CH/CH_Support.h

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/*
// PROPRIETARY INFORMATION.  This software is proprietary to
// Side Effects Software Inc., and is not to be reproduced,
// transmitted, or disclosed in any way without written permission.
//
// Produced by:
//      Mark Elendt
//      Side Effects Software Inc.
//      20 Maud St.
//      Toronto, Ontario,  M5V 2M5
//      Canada
//      416-366-4607
//
// NAME:        Channel Library (C++)
//
// COMMENTS:    Support glue between channel and expression libraries
//
*/

#ifndef __CH_Support_h__
#define __CH_Support_h__

#include "CH_API.h"
//
//  Some defines for expressions.  These defines may be used by anyone
//      who needs them.  They are the lower bits in the EV_Expression
//      flag and are accessible by the method for getting flags in the
//      CH_Expression class. Some (CH_SYM...) are flags for the EV_SYMBOL,
//      which are or'ed into the expression flags and so must use the
//      same bit-range.
//

#define CH_EXPRTIME      0x00008000     // Expression uses time
#define CH_EXPRCHAN      0x00010000     // Expression uses channel
#define CH_EXPRIVALUE    0x00020000     // Expression uses in value
#define CH_EXPROVALUE    0x00040000     // Expression uses out value
#define CH_EXPRSLOPE     0x00080000     // Expression uses in slope/out slope
//#define CH_EXPRPARAM   0x00100000     // Now Unused, free for use
#define CH_EXPRACCEL     0x00200000     // Expression uses in accel/out accel
#define CH_EXPRKNOTS     0x00400000     // Expression uses spline knots
#define CH_EXPRMATCH     0x00800000     // Expression has a match() function
#define CH_SYMHARDWIRED  0x01000000     // Variable contains local var ptr
#define CH_EXPRDATA      0x02000000     // Expression sets a data interest
#define CH_EXPRVALUE     (CH_EXPRIVALUE | CH_EXPROVALUE)

// Flags above 0x00008000 are reserved for the channel library
// Flags above 0x02000000 are reserved by the expression library
//      Applications may use any flags between 0x0001 and 0x4000
//      for their own custom flags

//
// It is possible to define constants for the user to use.  For each
//      define, there is a name for the label and a corresponding value.
//      for example:  "XMIN", 0.  This would allow the user to type
//      XMIN instead of having to remember that XMIN is always 0.

class CH_API CH_ExprDefine {
public:
    const char  *label;
    float        value;
};

class CH_SegmentValues;
class CH_Segment;
class CH_Cubic;

class CH_API CH_Bezier
{
public:
    float       x[4];
    float       y[4];

    CH_Bezier() {}

    CH_Bezier( CH_SegmentValues const& sv ) { init( sv ); }

    CH_Bezier( CH_Segment const& seg );

    void        init( CH_SegmentValues const& sv );

    void        getValues( CH_SegmentValues &v );

    static void getCubicFromCVs( float x[4], CH_Cubic &c );

    static void splitInternal( float t, float xin[4],
                                    float xout1[4], float xout2[4] );

    void        splitP( float u, CH_Bezier &a, CH_Bezier &b );

    void        split( float t, CH_Bezier &a, CH_Bezier &b );

    void        splitAndFindSlopeLengths( float t,
                    float &left_in, float &left_out,
                    float &right_in, float &right_out );

    float       timeToParametric( float t );

    float       evalP( float u );

    float       eval( float t );        // t is local

    void        display();
};

class CH_API CH_Cubic
{
public:
    float       t0, t1;
    float       x0, x1, x2, x3;

    float       timeToParametric( float t );    // t -> u

    float       reverseEvalP( float y );        // y -> u

    float       evalP( float u )                // u -> y
    {
        return x0 + u*(x1 + u*(x2 + u*x3));
    }

    float       eval( float t );                // t -> y

    float       calculateSlopeP( float u );

    float       calculateAccelP( float u );

    void        display();
};

#endif

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