示例#1
0
        public override FScheme.Value Evaluate(FSharpList <FScheme.Value> args)
        {
            var input = args[0];

            //If we are receiving a list, we must create levels for each double in the list.
            if (input.IsList)
            {
                throw new NotImplementedException();
            }
            //If we're not receiving a list, we will just assume we received one double height.
            else
            {
                double x = ((FScheme.Value.Number)input).Item;

                int    i0 = SimplexHelper.FastFloor(x);
                int    i1 = i0 + 1;
                double x0 = x - i0;
                double x1 = x0 - 1.0f;

                double n0, n1;

                double t0 = 1.0f - x0 * x0;
                t0 *= t0;
                n0  = t0 * t0 * SimplexHelper.Grad(SimplexHelper.perm[i0 & 0xff], x0);

                double t1 = 1.0f - x1 * x1;
                t1 *= t1;
                n1  = t1 * t1 * SimplexHelper.Grad(SimplexHelper.perm[i1 & 0xff], x1);
                // The maximum value of this noise is 8*(3/4)^4 = 2.53125
                // A factor of 0.395 scales to fit exactly within [-1,1]
                return(FScheme.Value.NewNumber(0.395f * (n0 + n1)));
            }
        }
示例#2
0
        public override FScheme.Value Evaluate(FSharpList <FScheme.Value> args)
        {
            var xinput = args[0];
            var yinput = args[1];
            var zinput = args[2];



            //If we are receiving a list, we must create levels for each double in the list.
            if (xinput.IsList || yinput.IsList || zinput.IsList)
            {
                throw new NotImplementedException();
            }
            //If we're not receiving a list, we will just assume we received one double height.
            else
            {
                double x = ((FScheme.Value.Number)xinput).Item;
                double y = ((FScheme.Value.Number)yinput).Item;
                double z = ((FScheme.Value.Number)zinput).Item;


                // Simple skewing factors for the 3D case
                const double F3 = 0.333333333f;
                const double G3 = 0.166666667f;

                double n0, n1, n2, n3; // Noise contributions from the four corners

                // Skew the input space to determine which simplex cell we're in
                double s  = (x + y + z) * F3; // Very nice and simple skew factor for 3D
                double xs = x + s;
                double ys = y + s;
                double zs = z + s;
                int    i  = SimplexHelper.FastFloor(xs);
                int    j  = SimplexHelper.FastFloor(ys);
                int    k  = SimplexHelper.FastFloor(zs);

                double t  = (double)(i + j + k) * G3;
                double X0 = i - t; // Unskew the cell origin back to (x,y,z) space
                double Y0 = j - t;
                double Z0 = k - t;
                double x0 = x - X0; // The x,y,z distances from the cell origin
                double y0 = y - Y0;
                double z0 = z - Z0;

                // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
                // Determine which simplex we are in.
                int i1, j1, k1; // Offsets for second corner of simplex in (i,j,k) coords
                int i2, j2, k2; // Offsets for third corner of simplex in (i,j,k) coords

                /* This code would benefit from a backport from the GLSL version! */
                if (x0 >= y0)
                {
                    if (y0 >= z0)
                    {
                        i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
                    }                                                   // X Y Z order
                    else if (x0 >= z0)
                    {
                        i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1;
                    }                                                                      // X Z Y order
                    else
                    {
                        i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1;
                    }                                                        // Z X Y order
                }
                else
                { // x0<y0
                    if (y0 < z0)
                    {
                        i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1;
                    }                                                                // Z Y X order
                    else if (x0 < z0)
                    {
                        i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1;
                    }                                                                     // Y Z X order
                    else
                    {
                        i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
                    }                                                        // Y X Z order
                }

                // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
                // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
                // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
                // c = 1/6.

                double x1 = x0 - i1 + G3; // Offsets for second corner in (x,y,z) coords
                double y1 = y0 - j1 + G3;
                double z1 = z0 - k1 + G3;
                double x2 = x0 - i2 + 2.0f * G3; // Offsets for third corner in (x,y,z) coords
                double y2 = y0 - j2 + 2.0f * G3;
                double z2 = z0 - k2 + 2.0f * G3;
                double x3 = x0 - 1.0f + 3.0f * G3; // Offsets for last corner in (x,y,z) coords
                double y3 = y0 - 1.0f + 3.0f * G3;
                double z3 = z0 - 1.0f + 3.0f * G3;

                // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
                int ii = i % 256;
                int jj = j % 256;
                int kk = k % 256;

                // Calculate the contribution from the four corners
                double t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0;
                if (t0 < 0.0f)
                {
                    n0 = 0.0f;
                }
                else
                {
                    t0 *= t0;
                    n0  = t0 * t0 * SimplexHelper.Grad(SimplexHelper.perm[ii + SimplexHelper.perm[jj + SimplexHelper.perm[kk]]], x0, y0, z0);
                }

                double t1 = 0.6f - x1 * x1 - y1 * y1 - z1 * z1;
                if (t1 < 0.0f)
                {
                    n1 = 0.0f;
                }
                else
                {
                    t1 *= t1;
                    n1  = t1 * t1 * SimplexHelper.Grad(SimplexHelper.perm[ii + i1 + SimplexHelper.perm[jj + j1 + SimplexHelper.perm[kk + k1]]], x1, y1, z1);
                }

                double t2 = 0.6f - x2 * x2 - y2 * y2 - z2 * z2;
                if (t2 < 0.0f)
                {
                    n2 = 0.0f;
                }
                else
                {
                    t2 *= t2;
                    n2  = t2 * t2 * SimplexHelper.Grad(SimplexHelper.perm[ii + i2 + SimplexHelper.perm[jj + j2 + SimplexHelper.perm[kk + k2]]], x2, y2, z2);
                }

                double t3 = 0.6f - x3 * x3 - y3 * y3 - z3 * z3;
                if (t3 < 0.0f)
                {
                    n3 = 0.0f;
                }
                else
                {
                    t3 *= t3;
                    n3  = t3 * t3 * SimplexHelper.Grad(SimplexHelper.perm[ii + 1 + SimplexHelper.perm[jj + 1 + SimplexHelper.perm[kk + 1]]], x3, y3, z3);
                }

                // Add contributions from each corner to get the final noise value.
                // The result is scaled to stay just inside [-1,1]
                return(FScheme.Value.NewNumber(32.0f * (n0 + n1 + n2 + n3))); // TODO: The scale factor is preliminary!
            }
        }
示例#3
0
        public override FScheme.Value Evaluate(FSharpList <FScheme.Value> args)
        {
            var xinput = args[0];
            var yinput = args[1];



            //If we are receiving a list, we must create levels for each double in the list.
            if (xinput.IsList || yinput.IsList)
            {
                throw new NotImplementedException();
            }
            //If we're not receiving a list, we will just assume we received one double height.
            else
            {
                double x = ((FScheme.Value.Number)xinput).Item;
                double y = ((FScheme.Value.Number)yinput).Item;


                const double F2 = 0.366025403f; // F2 = 0.5*(sqrt(3.0)-1.0)
                const double G2 = 0.211324865f; // G2 = (3.0-Math.sqrt(3.0))/6.0

                double n0, n1, n2;              // Noise contributions from the three corners

                // Skew the input space to determine which simplex cell we're in
                double s  = (x + y) * F2; // Hairy factor for 2D
                double xs = x + s;
                double ys = y + s;
                int    i  = SimplexHelper.FastFloor(xs);
                int    j  = SimplexHelper.FastFloor(ys);

                double t  = (double)(i + j) * G2;
                double X0 = i - t;  // Unskew the cell origin back to (x,y) space
                double Y0 = j - t;
                double x0 = x - X0; // The x,y distances from the cell origin
                double y0 = y - Y0;

                // For the 2D case, the simplex shape is an equilateral triangle.
                // Determine which simplex we are in.
                int i1, j1; // Offsets for second (middle) corner of simplex in (i,j) coords
                if (x0 > y0)
                {
                    i1 = 1; j1 = 0;
                }                                // lower triangle, XY order: (0,0)->(1,0)->(1,1)
                else
                {
                    i1 = 0; j1 = 1;
                }                             // upper triangle, YX order: (0,0)->(0,1)->(1,1)

                // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
                // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
                // c = (3-sqrt(3))/6

                double x1 = x0 - i1 + G2;          // Offsets for middle corner in (x,y) unskewed coords
                double y1 = y0 - j1 + G2;
                double x2 = x0 - 1.0f + 2.0f * G2; // Offsets for last corner in (x,y) unskewed coords
                double y2 = y0 - 1.0f + 2.0f * G2;

                // Wrap the integer indices at 256, to avoid indexing perm[] out of bounds
                int ii = i % 256;
                int jj = j % 256;

                // Calculate the contribution from the three corners
                double t0 = 0.5f - x0 * x0 - y0 * y0;
                if (t0 < 0.0f)
                {
                    n0 = 0.0f;
                }
                else
                {
                    t0 *= t0;
                    n0  = t0 * t0 * SimplexHelper.Grad(SimplexHelper.perm[ii + SimplexHelper.perm[jj]], x0, y0);
                }

                double t1 = 0.5f - x1 * x1 - y1 * y1;
                if (t1 < 0.0f)
                {
                    n1 = 0.0f;
                }
                else
                {
                    t1 *= t1;
                    n1  = t1 * t1 * SimplexHelper.Grad(SimplexHelper.perm[ii + i1 + SimplexHelper.perm[jj + j1]], x1, y1);
                }

                double t2 = 0.5f - x2 * x2 - y2 * y2;
                if (t2 < 0.0f)
                {
                    n2 = 0.0f;
                }
                else
                {
                    t2 *= t2;
                    n2  = t2 * t2 * SimplexHelper.Grad(SimplexHelper.perm[ii + 1 + SimplexHelper.perm[jj + 1]], x2, y2);
                }

                // Add contributions from each corner to get the final noise value.
                // The result is scaled to return values in the interval [-1,1].
                return(FScheme.Value.NewNumber(40.0f * (n0 + n1 + n2))); // TODO: The scale factor is preliminary!
            }
        }