ok looks like ife found it…is it here in?

md2ComputeModelInstant(Md2ModelInstant *instant,

int frameA, int frameB, float frameBlendWeight,

Vector objectSpaceLightPosition[],

Vector objectSpaceEyePosition[])

if so, is it that?

```
/* Compute the partial derivatives of X, Y, and Z with respect to S and T. */
{
GLfloat vec0[4], vec1[4]; /* Five components: X, Y, Z, S, T. */
/* Need difference vectors to find cross product. */
vec0[0] = v[1][0] - v[0][0];
vec0[1] = v[1][1] - v[0][1];
vec0[2] = v[1][2] - v[0][2];
vec0[3] = stc[1][0] - stc[0][0];
vec1[0] = v[2][0] - v[0][0];
vec1[1] = v[2][1] - v[0][1];
vec1[2] = v[2][2] - v[0][2];
vec1[3] = stc[2][0] - stc[0][0];
pxpt = (vec0[3] * vec1[0] - vec0[0] * vec1[3]);
pypt = (vec0[3] * vec1[1] - vec0[1] * vec1[3]);
pzpt = (vec0[3] * vec1[2] - vec0[2] * vec1[3]);
invlen = invSqrt(pxpt*pxpt + pypt*pypt + pzpt*pzpt);
pxpt *= invlen;
pypt *= invlen;
pzpt *= invlen;
}
```