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Graphics Programming Black Book (Special Edition)
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chapter53
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xsharp15.exe
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APPROT.C
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1991-12-26
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94 lines
/* Routines to perform incremental rotations around the three axes. */
#include <math.h>
#include "polygon.h"
/* Concatenate a rotation by Angle around the X axis to the
transformation in XformToChange, placing the result back into
XformToChange. */
void AppendRotationX(Xform XformToChange, TAngle Angle)
{
Fixedpoint CosTemp, SinTemp;
Fixedpoint Temp10, Temp11, Temp12, Temp20, Temp21, Temp22;
/* Get the sine and cosine of the rotation angle */
CosSin(Angle, &CosTemp, &SinTemp);
/* Calculate the new values of the six affected matrix entries */
Temp10 = FixedMul(CosTemp, XformToChange[1][0]) +
FixedMul(-SinTemp, XformToChange[2][0]);
Temp11 = FixedMul(CosTemp, XformToChange[1][1]) +
FixedMul(-SinTemp, XformToChange[2][1]);
Temp12 = FixedMul(CosTemp, XformToChange[1][2]) +
FixedMul(-SinTemp, XformToChange[2][2]);
Temp20 = FixedMul(SinTemp, XformToChange[1][0]) +
FixedMul(CosTemp, XformToChange[2][0]);
Temp21 = FixedMul(SinTemp, XformToChange[1][1]) +
FixedMul(CosTemp, XformToChange[2][1]);
Temp22 = FixedMul(SinTemp, XformToChange[1][2]) +
FixedMul(CosTemp, XformToChange[2][2]);
/* Put the results back into XformToChange */
XformToChange[1][0] = Temp10; XformToChange[1][1] = Temp11;
XformToChange[1][2] = Temp12; XformToChange[2][0] = Temp20;
XformToChange[2][1] = Temp21; XformToChange[2][2] = Temp22;
}
/* Concatenate a rotation by Angle around the Y axis to the
transformation in XformToChange, placing the result back into
XformToChange. */
void AppendRotationY(Xform XformToChange, TAngle Angle)
{
Fixedpoint CosTemp, SinTemp;
Fixedpoint Temp00, Temp01, Temp02, Temp20, Temp21, Temp22;
/* Get the sine and cosine of the rotation angle */
CosSin(Angle, &CosTemp, &SinTemp);
/* Calculate the new values of the six affected matrix entries */
Temp00 = FixedMul(CosTemp, XformToChange[0][0]) +
FixedMul(SinTemp, XformToChange[2][0]);
Temp01 = FixedMul(CosTemp, XformToChange[0][1]) +
FixedMul(SinTemp, XformToChange[2][1]);
Temp02 = FixedMul(CosTemp, XformToChange[0][2]) +
FixedMul(SinTemp, XformToChange[2][2]);
Temp20 = FixedMul(-SinTemp, XformToChange[0][0]) +
FixedMul( CosTemp, XformToChange[2][0]);
Temp21 = FixedMul(-SinTemp, XformToChange[0][1]) +
FixedMul(CosTemp, XformToChange[2][1]);
Temp22 = FixedMul(-SinTemp, XformToChange[0][2]) +
FixedMul(CosTemp, XformToChange[2][2]);
/* Put the results back into XformToChange */
XformToChange[0][0] = Temp00; XformToChange[0][1] = Temp01;
XformToChange[0][2] = Temp02; XformToChange[2][0] = Temp20;
XformToChange[2][1] = Temp21; XformToChange[2][2] = Temp22;
}
/* Concatenate a rotation by Angle around the Z axis to the
transformation in XformToChange, placing the result back into
XformToChange. */
void AppendRotationZ(Xform XformToChange, TAngle Angle)
{
Fixedpoint CosTemp, SinTemp;
Fixedpoint Temp00, Temp01, Temp02, Temp10, Temp11, Temp12;
/* Get the sine and cosine of the rotation angle */
CosSin(Angle, &CosTemp, &SinTemp);
/* Calculate the new values of the six affected matrix entries */
Temp00 = FixedMul(CosTemp, XformToChange[0][0]) +
FixedMul(-SinTemp, XformToChange[1][0]);
Temp01 = FixedMul(CosTemp, XformToChange[0][1]) +
FixedMul(-SinTemp, XformToChange[1][1]);
Temp02 = FixedMul(CosTemp, XformToChange[0][2]) +
FixedMul(-SinTemp, XformToChange[1][2]);
Temp10 = FixedMul(SinTemp, XformToChange[0][0]) +
FixedMul(CosTemp, XformToChange[1][0]);
Temp11 = FixedMul(SinTemp, XformToChange[0][1]) +
FixedMul(CosTemp, XformToChange[1][1]);
Temp12 = FixedMul(SinTemp, XformToChange[0][2]) +
FixedMul(CosTemp, XformToChange[1][2]);
/* Put the results back into XformToChange */
XformToChange[0][0] = Temp00; XformToChange[0][1] = Temp01;
XformToChange[0][2] = Temp02; XformToChange[1][0] = Temp10;
XformToChange[1][1] = Temp11; XformToChange[1][2] = Temp12;
}