._31 + A._14*B._41;
	this._12 = A._11*B._12 + A._12*B._22 + A._13*B._32 + A._14*B._42;
	this._13 = A._11*B._13 + A._12*B._23 + A._13*B._33 + A._14*B._43;
	this._14 = A._11*B._14 + A._12*B._24 + A._13*B._34 + A._14*B._44;

	this._21 = A._21*B._11 + A._22*B._21 + A._23*B._31 + A._24*B._41;
	this._22 = A._21*B._12 + A._22*B._22 + A._23*B._32 + A._24*B._42;
	this._23 = A._21*B._13 + A._22*B._23 + A._23*B._33 + A._24*B._43;
	this._24 = A._21*B._14 + A._22*B._24 + A._23*B._34 + A._24*B._44;

	this._31 = A._31*B._11 + A._32*B._21 + A._33*B._31 + A._34*B._41;
	this._32 = A._31*B._12 + A._32*B._22 + A._33*B._32 + A._34*B._42;
	this._33 = A._31*B._13 + A._32*B._23 + A._33*B._33 + A._34*B._43;
	this._34 = A._31*B._14 + A._32*B._24 + A._33*B._34 + A._34*B._44;

	this._41 = A._41*B._11 + A._42*B._21 + A._43*B._31 + A._44*B._41;
	this._42 = A._41*B._12 + A._42*B._22 + A._43*B._32 + A._44*B._42;
	this._43 = A._41*B._13 + A._42*B._23 + A._43*B._33 + A._44*B._43;
	this._44 = A._41*B._14 + A._42*B._24 + A._43*B._34 + A._44*B._44;

	return this;
	},

	translate: function(x, y, z) {
	this._11 = 1; this._12 = 0; this._13 = 0; this._14 = 0;
	this._21 = 0; this._22 = 1; this._23 = 0; this._24 = 0;
	this._31 = 0; this._32 = 0; this._33 = 1; this._34 = 0;

	this._41 = x; this._42 = y; this._43 = z; this._44 = 1;
	return this;
	},

	transpose33: function() {
	var t;

	t = this._12;
	this._12 = this._21;
	this._21 = t;

	t = this._13;
	this._13 = this._31;
	this._31 = t;

	t = this._23;
	this._23 = this._32;
	this._32 = t;

	return this;
	},

	// OpenGL style rotation
	glRotate: function(angle, x, y, z) {
	var s = Math.sin( angle );
	var c = Math.cos( angle );

	var xx = x * x;
	var yy = y * y;
	var zz = z * z;
	var xy = x * y;
	var yz = y * z;
	var zx = z * x;
	var xs = x * s;
	var ys = y * s;
	var zs = z * s;
	var one_c = 1.0 - c;
/*
	this._11 = (one_c * xx) + c;
	this._21 = (one_c * xy) - zs;
	this._31 = (one_c * zx) + ys;
	this._41 = 0;

	this._12 = (one_c * xy) + zs;
	this._22 = (one_c * yy) + c;
	this._32 = (one_c * yz) - xs;
	this._42 = 0;

	this._13 = (one_c * zx) - ys;
	this._23 = (one_c * yz) + xs;
	this._33 = (one_c * zz) + c;
	this._43 = 0;

	this._14 = 0;
	this._24 = 0;
	this._34 = 0;
	this._44 = 1;
*/

	this._11 = (one_c * xx) + c;
	this._12 = (one_c * xy) - zs;
	this._13 = (one_c * zx) + ys;
	this._14 = 0;

	this._21 = (one_c * xy) + zs;
	this._22 = (one_c * yy) + c;
	this._23 = (one_c * yz) - xs;
	this._24 = 0;

	this._31 = (one_c * zx) - ys;
	this._32 = (one_c * yz) + xs;
	this._33 = (one_c * zz) + c;
	this._34 = 0;

	this._41 = 0;
	this._42 = 0;
	this._43 = 0;
	this._44 = 1;

	return this;
	}

}

// matrix 2x2
function M22()
{
	this._11 = 1;
	this._12 = 0;
	this._21 = 0;
	this._22 = 1;
}

M22.prototype.getInvert = function()
{
	var out = new M22();
	var det = this._11 * this._22 - this._12 * this._21;
	if (det > -0.0001 && det < 0.0001)
	return null;

	out._11 = this._22 / det;
	out._22 = this._11 / det;

	out._12 = -this._12 / det;
	out._21 = -this._21 / det;

	return out;
}

function ClothApp()
{
	this.canvas = document.getElementById("cv");

	P3D.g = this.canvas.getContext("2d");

	var tex = new Image();
	this.texture1 = tex;
	tex.onload = function(){ _this.start(); };
	tex.src = "20090226032826.gif";

	tex = new Image();
	this.texture2 = tex;
	tex.onload = function(){ _this.start(); };
	tex.src = "20090226032825.png";

	this.mLoadCount = 2;
	this.mTickCount = 0;

	this.G = 0.53;
	this.G1 = 0.45;
	this.mProjMat = null;
	this.mViewMat = null;
	this.mViewFrom = new Vec3();
	this.mViewFrom.y = -150;
	this.mViewFrom.z = 1000;
	this.mViewFromA = (new Vec3()).copyFrom(this.mViewFrom);

	this.mViewAngle = 0;

	this.mNLen = 0;
	this.mNodes = [];
	this.mRenderTris = null;

	this.mLTNode = null;
	this.mRTNode = null;

	this.mLTNodeV = new Vec3();
	this.mRTNodeV = new Vec3();

	this.mWForce = new Vec3();
	this.frate = 15;

	var _this = this;
}

ClothApp.zsortCmp = function(t1, t2) {
	return t2.sortKey - t1.sortKey;
}

ClothApp.prototype = {
	start: function() {
	if (--this.mLoadCount != 0) return;

	this.vUP = new Vec3(0, 1, 0);
	this.vAT = new Vec3(0, 80, 0);

	this.mViewport = {};
	this.mViewport.w = 480;
	this.mViewport.h = 300;
	this.mViewport.ow = 240;
	this.mViewport.oh = 150;
	this.setupTransforms();

	this.generateCloth(180);
	this.generateRenderTriangles();

	var _this = this;
	this.canvas.addEventListener("mousemove", function(e){_this.onMouseMove(e);}, false);
	this.canvas.addEventListener("mousedown", function(e){_this.onClick(e);}, false);

	window.setTimeout(function(){_this.onInterval();}, this.frate);
	},

	onInterval: function() {
	this.mTickCount++;

	// this.mLTNodeV.z = Math.cos(this.mTickCount*0.1) * 2;

	this.tick();
	this.updatePosition();
	this.draw();

	var _this = this;
	window.setTimeout(function(){_this.onInterval();}, this.frate);
	},

	onMouseMove: function(e) {
	if (e.clientX || e.clientX == 0)
	this.mViewAngle = (e.clientX - 240) * 0.004;

	if (e.clientY || e.clientY == 0)
	this.mViewFromA.y = 90 - (e.clientY - 0) * 0.8;
	},

	onClick: function(e) {
	if (e.clientX || e.clientX == 0)
	{
	this.mWForce.z = -4;
	this.mWForce.x = (e.clientX - 240) * -0.03;
	}
	},

	tick: function() {
	this.updateViewTrans(this.mViewAngle);

	var nlen = this.mNodes.length;
	var i, nd;
	for(i = 0;i < nlen;i++)
	{
	nd = this.mNodes[i];
	nd.F.x = 0;
	nd.F.z = 0;
	if (nd.flags & 4)
	nd.F.y = -this.G1;
	else
	nd.F.y = -this.G;

	nd.F.add(this.mWForce);
	}

	this.mWForce.zero();
	this.applyTension();

	for(i = 0;i < nlen;i++)
	{
	nd = this.mNodes[i];

	if ((nd.flags&1) != 0) {
	nd.F.sub(nd.F);
	}

	nd.velo.add(nd.F);
	}

	this.mLTNode.velo.copyFrom(this.mLTNodeV);
	this.mRTNode.velo.copyFrom(this.mRTNodeV);
	},

	updatePosition: function() {
	var nlen = this.mNodes.length;
	var i, nd;
	for(i = 0;i < nlen;i++)
	{
	nd = this.mNodes[i];

	if ((nd.flags&1) != 0) {
	nd.cv.x = 0;
	nd.cv.y = 0;
	nd.cv.z = 0;
	}

	nd.pos.add(nd.velo);
	nd.velo.sub(nd.cv);
	nd.cv.x = 0;
	nd.cv.y = 0;
	nd.cv.z = 0;

	nd.velo.smul(0.95);
	}
	},

	draw: function() {
	P3D.clear("#000", this.mViewport.w, this.mViewport.h);
	this.transformPolygons();

	this.mRenderTris.sort(ClothApp.zsortCmp);
	var len = this.mRenderTris.length;
	var t, sh;
	for (var i = 0;i < len;i++) {
	t = this.mRenderTris[i];

	if (P3D.texture != t.texture)
	P3D.texture = t.texture;

	sh = undefined;
	if (t.lighting && t.shade > 0.01)
	sh = "rgba(0,0,0,"+t.shade+")";
	P3D.drawTriangle(t.tposs, t.uvs, sh);
	}
	},

	applyTension: function() {
	var i, k, nd;
	var v = new Vec3();
	var nlen = this.mNodes.length;
	var naturalLen = this.mNLen;

	for (k = 0;k < nlen;k++)
	{
	nd = this.mNodes[k];
	var F = nd.F;

	for (i = 0;i < 4;i++)
	{
	var nbr = nd.links[i];
	if (!nbr) continue;

	var len = v.copyFrom(nbr.pos).sub(nd.pos).norm();
	var dlen = len - naturalLen;
	if (dlen > 0) {
	v.smul(dlen * 0.5 / len);

	F.x += v.x;
	F.y += v.y;
	F.z += v.z;
	nd.cv.add(v.smul(0.8));
	}
	}
	}	
	},

	setupTransforms: function() {
	this.mProjMat = new M44();
	this.mProjMat.perspectiveLH(24, 15, 10, 9000);

	this.mViewMat = new M44();
	this.updateViewTrans(0);
	},

	updateViewTrans: function(ry) {
	this.mViewFromA.z = Math.cos(ry) * 380;
	this.mViewFromA.x = Math.sin(ry) * 380;

	this.mViewFrom.smul(0.7);
	this.mViewFrom.x += this.mViewFromA.x * 0.3;
	this.mViewFrom.y += this.mViewFromA.y * 0.3;
	this.mViewFrom.z += this.mViewFromA.z * 0.3;

	this.mViewMat.lookAtLH(this.vUP, this.mViewFrom, this.vAT);
	},

	generateCloth: function(base_y) {
	var cols = 9;
	var rows = 8;

	var step = 22;
	this.mNLen = step*0.9;
	var w = (cols-1) * step;

	var i, k;
	for (k = 0;k < rows;k++)
	{
	for (i = 0;i < cols;i++)
	{
	var nd = new ClothNode();
	nd.pos.x = -(w/2) + i*step;
	nd.pos.y = base_y -k*step/2;
	nd.pos.z = k*16;

	nd.uv.u = i / (cols-1);
	nd.uv.v = k / (rows-1);

	if (i > 0) {
	var prv_nd = this.mNodes[this.mNodes.length-1];
	prv_nd.links[1] = nd;
	nd.links[0] = prv_nd;
	}

	if (k > 0) {
	var up_nd = this.mNodes[this.mNodes.length-cols];
	up_nd.links[4] = nd;
	nd.links[3] = up_nd;
	}

	if (i != 0 && i != 4 && i != (cols-1))
	nd.flags |= 4;

	this.mNodes.push(nd);
	}
	}

	// fix left-top and right-top
	this.mNodes[0 ].flags |= 1;
	this.mNodes[4 ].flags |= 1;
	this.mNodes[cols-1].flags |= 1;

	this.mLTNode = this.mNodes[0 ];
	this.mRTNode = this.mNodes[cols-1];
	},

	generateRenderTriangles: function()
	{
	if (!this.mRenderTris) this.mRenderTris = [];

	var i;
	var nd;
	var nlen = this.mNodes.length;

	for(i = 0;i < nlen;i++)
	{
	nd = this.mNodes[i];
	if (nd.links[1] && nd.links[1].links[4]) {
	var t = new RenderTriangle();
	t.texture = this.texture1;

	t.poss[0] = nd.pos;
	t.poss[1] = nd.links[1].pos;
	t.poss[2] = nd.links[1].links[4].pos;

	t.uvs[0] = nd.uv;
	t.uvs[1] = nd.links[1].uv;
	t.uvs[2] = nd.links[1].links[4].uv;

	this.mRenderTris.push(t);

	t = new RenderTriangle();
	t.texture = this.texture1;

	t.poss[0] = nd.pos;
	t.poss[1] = nd.links[1].links[4].pos;
	t.poss[2] = nd.links[4].pos;

	t.uvs[0] = nd.uv;
	t.uvs[1] = nd.links[1].links[4].uv;
	t.uvs[2] = nd.links[4].uv;

	this.mRenderTris.push(t);
	}
	}

	this.addBGTriangles(this.mNodes[0].pos.y);
	},

	addBGTriangles: function(by) {
	var cols = 4;
	var t, x, y, sz = 110;
	var ox = -(cols*sz)/2;
	var oz = -(cols*sz)/2;

	for (y = 0;y < cols;y++) {
	for (x = 0;x < cols;x++) {
	var bv = ((x+y)&1) * 0.5;
	t = new RenderTriangle();
	t.texture = this.texture2;

	t.poss[0] = new Vec3(ox + x*sz , by, oz + y*sz );
	t.poss[1] = new Vec3(ox + x*sz + sz, by, oz + y*sz );
	t.poss[2] = new Vec3(ox + x*sz , by, oz + y*sz + sz);

	t.uvs[0] = {u:0 , v:bv };
	t.uvs[1] = {u:0.5, v:bv };
	t.uvs[2] = {u:0 , v:bv+0.5};

	if ((x==1 || x==2) && (y==1 || y==2))
	this.modifyRoofUV(t, x == 2, bv);

	t.lighting = false;
	t.zBias = 0.5;
	this.mRenderTris.push(t);

	t = new RenderTriangle();
	t.texture = this.texture2;

	t.poss[0] = new Vec3(ox + x*sz , by, oz + y*sz + sz);
	t.poss[1] = new Vec3(ox + x*sz + sz, by, oz + y*sz );
	t.poss[2] = new Vec3(ox + x*sz + sz, by, oz + y*sz + sz);

	t.uvs[0] = {u:0 , v:bv+0.5};
	t.uvs[1] = {u:0.5, v:bv };
	t.uvs[2] = {u:0.5, v:bv+0.5};

	if ((x==1 || x==2) && (y==1 || y==2))
	this.modifyRoofUV(t, x == 2, bv);

	t.lighting = false;
	t.zBias = 0.5;
	this.mRenderTris.push(t);

	}
	}
	},

	modifyRoofUV: function(t, rv, bv) {
	if (rv) {
	t.uvs[0].u = 0.5 - t.uvs[0].u;
	t.uvs[1].u = 0.5 - t.uvs[1].u;
	t.uvs[2].u = 0.5 - t.uvs[2].u;
	}

	t.uvs[0].u += 0.5;
	t.uvs[1].u += 0.5;
	t.uvs[2].u += 0.5;

	if (rv) {
	t.uvs[0].v = 0.5 - t.uvs[0].v + bv + bv;
	t.uvs[1].v = 0.5 - t.uvs[1].v + bv + bv;
	t.uvs[2].v = 0.5 - t.uvs[2].v + bv + bv;
	}

	},

	transformPolygons: function() {
	var trans = new M44();
	trans.mul(this.mViewMat, this.mProjMat);

	var hw = this.mViewport.ow;
	var hh = this.mViewport.oh;

	var len = this.mRenderTris.length;
	var t;
	var spos = [0, 0, 0, 0];
	for (var i = 0;i < len;i++) {
	t = this.mRenderTris[i];
	for (var k = 0;k < 3;k++) {
	trans.transVec3(spos, t.poss[k].x, t.poss[k].y, t.poss[k].z);

	var W = spos[3];
	spos[0] /= W;
	spos[1] /= W;
	spos[2] /= W;

	spos[0] *= this.mViewport.w;
	spos[1] *= -this.mViewport.h;
	spos[0] += hw;
	spos[1] += hh;

	t.tposs[k].x = spos[0];
	t.tposs[k].y = spos[1];
	t.tposs[k].z = spos[2];
	}

	var v1 = (new Vec3()).copyFrom(t.poss[1]).sub(t.poss[0]).normalize();
	var v2 = (new Vec3()).copyFrom(t.poss[2]).sub(t.poss[1]).normalize();
	var N = (new Vec3()).cp(v1, v2);

	trans.transVec3Rot(spos, N.x, N.y, N.z);

	if (t.lighting) {
	if (spos[2] > 0)
	t.shade = 0.8
	else {
	t.shade = 0.1 - N.y * 0.6;
	if (t.shade < 0) t.shade = 0;
	}
	}

	t.sortKey = Math.floor( (t.tposs[0].z + t.tposs[1].z + t.tposs[2].z + t.zBias) *1000 );
	}
	}
}

function ClothNode()
{
	this.flags = 0;
	this.pos = new Vec3();
	this.velo = new Vec3();
	this.cv = new Vec3();
	this.F = new Vec3();
	this.links = [null, null, null, null];
	this.uv = {u:0, v:0};
}

function RenderTriangle()
{
	this.texture = null;
	this.poss = new Array(3);
	this.tposs = [new Vec3(), new Vec3(), new Vec3()];
	this.uvs = [{u:0, v:0}, {u:0, v:0}, {u:0, v:0}];
	this.shade = 0;
	this.lighting = true;
	this.zBias = 0;

	this.sortKey = 0;
}