Matrix 4x4 Translation of a vector

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Submitted by markos on Sat, 03/01/2008 - 20:56.

(Please see Matrix 4x4 addition/subtraction (floats) for the typedefs and definitions used.)

Getting the translation matrix of a vector is essential to do movements of a vector in 3D space.

For the theory behind translation matrices please see http://en.wikipedia.org/wiki/Translation_(geometry)

We follow a similar method as in the Identity matrix:

void Mat44Identity(Mat44 m, Vec4f pVec)
{
        vector float v0 = vec_ctf(vec_splat_u32(0), 0);
        LOAD_VECTOR(vvec, pVec);
 
        CLEAR_VECTOR(&m[0]);
        CLEAR_VECTOR(&m[4]);
        CLEAR_VECTOR(&m[8]);
        STORE_VECTOR(vvec, &m[12]);
        m[15] = 1.0f;
}

where we defined CLEAR_VECTOR as the macro:

#define CLEAR_VECTOR(vs)                          \
{                                                 \
        vec_st(vec_splat_s8(0), 0, (float *)vs);  \
}

SIMD