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// Helper function for generating a RDGE primitive
var ShapePrimitive = {};

ShapePrimitive.create = function(coords,  normals,  uvs,  indices, primType, vertexCount) {
    var renderer = RDGE.globals.engine.getContext().renderer;

    // to setup a primitive you must define it
    // create a new primitive definition here to then fill out
    var prim = new RDGE.rdgePrimitiveDefinition();

    // the vertex definition declares how the data will be delivered to the shader
    // the position of an element in array determines which attribute in a shader the
    // data is bound to
    prim.vertexDefinition = {
        // this shows two ways to map this data to an attribute
        "vert":{'type':renderer.VS_ELEMENT_POS, 'bufferIndex':0, 'bufferUsage': renderer.BUFFER_STATIC},
        "a_pos":{'type':renderer.VS_ELEMENT_POS, 'bufferIndex':0, 'bufferUsage': renderer.BUFFER_STATIC},

        "normal":{'type':renderer.VS_ELEMENT_FLOAT3, 'bufferIndex':1, 'bufferUsage': renderer.BUFFER_STATIC},
        "a_nrm":{'type':renderer.VS_ELEMENT_FLOAT3, 'bufferIndex':1, 'bufferUsage': renderer.BUFFER_STATIC},
        "a_normal":{'type':renderer.VS_ELEMENT_FLOAT3, 'bufferIndex':1, 'bufferUsage': renderer.BUFFER_STATIC},

        "texcoord":{'type':renderer.VS_ELEMENT_FLOAT2, 'bufferIndex':2, 'bufferUsage': renderer.BUFFER_STATIC},
        "a_texcoord":{'type':renderer.VS_ELEMENT_FLOAT2, 'bufferIndex':2, 'bufferUsage': renderer.BUFFER_STATIC}
    };

    // the actual data that correlates to the vertex definition
    prim.bufferStreams = [ coords, normals, uvs ];

    // what type of buffers the data resides in, static is the most common case
    prim.streamUsage = [ renderer.BUFFER_STATIC, renderer.BUFFER_STATIC, renderer.BUFFER_STATIC ];

    // this tells the renderer to draw the primitive as a list of triangles
    prim.type = primType;

    prim.indexUsage = renderer.BUFFER_STREAM;
    prim.indexBuffer = indices;

    // finally the primitive is created, buffers are generated and the system determines
    // the data it needs to draw this primitive according to the previous definition
    renderer.createPrimitive(prim, vertexCount);

    return prim;
};

ShapePrimitive.getMeshBounds = function( verts,  nVerts )
{
    if (!verts || (nVerts <= 0))  return null;

    var bounds = [verts[0], verts[1], verts[2],  verts[0], verts[1], verts[2]];
    var index = 3;
    for (var i=1;  i<nVerts;  i++)
    {
        var x = verts[index],  y = verts[index+1],  z = verts[index+2];
        index += 3;

        if      (x < bounds[0])  bounds[0] = x;
        else if (x > bounds[3])  bounds[3] = x;
        if      (y < bounds[1])  bounds[1] = y;
        else if (y > bounds[4])  bounds[4] = y;
        if      (z < bounds[2])  bounds[2] = z;
        else if (z > bounds[5])  bounds[5] = z;
    }

    return bounds;
};

ShapePrimitive.getBounds = function( prim )
{
    var verts = prim.bufferStreams[0];
    var nVerts = verts.length;
    var xMin = verts[0],  xMax = verts[0],
        yMin = verts[1],  yMax = verts[1],
        zMin = verts[2],  zMax = verts[2];

    for (var index=3;  index<verts.length;  )
    {
        if (verts[index] < xMin)  xMin = verts[index];
        else if (verts[index] > xMax)  xMax = verts[index];

        index++;
        if (verts[index] < yMin)  yMin = verts[index];
        else if (verts[index] > yMax)  yMax = verts[index];

        index++;
        if (verts[index] < zMin)  zMin = verts[index];
        else if (verts[index] > zMax)  zMax = verts[index];

        index++;
    }

    return [xMin, yMin, zMin,  xMax, yMax, zMax];
};

ShapePrimitive.refineMesh = function( verts, norms, uvs, indices, nVertices,  paramRange,  tolerance )
{
    var oldVrtCount = nVertices;

    // get the param range
    var pUMin = paramRange[0],  pVMin = paramRange[1],
        pUMax = paramRange[2],  pVMax = paramRange[3];
    var iTriangle = 0;
    var nTriangles = indices.length/3;
    var index = 0;
    while (iTriangle < nTriangles)
    {
        // get the indices of the 3 vertices
        var i0 = indices[index],
            i1 = indices[index+1],
            i2 = indices[index+2];

        // get the uv values
        //var vrtIndex = 3*iTriangle;
        var iuv0 = 2 * i0,
            iuv1 = 2 * i1,
            iuv2 = 2 * i2;
        var u0 = uvs[iuv0],  v0 = uvs[iuv0+1],
            u1 = uvs[iuv1],  v1 = uvs[iuv1+1],
            u2 = uvs[iuv2],  v2 = uvs[iuv2+1];

        // find the u and v range
        var uMin = u0,  vMin = v0;
        if (u1 < uMin)  uMin = u1;  if (v1 < vMin)  vMin = v1;
        if (u2 < uMin)  uMin = u2;  if (v2 < vMin)  vMin = v2;
        var uMax = u0,  vMax = v0;
        if (u1 > uMax)  uMax = u1;  if (v1 > vMax)  vMax = v1;
        if (u2 > uMax)  uMax = u2;  if (v2 > vMax)  vMax = v2;

        // if the parameter range of the triangle is outside the
        // desired parameter range, advance to the next polygon and continue
        if ((uMin > pUMax) || (uMax < pUMin) || (vMin > pVMax) || (vMax < pVMin))
        {
            // go to the next triangle
            iTriangle++;
            index += 3;
        }
        else
        {
            // check thesize of the triangle in uv space.  If small enough, advance
            // to the next triangle.  If not small enough, split the triangle into 3;
			var du = Math.abs(uMax) - uMin,  dv = Math.abs(vMax - vMin);
            if ((du < tolerance) && (dv < tolerance))
            {
                iTriangle++;
                index += 3;
            }
            else    // split the triangle into 4 parts
            {
                //calculate the position of the new vertex
                var iPt0 = 3 * i0,
                    iPt1 = 3 * i1,
                    iPt2 = 3 * i2;
                var x0 = verts[iPt0],  y0 = verts[iPt0+1],  z0 = verts[iPt0+2],
                    x1 = verts[iPt1],  y1 = verts[iPt1+1],  z1 = verts[iPt1+2],
                    x2 = verts[iPt2],  y2 = verts[iPt2+1],  z2 = verts[iPt2+2];

                // calculate the midpoints of the edges
                var xA = (x0 + x1)/2.0,  yA = (y0 + y1)/2.0,  zA = (z0 + z1)/2.0,
                    xB = (x1 + x2)/2.0,  yB = (y1 + y2)/2.0,  zB = (z1 + z2)/2.0,
                    xC = (x2 + x0)/2.0,  yC = (y2 + y0)/2.0,  zC = (z2 + z0)/2.0;

                // calculate the uv values of the new coordinates
                var uA = (u0 + u1)/2.0,  vA = (v0 + v1)/2.0,
                    uB = (u1 + u2)/2.0,  vB = (v1 + v2)/2.0,
                    uC = (u2 + u0)/2.0,  vC = (v2 + v0)/2.0;

                // calculate the normals for the new points
                var nx0 = norms[iPt0],  ny0 = norms[iPt0+1],  nz0 = norms[iPt0+2],
                    nx1 = norms[iPt1],  ny1 = norms[iPt1+1],  nz1 = norms[iPt1+2],
                    nx2 = norms[iPt2],  ny2 = norms[iPt2+1],  nz2 = norms[iPt2+2];
                var nxA = (nx0 + nx1),  nyA = (ny0 + ny1),  nzA = (nz0 + nz1);  var nrmA = VecUtils.vecNormalize(3, [nxA, nyA, nzA], 1.0 ),
                    nxB = (nx1 + nx2),  nyB = (ny1 + ny2),  nzB = (nz1 + nz2);  var nrmB = VecUtils.vecNormalize(3, [nxB, nyB, nzB], 1.0 ),
                    nxC = (nx2 + nx0),  nyC = (ny2 + ny0),  nzC = (nz2 + nz0);  var nrmC = VecUtils.vecNormalize(3, [nxC, nyC, nzC], 1.0 );

                // push everything
                verts.push(xA);  verts.push(yA);  verts.push(zA);
                verts.push(xB);  verts.push(yB);  verts.push(zB);
                verts.push(xC);  verts.push(yC);  verts.push(zC);
                uvs.push(uA),  uvs.push(vA);
                uvs.push(uB),  uvs.push(vB);
                uvs.push(uC),  uvs.push(vC);
                norms.push(nrmA[0]);  norms.push(nrmA[1]);  norms.push(nrmA[2]);
                norms.push(nrmB[0]);  norms.push(nrmB[1]);  norms.push(nrmB[2]);
                norms.push(nrmC[0]);  norms.push(nrmC[1]);  norms.push(nrmC[2]);

                // split the current triangle into 4
                indices[index+1] = nVertices;  indices[index+2] = nVertices+2;
                indices.push(nVertices);    indices.push(i1);           indices.push(nVertices+1);  nTriangles++;
                indices.push(nVertices+1);  indices.push(i2);           indices.push(nVertices+2);  nTriangles++;
                indices.push(nVertices);    indices.push(nVertices+1);  indices.push(nVertices+2);  nTriangles++;
                nVertices += 3;

                // by not advancing 'index', we examine the first of the 3 triangles generated above
            }
        }
    }

    console.log( "refine mesh vertex count " + oldVrtCount  + " => " + nVertices );
    return nVertices;
};

ShapePrimitive.convertTriangleStripToTriangles = function( indices )
{
	if (!indices || (indices.length < 3))  return;

	var indOut = [];
	var nInd = indices.length;
	for (var i=2;  i<nInd;  i++)
	{
		indOut.push( indices[i-2] );
		indOut.push( indices[i-1] );
		indOut.push( indices[i] );
	}

	return indOut;
};

ShapePrimitive.subdivideOversizedMesh = function( vertices, normals, uvs, indices )
{
	var rtnArray;
	var nVrtBytes = vertices.length*4,
		nIndBytes = indices.length*4;

	// only subdivide the input mesh if it exceeds limits
	if ((nVrtBytes >= 65000) || (nIndBytes >= 65000))
	{
		var nVerts = vertices.length / 3;
		var nVerts0 = 0,  nVerts1 = 0;
		var iSplitVrt = nVerts/2;	// any triangle referencing vertex iSplitVrt or greater goes to the second half
		var nTriangles = indices.length/3;
		var v0 = [],  v1 = [],  n0 = [],  n1 = [],  uv0 = [],  uv1 = [],  i0 = [],  i1 = [];
		var map0 = [],  map1 = [];
		var index = 0;
		for (var iTri=0;  iTri<nTriangles;  iTri++)
		{
			// determine which side to move the triangle into
			var vDst,  nDst, uvDst, iDst, mapDst, nOut;
			var iVrts = [ indices[index], indices[index+1], indices[index+2] ];
			if ( (iVrts[0] >= iSplitVrt) || (iVrts[1] >= iSplitVrt) || (iVrts[2] >= iSplitVrt) )
			{
				vDst  = v0;  nDst = n0;  uvDst = uv0;  iDst = i0;  mapDst = map0;  nOut = v0.length / 3;
			}
			else
			{
				vDst  = v1;  nDst = n1;  uvDst = uv1;  iDst = i1;  mapDst = map1;  nOut = v1.length / 3;
			}

			for (var i=0;  i<3;  i++)
			{
				var iVrt = iVrts[i];

				// if this is the first time that the vertex has been encountered, copy it over to the output
				var iOut = mapDst[iVrt];
				if (!iOut)
				{
					mapDst[iVrt] = nOut;
					vDst.push( vertices[3*iVrt] );  vDst.push(  vertices[3*iVrt + 1] );  vDst.push(  vertices[3*iVrt + 2] );
					nDst.push( normals[3*iVrt] );   nDst.push(  normals[3*iVrt + 1] );   nDst.push(  normals[3*iVrt + 2] );
					uvDst.push( uvs[2*iVrt] );      uvDst.push(  uvs[2*iVrt + 1] );
					iDst.push( nOut );
					nOut++;
				}
				else
					iDst.push( iOut );
			}

			index += 3;
		}

		// create objects out of the 2 halves
		var obj1 =
					{
						vertices:	v0,
						normals:	n0,
						uvs:		uv0,
						indices:	i0
					},
			obj2 =
			{
				vertices:	v1,
				normals:	n1,
				uvs:		uv1,
				indices:	i1
			};

		console.log( "mesh split into 2 parts: " + obj1.vertices.length/3 + ", " + obj2.vertices.length/3 );

		// recurse on the 2 halves in case they need subdivision
		var arr1 = ShapePrimitive.subdivideOversizedMesh( obj1.vertices, obj1.normals, obj1.uvs, obj1.indices );
		var arr2 = ShapePrimitive.subdivideOversizedMesh( obj2.vertices, obj2.normals, obj2.uvs, obj2.indices );
		rtnArray = arr1.concat( arr2 );
	}
	else
	{
		rtnArray =
		[
			{
				vertices:	vertices,
				normals:	normals,
				uvs:		uvs,
				indices:	indices
			}
		];
	}

	return rtnArray;
};


////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

ShapePrimitive.convertTrianglesToLines = function( verts, norms, uvs, indices,   vertsOut, normsOut,  uvsOut, indicesOut )
{
	var iTriangle = 0;
	var nTriangles = indices.length/3;
	var index = 0;
	var nVertices = 0;
	while (iTriangle < nTriangles)
	{
		// get the indices of the 3 vertices
		var i0 = indices[index],
			i1 = indices[index+1],
			i2 = indices[index+2];

		// get the uv values
		//var vrtIndex = 3*iTriangle;
		var iuv0 = 2 * i0,
			iuv1 = 2 * i1,
			iuv2 = 2 * i2;
		var u0 = uvs[iuv0],  v0 = uvs[iuv0+1],
			u1 = uvs[iuv1],  v1 = uvs[iuv1+1],
			u2 = uvs[iuv2],  v2 = uvs[iuv2+1];

		//calculate the position of the new vertex
		var iPt0 = 3 * i0,
			iPt1 = 3 * i1,
			iPt2 = 3 * i2;
		var x0 = verts[iPt0],  y0 = verts[iPt0+1],  z0 = verts[iPt0+2],
			x1 = verts[iPt1],  y1 = verts[iPt1+1],  z1 = verts[iPt1+2],
			x2 = verts[iPt2],  y2 = verts[iPt2+1],  z2 = verts[iPt2+2];

		// calculate the normals for the new points
		var nx0 = norms[iPt0],  ny0 = norms[iPt0+1],  nz0 = norms[iPt0+2],
			nx1 = norms[iPt1],  ny1 = norms[iPt1+1],  nz1 = norms[iPt1+2],
			nx2 = norms[iPt2],  ny2 = norms[iPt2+1],  nz2 = norms[iPt2+2];

		// push everything
		vertsOut.push( x0 );		vertsOut.push( y0 );		vertsOut.push( z0 );
		vertsOut.push( x1 );		vertsOut.push( y1 );		vertsOut.push( z1 );
		vertsOut.push( x1 );		vertsOut.push( y1 );		vertsOut.push( z1 );
		vertsOut.push( x2 );		vertsOut.push( y2 );		vertsOut.push( z2 );
		vertsOut.push( x2 );		vertsOut.push( y2 );		vertsOut.push( z2 );
		vertsOut.push( x0 );		vertsOut.push( y0 );		vertsOut.push( z0 );
		indicesOut.push( index );		indicesOut.push( index + 1 );
		indicesOut.push( index + 1 );	indicesOut.push( index + 2 );
		indicesOut.push( index + 2 );	indicesOut.push( index );

		normsOut.push( nx0 );		normsOut.push( ny0 );		normsOut.push( nz0 );
		normsOut.push( nx1 );		normsOut.push( ny1 );		normsOut.push( nz1 );
		normsOut.push( nx1 );		normsOut.push( ny1 );		normsOut.push( nz1 );
		normsOut.push( nx2 );		normsOut.push( ny2 );		normsOut.push( nz2 );
		normsOut.push( nx2 );		normsOut.push( ny2 );		normsOut.push( nz2 );
		normsOut.push( nx0 );		normsOut.push( ny0 );		normsOut.push( nz0 );

		uvsOut.push( u0 );		uvsOut.push( v0 );
		uvsOut.push( u1 );		uvsOut.push( v1 );
		uvsOut.push( u1 );		uvsOut.push( v1 );
		uvsOut.push( u2 );		uvsOut.push( v2 );
		uvsOut.push( u2 );		uvsOut.push( v2 );
		uvsOut.push( u0 );		uvsOut.push( v0 );

		iTriangle++;
		index += 3;
		nVertices += 6;
	}

	return nVertices;
};



if (typeof exports === "object") {
    exports.ShapePrimitive = ShapePrimitive;
}