cellShader/cellShader.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.
// ==========================================================================
//+

// DESCRIPTION: 
//  3D cell texture plugin node for Maya
//  Produces dependency graph node Cells

// This node is an example of a solid texture that divides 3D space into cells.
//
// Inputs:
//  colorOffset - output color offset
//  colorGain   - output color scale
//  pointWorld  - world space sample point
//  placementMatrix - world to texture space transform
//
// Output:
//  F0      - distance to nearest cell center
//  F1      - distance to 2nd nearest cell center
//  borderDistance  - distance to border
//  N0      - index of cell containing sample point
//  outColor    - colorGain * F0 + colorOffset

// To use this shader, create a Cell node and connect its output to an input of a surface/shader node such as Color. 
//

#include <math.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>

#ifdef LINUX
#define fsqrt   sqrtf
#include <stdlib.h>
#endif

class R3 {
    public:
    R3(float a, float b, float c): x(a), y(b), z(c) {}
    R3() {}
    public:
    float x;
    float y;
    float z;
};

static void initCellFunc();
static void cellFunc(const R3 &, float &n0, float &f1, float &f2);


class Cell3D : public MPxNode
{
public:
                    Cell3D();
            ~Cell3D() override;

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

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

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

    private:

    // Input attributes
    static MObject  aColorGain;
    static MObject  aColorOffset;
    static MObject  aPointWorld;
    static MObject  aPlaceMat;

    // Output attributes
    static MObject  aOutColor;
    static MObject  aOutAlpha;
    static MObject  aOutF0;
    static MObject  aOutF1;
    static MObject  aOutN0;
    static MObject  aOutBorderDist;
};

// Static data
MTypeId Cell3D::id(0x81017);

// Attributes

MObject Cell3D::aColorGain;
MObject Cell3D::aColorOffset;
MObject Cell3D::aOutF0;
MObject Cell3D::aOutF1;
MObject Cell3D::aOutN0;
MObject Cell3D::aOutBorderDist;
MObject Cell3D::aPointWorld;
MObject Cell3D::aPlaceMat;

MObject Cell3D::aOutColor;
MObject Cell3D::aOutAlpha;

#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 Cell3D::postConstructor( )
{
    setMPSafe(true);
}

//
// DESCRIPTION:
Cell3D::Cell3D()
{
}

//
// DESCRIPTION:
Cell3D::~Cell3D()
{
}

//
// DESCRIPTION:
void * Cell3D::creator()
{
    return new Cell3D();
}

//
// DESCRIPTION:
MStatus Cell3D::initialize()
{
    MFnMatrixAttribute mAttr;
    MFnNumericAttribute nAttr; 

    // Input attributes

    aColorGain = nAttr.createColor("colorGain", "cg");
    MAKE_INPUT(nAttr);
    CHECK_MSTATUS( nAttr.setDefault(1.0f,1.0f,1.0f) );

    aColorOffset = nAttr.createColor("colorOffset", "co");
    MAKE_INPUT(nAttr);
    
    aPlaceMat = mAttr.create("placementMatrix", "pm", 
                             MFnMatrixAttribute::kFloat);
    MAKE_INPUT(mAttr);

    // Implicit shading network attributes

    aPointWorld = nAttr.createPoint("pointWorld", "pw");
    MAKE_INPUT(nAttr);
    CHECK_MSTATUS( nAttr.setHidden(true) );

    // Create output attributes

    aOutF0 = nAttr.create( "F0", "f0", MFnNumericData::kFloat);
    MAKE_OUTPUT(nAttr);

    aOutF1 = nAttr.create( "F1", "f1", MFnNumericData::kFloat);
    MAKE_OUTPUT(nAttr);

    aOutN0 = nAttr.create( "N0", "n0", MFnNumericData::kFloat);
    MAKE_OUTPUT(nAttr);

    aOutBorderDist = nAttr.create("borderDistance", "bd", 
                                  MFnNumericData::kFloat);
    MAKE_OUTPUT(nAttr);
    
    aOutColor = nAttr.createColor("outColor", "oc");
    MAKE_OUTPUT(nAttr);

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

    // Add attributes to the node database.

    CHECK_MSTATUS( addAttribute(aColorGain) );
    CHECK_MSTATUS( addAttribute(aColorOffset) );
    CHECK_MSTATUS( addAttribute(aPointWorld) );
    CHECK_MSTATUS( addAttribute(aPlaceMat) );

    CHECK_MSTATUS( addAttribute(aOutAlpha) );
    CHECK_MSTATUS( addAttribute(aOutColor) );
    CHECK_MSTATUS( addAttribute(aOutF0) );
    CHECK_MSTATUS( addAttribute(aOutF1) );
    CHECK_MSTATUS( addAttribute(aOutN0) );
    CHECK_MSTATUS( addAttribute(aOutBorderDist) );

    // All input affect the output color and alpha

    CHECK_MSTATUS( attributeAffects (aColorGain, aOutColor) );
    CHECK_MSTATUS( attributeAffects (aColorOffset, aOutColor) );
    CHECK_MSTATUS( attributeAffects (aPlaceMat, aOutColor) );
    CHECK_MSTATUS( attributeAffects (aPointWorld, aOutColor) );

    CHECK_MSTATUS( attributeAffects (aColorGain, aOutAlpha) );
    CHECK_MSTATUS( attributeAffects (aColorOffset, aOutAlpha) );
    CHECK_MSTATUS( attributeAffects (aPlaceMat, aOutAlpha) );
    CHECK_MSTATUS( attributeAffects (aPointWorld, aOutAlpha) );

    // Geometry attribute affect all other outputs.

    CHECK_MSTATUS( attributeAffects (aPlaceMat, aOutF0) );
    CHECK_MSTATUS( attributeAffects (aPointWorld, aOutF0) );

    CHECK_MSTATUS( attributeAffects (aPlaceMat, aOutF1) );
    CHECK_MSTATUS( attributeAffects (aPointWorld, aOutF1) );

    CHECK_MSTATUS( attributeAffects (aPlaceMat, aOutN0) );
    CHECK_MSTATUS( attributeAffects (aPointWorld, aOutN0) );

    CHECK_MSTATUS( attributeAffects (aPlaceMat, aOutBorderDist) );
    CHECK_MSTATUS( attributeAffects (aPointWorld, aOutBorderDist) );

    return MS::kSuccess;
}


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

MStatus Cell3D::compute(const MPlug& plug, MDataBlock& block) 
{
    if ( (plug != aOutColor) && (plug.parent() != aOutColor) &&
         (plug != aOutAlpha) &&
         (plug != aOutBorderDist) && 
         (plug != aOutF0) && (plug != aOutF1) && (plug != aOutN0)
       ) 
       return MS::kUnknownParameter;

    const float3& worldPos = block.inputValue(aPointWorld).asFloat3();
    const MFloatMatrix& m = block.inputValue(aPlaceMat).asFloatMatrix();
    const MFloatVector& cGain = block.inputValue(aColorGain).asFloatVector();
    const MFloatVector& cOff = block.inputValue(aColorOffset).asFloatVector();
    
    MFloatPoint q(worldPos[0], worldPos[1], worldPos[2]);
    q *= m;                                 // Convert into solid space
    
    float n0, f0, f1;
    cellFunc(R3(q.x, q.y, q.z), n0, f0, f1);

    MDataHandle outHandle = block.outputValue(aOutF0);
    outHandle.asFloat() = f0;
    outHandle.setClean();

    outHandle = block.outputValue(aOutF1);
    outHandle.asFloat() = f1;
    outHandle.setClean();

    outHandle = block.outputValue(aOutN0);
    outHandle.asFloat() = n0;
    outHandle.setClean();

    outHandle = block.outputValue(aOutBorderDist);
    outHandle.asFloat() = 0.5f*(f1 - f0);
    outHandle.setClean();

    outHandle = block.outputValue( aOutColor );
    MFloatVector & outColor = outHandle.asFloatVector();
    outColor = cGain * f0 + cOff;
    outHandle.setClean();

    outHandle = block.outputValue(aOutAlpha);
    outHandle.asFloat() = f0;
    outHandle.setClean();

    return MS::kSuccess;
}

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

    MFnPlugin plugin( obj, PLUGIN_COMPANY, "4.5", "Any" );
    CHECK_MSTATUS( plugin.registerNode("cells", Cell3D::id,
                        Cell3D::creator, Cell3D::initialize,
                        MPxNode::kDependNode, &UserClassify) );

    initCellFunc();
    
    return MS::kSuccess;
}

// DESCRIPTION:
MStatus uninitializePlugin( MObject obj )
{
    MFnPlugin plugin( obj );
    CHECK_MSTATUS( plugin.deregisterNode( Cell3D::id ) );

    return MS::kSuccess;
}


#define N_CELLS 1000

static int permuteTable[N_CELLS*2];

//
// Initialize permutation table used by fold()
// 

static void initPermute()
{
    int i;
    for (i = 0; i < N_CELLS; ++i) {
        permuteTable[i] = i;
    }
    for (i = N_CELLS - 1; i >= 1; --i) {
        int n = lrand48() % (i + 1);
        int tmp = permuteTable[n];
        permuteTable[n] = permuteTable[i];
        permuteTable[i] = tmp;
    }
    for (i = 0; i < N_CELLS; ++i) {
        permuteTable[i + N_CELLS] = permuteTable[i];
    }
}

//
// Fold is a pseudo-random function mapping 3 integers
// into a single integer in the range [0, (N_CELLS-1)].

static int fold(int i, int j, int k)
{
    //i %= N_CELLS; j %= N_CELLS; k %= N_CELLS;
    if (i < 0) i = (i + N_CELLS*(i/N_CELLS + 1)) % N_CELLS;
    else i %= N_CELLS;
    if (j < 0) j = (j + N_CELLS*(j/N_CELLS + 1)) % N_CELLS;
    else j %= N_CELLS;
    if (k < 0) k = (k + N_CELLS*(k/N_CELLS + 1)) % N_CELLS;
    else k %= N_CELLS;

    return permuteTable[permuteTable[permuteTable[i] + j] + k];
}

#define N_CELLS 1000

static R3 CellSampleTable[N_CELLS];

static void initCellFunc()
{
    int i;
    srand48(10);                            // Make sure we always
                                            // compute the same random
                                            // numbers.
    for (i = 0; i < N_CELLS; ++i) {
    CellSampleTable[i] = R3((float)drand48(),
                            (float)drand48(),
                            (float)drand48());
    }
    initPermute();
}

static inline float sqr(float t) { return t*t; }

static inline float distance2(const R3 &a, const R3 &b)
{ 
    float t = sqr(b.x - a.x) + sqr(b.y - a.y) + sqr(b.z - a.z);
    return t;
}

static void cellFunc(const R3 &p, float &n0, float &f0, float &f1)
{
    R3 q = p;
    int i = (int)floorf(q.x);
    int j = (int)floorf(q.y);
    int k = (int)floorf(q.z);
    q.x -= i;
    q.y -= j;
    q.z -= k;
    int index = fold(i,j,k);
    float minDist = distance2(CellSampleTable[index], q);
    float minDist2 = 2.0;
    int k0;
    k0 = index;
    
    // easy but slow way, check distance to point in each adjacent 
    // cell to find closest and second closest.
    R3 q1;
    for (int ii = -1; ii <= 1; ++ii) {
        q1.x = q.x - ii;
        int i1 = i + ii;
        for (int jj = -1; jj <= 1; ++jj) {
            q1.y = q.y - jj;
            int j1 = j + jj;
            for (int kk = -1; kk <= 1; ++kk) {
                if (!ii && !jj && !kk) continue;
                q1.z = q.z - kk;
                int k1 = k + kk;
                index = fold(i1, j1, k1);
                float t = distance2(CellSampleTable[index], q1);
                if (minDist > t) {
                    minDist2 = minDist;
                    minDist = t;
                    k0 = index;
                }
                else if (minDist2 > t) {
                    minDist2 = t;
                }
            }
        }
    }
    f0 = sqrtf(minDist);
    f1 = sqrtf(minDist2);
    n0 = k0/(float)(N_CELLS);
}