tcbspline.cpp

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/*
**  Command & Conquer Generals Zero Hour(tm)
**  Copyright 2025 Electronic Arts Inc.
**
**  This program is free software: you can redistribute it and/or modify
**  it under the terms of the GNU General Public License as published by
**  the Free Software Foundation, either version 3 of the License, or
**  (at your option) any later version.
**
**  This program is distributed in the hope that it will be useful,
**  but WITHOUT ANY WARRANTY; without even the implied warranty of
**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
**  GNU General Public License for more details.
**
**  You should have received a copy of the GNU General Public License
**  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
 
/***********************************************************************************************
 ***              C O N F I D E N T I A L  ---  W E S T W O O D  S T U D I O S               ***
 ***********************************************************************************************
 *                                                                                             *
 *                 Project Name : WWMath                                                       *
 *                                                                                             *
 *                     $Archive:: /VSS_Sync/wwmath/tcbspline.cpp                              $*
 *                                                                                             *
 *                       Author:: Greg Hjelstrom                                               *
 *                                                                                             *
 *                     $Modtime:: 6/13/01 2:18p                                               $*
 *                                                                                             *
 *                    $Revision:: 6                                                           $*
 *                                                                                             *
 *---------------------------------------------------------------------------------------------*
 * Functions:                                                                                  *
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
 
#include "tcbspline.h"
#include "wwdebug.h"
#include "persistfactory.h"
#include "wwmathids.h"
#include "wwhack.h"
 
 
/*
** Force-Link this module because the linker can't detect that we actually need it...
*/
DECLARE_FORCE_LINK(tcbspline);
 
/*
** Save-Load stuff
*/
SimplePersistFactoryClass<TCBSpline3DClass,WWMATH_CHUNKID_TCBSPLINE3D>    _TCBSpline3DFactory;
 
enum 
{
    // ID's used by TCBSpline3D
    TCB3D_CHUNK_HERMITE3D                  = 0x02071009,   
    TCB3D_CHUNK_PARAMS,           
};
 
 
/*
** TCBSpline3DClass Implemenation
*/
 
int TCBSpline3DClass::Add_Key(const Vector3 & point,float t)
{
    int index;
    index = HermiteSpline3DClass::Add_Key(point,t);
 
    TCBClass params;
    params.Tension = 0.0f;
    params.Continuity = 0.0f;
    params.Bias = 0.0f;
    Params.Insert(index,params);
    return index;
}
 
void TCBSpline3DClass::Remove_Key(int i)
{
    HermiteSpline3DClass::Remove_Key(i);
    Params.Delete(i);
}
 
void TCBSpline3DClass::Clear_Keys(void)
{
    HermiteSpline3DClass::Clear_Keys();
    Params.Clear();
}
 
void TCBSpline3DClass::Set_TCB_Params(int i,float tension,float continuity,float bias)
{
    WWASSERT(i >= 0);
    WWASSERT(i < Params.Count());
    Params[i].Tension = tension;
    Params[i].Continuity = continuity;
    Params[i].Bias = bias;
    TangentsDirty = true;
}
 
void TCBSpline3DClass::Get_TCB_Params(int i,float *tension,float *continuity,float *bias)
{
    if (tension) *tension = Params[i].Tension;
    if (continuity) *continuity = Params[i].Continuity;
    if (bias) *bias = Params[i].Bias;
}
 
void TCBSpline3DClass::Update_Tangents(void)
{
    if (Keys.Count() < 2) {
        for (int i=0; i<Keys.Count(); i++) {
            Tangents[0].InTangent.Set(0,0,0);
            Tangents[0].OutTangent.Set(0,0,0);
        }
    }
 
    // First and Last Key: 
    // Only need to compute the OutTangent for key[0] and the InTangent for key[end]
    int end = Keys.Count() - 1;
    Tangents[0].InTangent.Set(0,0,0);
    Tangents[end].OutTangent.Set(0,0,0);
 
    if (IsLooping) {
 
        // This really only works if the start and end points have the same position...
        // Also just using the TCB params from p0 for both
        float k0 = 0.5f * ((1-Params[0].Tension) * (1-Params[0].Continuity) * (1-Params[0].Bias));
        float k1 = 0.5f * ((1-Params[0].Tension) * (1+Params[0].Continuity) * (1+Params[0].Bias));
        float k2 = 0.5f * ((1-Params[0].Tension) * (1+Params[0].Continuity) * (1-Params[0].Bias));
        float k3 = 0.5f * ((1-Params[0].Tension) * (1-Params[0].Continuity) * (1+Params[0].Bias));
 
        Vector3 dp_in;
        Vector3 dp_out;
        Vector3::Subtract(Keys[0].Point,Keys[end-1].Point,&dp_in);
        Vector3::Subtract(Keys[1].Point,Keys[0].Point,&dp_out);
 
        Vector3::Add(k0*dp_in, k1*dp_out, &Tangents[end].InTangent);
        Vector3::Add(k2*dp_out, k3*dp_in, &Tangents[0].OutTangent);
        
    } else {
        
        float k2 = 0.25f * ((1-Params[0].Tension) * (1+Params[0].Continuity) * (1-Params[0].Bias));
        float k3 = 0.25f * ((1-Params[0].Tension) * (1-Params[0].Continuity) * (1+Params[0].Bias));
 
        Vector3 dp_in;
        Vector3 dp_out;
        Vector3::Subtract(Keys[1].Point,Keys[0].Point,&dp_out);
        dp_in = dp_out;
        Vector3::Add(k2*dp_out, k3*dp_in, &Tangents[0].OutTangent);
 
        float k0 = 0.25f * ((1-Params[0].Tension) * (1-Params[0].Continuity) * (1-Params[0].Bias));
        float k1 = 0.25f * ((1-Params[0].Tension) * (1+Params[0].Continuity) * (1+Params[0].Bias));
        Vector3::Subtract(Keys[end].Point,Keys[end-1].Point,&dp_in);
        dp_out = dp_in;
        Vector3::Add(k0*dp_out, k1*dp_in, &Tangents[end].InTangent);
    }
 
    float total_time = (Keys[1].Time - Keys[0].Time) + (Keys[end].Time - Keys[end-1].Time);
    float in_factor = 2.0f * (Keys[end].Time - Keys[end-1].Time) / total_time;
    float out_factor = 2.0f * (Keys[1].Time - Keys[0].Time) / total_time;
    Tangents[end].InTangent *= in_factor;
    Tangents[0].OutTangent *= out_factor;
 
 
    // Now compute the tangents of all of the normal keys...
    for (int pi=1;pi<Keys.Count() - 1; pi++) {
 
        float k0 = 0.5f * ((1-Params[pi].Tension) * (1-Params[pi].Continuity) * (1-Params[pi].Bias));
        float k1 = 0.5f * ((1-Params[pi].Tension) * (1+Params[pi].Continuity) * (1+Params[pi].Bias));
        float k2 = 0.5f * ((1-Params[pi].Tension) * (1+Params[pi].Continuity) * (1-Params[pi].Bias));
        float k3 = 0.5f * ((1-Params[pi].Tension) * (1-Params[pi].Continuity) * (1+Params[pi].Bias));
 
        Vector3 dp_in;
        Vector3 dp_out;
        Vector3::Subtract(Keys[pi].Point,Keys[pi-1].Point,&dp_in);
        Vector3::Subtract(Keys[pi+1].Point,Keys[pi].Point,&dp_out);
 
        Vector3::Add(k0*dp_out, k1*dp_in, &Tangents[pi].InTangent);
        Vector3::Add(k2*dp_out, k3*dp_in, &Tangents[pi].OutTangent);
 
        float total_time = (Keys[pi+1].Time - Keys[pi-1].Time);
        float in_factor = 2.0f * (Keys[pi].Time - Keys[pi-1].Time) / total_time;
        float out_factor = 2.0f * (Keys[pi+1].Time - Keys[pi].Time) / total_time;
 
        Tangents[pi].InTangent *= in_factor;        // compensating for un-even keys
        Tangents[pi].OutTangent *= out_factor;
 
    }
    TangentsDirty = false;
}
 
const PersistFactoryClass & TCBSpline3DClass::Get_Factory(void) const
{
    return _TCBSpline3DFactory;
}
 
bool TCBSpline3DClass::Save(ChunkSaveClass &csave)
{
    csave.Begin_Chunk(TCB3D_CHUNK_HERMITE3D);
    HermiteSpline3DClass::Save(csave);
    csave.End_Chunk();
    
    csave.Begin_Chunk(TCB3D_CHUNK_PARAMS);
    for (int i=0; i<Params.Count(); i++) {
        csave.Write(&(Params[i].Tension),sizeof(Params[i].Tension));
        csave.Write(&(Params[i].Continuity),sizeof(Params[i].Continuity));
        csave.Write(&(Params[i].Bias),sizeof(Params[i].Bias));
    }
    csave.End_Chunk();
    return true;
}
 
bool TCBSpline3DClass::Load(ChunkLoadClass &cload)
{
    int i;
    TCBClass param;
 
    // reset the keys
    Params.Delete_All();
 
    // read in the chunks
    while (cload.Open_Chunk()) {
        
        switch(cload.Cur_Chunk_ID()) 
        {
            case TCB3D_CHUNK_HERMITE3D:
                HermiteSpline3DClass::Load(cload);
                break;
 
            case TCB3D_CHUNK_PARAMS:
                for (i=0; i<Keys.Count(); i++) {
                    cload.Read(&(param.Tension),sizeof(param.Tension));
                    cload.Read(&(param.Continuity),sizeof(param.Continuity));
                    cload.Read(&(param.Bias),sizeof(param.Bias));
                    Params.Add(param);
                }
                break;
 
            default:
                WWDEBUG_SAY(("Unhandled Chunk: 0x%X File: %s Line: %d\r\n",__FILE__,__LINE__));
                break;
        }
        cload.Close_Chunk();
    }
 
    return true;
}