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# flameShader.cpp

    //-
    // ==========================================================================
    // Copyright 1995,2006,2008 Autodesk, Inc. All rights reserved.
    //
    // Use of this software is subject to the terms of the Autodesk
    // license agreement provided at the time of installation or download,
    // or which otherwise accompanies this software in either electronic
    // or hard copy form.
    // ==========================================================================
    //+

    #include <math.h>
    #include <stdlib.h>

    #include <maya/MPxNode.h>
    #include <maya/MIOStream.h>
    #include <maya/MString.h>
    #include <maya/MTypeId.h>
    #include <maya/MPlug.h>
    #include <maya/MDataBlock.h>
    #include <maya/MDataHandle.h>
    #include <maya/MFnNumericAttribute.h>
    #include <maya/MFnMatrixAttribute.h>
    #include <maya/MFloatVector.h>
    #include <maya/MFloatPoint.h>
    #include <maya/MFnPlugin.h>

    // Local functions
    float Noise(float, float, float);
    void  Noise_init();
    static float Omega(int i, int j, int k, float t[3]);
    static float omega(float);
    static double turbulence(double u,double v,double w,int octaves);

    #define PI                  3.14159265358979323846

    #ifdef FLOOR
    #undef FLOOR
    #endif
    #define FLOOR(x)            ((int)floorf(x))

    #define TABLELEN            512
    #define TLD2                256    // TABLELEN

    // Local variables
    static int                  Phi[TABLELEN];
    static char                 fPhi[TABLELEN];
    static float                G[TABLELEN][3];

    class Flame3D : public MPxNode
    {
        public:
                        Flame3D();
        virtual         ~Flame3D();

        virtual MStatus compute( const MPlug&, MDataBlock& );
        virtual void    postConstructor();

        static  void *  creator();
        static  MStatus initialize();

        //  Id tag for use with binary file format
        static  MTypeId id;

        private:

        // Input attributes
        static MObject  aColorBase;
        static MObject  aColorFlame;
        static MObject  aRiseSpeed;
        static MObject  aFlickerSpeed;
        static MObject  aFlickerDeform;
        static MObject  aFlamePow;
        static MObject  aFlameFrame;
        static MObject  aRiseAxis;
        static MObject  aPlaceMat;
        static MObject  aPointWorld;

        // Output attributes
        static MObject  aOutAlpha;
        static MObject  aOutColor;
    };

    // Static data
    MTypeId Flame3D::id(0x81016);

    // Attributes
    MObject  Flame3D::aColorBase;
    MObject  Flame3D::aColorFlame;
    MObject  Flame3D::aRiseSpeed;
    MObject  Flame3D::aFlickerSpeed;
    MObject  Flame3D::aFlickerDeform;
    MObject  Flame3D::aFlamePow;
    MObject  Flame3D::aFlameFrame;
    MObject  Flame3D::aRiseAxis;
    MObject  Flame3D::aPointWorld;
    MObject  Flame3D::aPlaceMat;

    MObject  Flame3D::aOutAlpha;
    MObject  Flame3D::aOutColor;

    #define MAKE_INPUT(attr)    \
        CHECK_MSTATUS(attr.setKeyable(true));       \
        CHECK_MSTATUS(attr.setStorable(true));      \
        CHECK_MSTATUS(attr.setReadable(true));      \
        CHECK_MSTATUS(attr.setWritable(true));

    #define MAKE_OUTPUT(attr)   \
        CHECK_MSTATUS(attr.setKeyable(false));      \
        CHECK_MSTATUS(attr.setStorable(false));     \
        CHECK_MSTATUS(attr.setReadable(true));      \
        CHECK_MSTATUS(attr.setWritable(false));

    //
    // DESCRIPTION:
    void Flame3D::postConstructor( )
    {
        setMPSafe(true);
    }

    //
    // DESCRIPTION:
    Flame3D::Flame3D()
    {
    }

    //
    // DESCRIPTION:
    Flame3D::~Flame3D()
    {
    }

    //
    // DESCRIPTION:
    void * Flame3D::creator()
    {
        return new Flame3D();
    }

    //
    // DESCRIPTION:
    MStatus Flame3D::initialize()
    {
        MFnMatrixAttribute mAttr;
        MFnNumericAttribute nAttr;

        // Create input attributes
        aRiseSpeed = nAttr.create( "Rise", "rs", MFnNumericData::kFloat);
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(0.1f));
        CHECK_MSTATUS(nAttr.setMin(0.0f));
        CHECK_MSTATUS(nAttr.setMax(1.0f));

        aFlickerSpeed = nAttr.create( "Speed", "s", MFnNumericData::kFloat);
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(0.1f));
        CHECK_MSTATUS(nAttr.setMin(0.0f));
        CHECK_MSTATUS(nAttr.setMax(1.0f));

        aFlickerDeform = nAttr.create( "Flicker", "f", MFnNumericData::kFloat);
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(0.5f));
        CHECK_MSTATUS(nAttr.setMin(0.0f));
        CHECK_MSTATUS(nAttr.setMax(1.0f));

        aFlamePow = nAttr.create( "Power", "pow", MFnNumericData::kFloat);
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(1.0f));
        CHECK_MSTATUS(nAttr.setMin(0.0f));
        CHECK_MSTATUS(nAttr.setMax(1.0f));

        aFlameFrame = nAttr.create( "Frame", "fr", MFnNumericData::kFloat);
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(1.0f));
        CHECK_MSTATUS(nAttr.setMin(0.0f));
        CHECK_MSTATUS(nAttr.setMax(1000.0f));

        aRiseAxis = nAttr.createPoint( "Axis", "a");
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(0., 1., 0.));

        aColorBase = nAttr.createColor("ColorBase", "cg");
        MAKE_INPUT(nAttr);

        aColorFlame = nAttr.createColor("ColorFlame", "cb");
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setDefault(1., 1., 1.));

        aPlaceMat = mAttr.create("placementMatrix", "pm",
                                 MFnMatrixAttribute::kFloat);
        MAKE_INPUT(mAttr);

        // Internal shading attribute, implicitely connected.
        aPointWorld = nAttr.createPoint("pointWorld", "pw");
        MAKE_INPUT(nAttr);
        CHECK_MSTATUS(nAttr.setHidden(true));

        // Create output attributes
        aOutColor  = nAttr.createColor("outColor",  "oc");
        MAKE_OUTPUT(nAttr);

        aOutAlpha = nAttr.create( "outAlpha", "oa", MFnNumericData::kFloat);
        MAKE_OUTPUT(nAttr);

        // Add the attributes here
        CHECK_MSTATUS(addAttribute(aColorBase));
        CHECK_MSTATUS(addAttribute(aColorFlame));
        CHECK_MSTATUS(addAttribute(aRiseSpeed));
        CHECK_MSTATUS(addAttribute(aFlickerSpeed));
        CHECK_MSTATUS(addAttribute(aFlickerDeform));
        CHECK_MSTATUS(addAttribute(aFlamePow));
        CHECK_MSTATUS(addAttribute(aFlameFrame));
        CHECK_MSTATUS(addAttribute(aRiseAxis));
        CHECK_MSTATUS(addAttribute(aPointWorld));
        CHECK_MSTATUS(addAttribute(aPlaceMat));

        CHECK_MSTATUS(addAttribute(aOutAlpha));
        CHECK_MSTATUS(addAttribute(aOutColor));

        // All input affect the output color and alpha
        CHECK_MSTATUS(attributeAffects (aColorBase, aOutColor));
        CHECK_MSTATUS(attributeAffects(aColorBase, aOutAlpha));

        CHECK_MSTATUS(attributeAffects (aColorFlame, aOutColor));
        CHECK_MSTATUS(attributeAffects(aColorFlame, aOutAlpha));

        CHECK_MSTATUS(attributeAffects(aRiseSpeed, aOutColor));
        CHECK_MSTATUS(attributeAffects(aRiseSpeed, aOutAlpha));

        CHECK_MSTATUS(attributeAffects(aFlickerSpeed, aOutColor));
        CHECK_MSTATUS(attributeAffects(aFlickerSpeed, aOutAlpha));

        CHECK_MSTATUS(attributeAffects(aFlickerDeform, aOutColor));
        CHECK_MSTATUS(attributeAffects(aFlickerDeform, aOutAlpha));

        CHECK_MSTATUS(attributeAffects(aFlamePow, aOutColor));
        CHECK_MSTATUS(attributeAffects(aFlamePow, aOutAlpha));

        CHECK_MSTATUS(attributeAffects(aFlameFrame, aOutColor));
        CHECK_MSTATUS(attributeAffects(aFlameFrame, aOutAlpha));

        CHECK_MSTATUS(attributeAffects(aRiseAxis, aOutColor));
        CHECK_MSTATUS(attributeAffects(aRiseAxis, aOutAlpha));

        CHECK_MSTATUS(attributeAffects(aPointWorld, aOutColor));
        CHECK_MSTATUS(attributeAffects (aPointWorld, aOutAlpha));

        CHECK_MSTATUS(attributeAffects(aPlaceMat, aOutColor));
        CHECK_MSTATUS(attributeAffects(aPlaceMat, aOutAlpha));

        return MS::kSuccess;
    }

    // DESCRIPTION:
    // This function gets called by Maya to evaluate the texture.
    //

    MStatus Flame3D::compute(const MPlug& plug, MDataBlock& block)
    {
        // outColor or individial R, G, B channel, or alpha
        if((plug != aOutColor) && (plug.parent() != aOutColor) &&
           (plug != aOutAlpha))
           return MS::kUnknownParameter;

        float3 & worldPos = block.inputValue( aPointWorld).asFloat3();
        const MFloatMatrix& mat = block.inputValue(aPlaceMat).asFloatMatrix();
        const MFloatVector& cBase = block.inputValue(aColorBase).asFloatVector();
        const MFloatVector& cFlame=block.inputValue(aColorFlame).asFloatVector();
        const MFloatVector& axis = block.inputValue( aRiseAxis ).asFloatVector();
        const float rise_speed = block.inputValue( aRiseSpeed ).asFloat();
        const float flicker_speed = block.inputValue( aFlickerSpeed ).asFloat();
        const float dscale = block.inputValue( aFlickerDeform ).asFloat();
        const float frame = block.inputValue( aFlameFrame ).asFloat();
        const float power = block.inputValue( aFlamePow ).asFloat();

        MFloatPoint q(worldPos[0], worldPos[1], worldPos[2]);
        q *= mat;                               // Convert into solid space

        // Offset texture coord along the RiseAxis
        float rise_distance = -1.0f * rise_speed * frame;
        float u,v,w;
        u = q.x + ( rise_distance * axis[0]);
        v = q.y + ( rise_distance * axis[1]);
        w = q.z + ( rise_distance * axis[2]);

        // Generate a displaced point by moving along the
        // displacement vector (currently the 1,1,1 vector)
        // based on flicker speed.
        float dist = flicker_speed * frame;
        float au, av, aw;
        au = u + dist;
        av = v + dist;
        aw = w + dist;

        // Calculate 3 noise values
        float ascale = Noise(au,av,aw);
        // float bscale = Noise(au,-av,aw);
        // float cscale = Noise(-au,av,-aw);

        // add this noise as a vector to the texture coordinates
        // (since we are only calculating one value, the
        // displacement will be along the 1 1 1 vector ... this
        // displacement generates the "flicker" movement as the
        // value moves around the texture coordinate

        u += ascale * dscale;
        v += ascale * dscale;
        w += ascale * dscale;

        // Calculate a turbulence value for this point

        float scalar = (float) (turbulence(u, v, w, 3) + 0.5);

        // convert scalar into a point on the color curve

        if (power != 1) scalar = powf (scalar, power);

        MFloatVector resultColor;
        if (scalar >= 1)
            resultColor = cFlame;
        else if (scalar < 0)
            resultColor = cBase;
        else
            resultColor = ((cFlame-cBase)*scalar) + cBase;

        MDataHandle outHandle = block.outputValue( aOutColor );
        MFloatVector & outColor = outHandle.asFloatVector();
        outColor = resultColor;
        outHandle.setClean();

        outHandle = block.outputValue(aOutAlpha);
        outHandle.asFloat() = scalar;
        outHandle.setClean();

        return MS::kSuccess;
    }

    MStatus initializePlugin( MObject obj )
    {
        const MString UserClassify( "texture/3d" );

        MFnPlugin plugin( obj, PLUGIN_COMPANY, "3.0", "Any" );
        CHECK_MSTATUS( plugin.registerNode( "flame", Flame3D::id,
            Flame3D::creator, Flame3D::initialize,
            MPxNode::kDependNode, &UserClassify) );

        Noise_init();

        return MS::kSuccess;
    }

    // DESCRIPTION:
    MStatus uninitializePlugin( MObject obj )
    {
        MFnPlugin plugin( obj );
        CHECK_MSTATUS( plugin.deregisterNode( Flame3D::id ) );

        return MS::kSuccess;
    }

    //
    //  REFERENCES:
    //      Perlin, K. An Image Synthesizer, Computer Graphics,
    //      Vol. 19, No. 3, July 1985.
    //
    //      Perlin, K., Hoffert, E.M., Hypertexture, Computer Graphics,
    //      Vol. 23, No. 3, July 1989.
    //

    float Noise(float u, float v, float w)
    {
        int         i;
        int         j;
        int         k;
        int         ul;
        int         vl;
        int         wl;
        float       ans;
        float       t[3];

        ans = 0.0;
        ul  = FLOOR(u);
        vl  = FLOOR(v);
        wl  = FLOOR(w);

        for(i = ul + 1; i >= ul; i--)
        {
            t[0] = u - i;
            for(j = vl + 1; j >= vl; j--)
            {
                t[1] = v - j;
                for(k = wl + 1; k >= wl; k--)
                {
                    t[2] = w - k;
                    ans += Omega(i, j, k, t);
                }
            }
        }

        return ans;
    }

    static float Omega(int i, int j, int k, float t[3])
    {
        int ct;

        ct = Phi[((i +
             Phi[((j +
             Phi[(k%TLD2)+TLD2]) % TLD2) + TLD2]) % TLD2) + TLD2];

        return omega(t[0]) * omega(t[1]) * omega(t[2]) *
            ( G[ct][0]*t[0] + G[ct][1]*t[1] + G[ct][2]*t[2] );
    }

    static float omega(float t)
    {
        t  = fabsf(t);
        return (t * (t * (t * (float)2.0 - (float)3.0))) + (float)1.0;
    }

    void Noise_init()
    {
        int i;
        float u, v, w, s, len;
        static int first_time = 1;

        if (first_time)
            first_time = 0;
        else
            return;

        (void)srand48(0l);

        for(i = 0; i < TABLELEN; i++)
            fPhi[i] = 0;

        for(i = 0; i < TABLELEN; i++) {
            Phi[i] = lrand48() % TABLELEN;

            if (fPhi[Phi[i]])
                i--;
            else
                fPhi[Phi[i]] = 1;
        }
        for(i = 0; i < TABLELEN; i++) {
            u = (float) (2.0 * drand48() - 1.0);
            v = (float) (2.0 * drand48() - 1.0);
            w = (float) (2.0 * drand48() - 1.0);
            if((s = u*u + v*v + w*w) > 1.0)
            {   i--;
            continue;
            }
            else
                if (s == 0.0)
                {   i--;
                continue;
                }

            len = 1.0f / sqrtf(s);
            G[i][0] = u * len;
            G[i][1] = v * len;
            G[i][2] = w * len;
        }
    }

    static double turbulence(double u,double v,double w,int octaves)
    {
        double s,t;
        s = 1.0;
        t = 0.0;

        while (octaves--) {
            t += Noise((float)u, (float)v, (float)w)*s;
            s *= 0.5;
            u*=2.0; v*=2.0; w*=2.0;
        }
        return t;
    }