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expression must have arithmetic or unscoped enum type

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[source lang="cpp"]void CalculateTangentArray(long vertexCount, const D3DXVECTOR3 *vertex, const D3DXVECTOR3 *normal,
const D3DXVECTOR2 *texcoord, long triangleCount, const Triangle *triangle, D3DXVECTOR3 *tangent)
D3DXVECTOR3 *tan1 = new D3DXVECTOR3[vertexCount * 2];
D3DXVECTOR3 *tan2 = tan1 + vertexCount;
ZeroMemory(tan1, vertexCount * sizeof(D3DXVECTOR3) * 2);

for (long a = 0; a < triangleCount; a++)
long i1 = triangle->index[0];
long i2 = triangle->index[1];
long i3 = triangle->index[2];

const D3DXVECTOR3& v1 = vertex[i1];
const D3DXVECTOR3& v2 = vertex[i2];
const D3DXVECTOR3& v3 = vertex[i3];

const D3DXVECTOR2& w1 = texcoord[i1];
const D3DXVECTOR2& w2 = texcoord[i2];
const D3DXVECTOR2& w3 = texcoord[i3];

float x1 = v2.x - v1.x;
float x2 = v3.x - v1.x;
float y1 = v2.y - v1.y;
float y2 = v3.y - v1.y;
float z1 = v2.z - v1.z;
float z2 = v3.z - v1.z;

float s1 = w2.x - w1.x;
float s2 = w3.x - w1.x;
float t1 = w2.y - w1.y;
float t2 = w3.y - w1.y;

float r = 1.0F / (s1 * t2 - s2 * t1);
D3DXVECTOR3 sdir((t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r,
(t2 * z1 - t1 * z2) * r);
D3DXVECTOR3 tdir((s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r,
(s1 * z2 - s2 * z1) * r);

tan1[i1] += sdir;
tan1[i2] += sdir;
tan1[i3] += sdir;

tan2[i1] += tdir;
tan2[i2] += tdir;
tan2[i3] += tdir;


for (long a = 0; a < vertexCount; a++)
const D3DXVECTOR3* n = &normal[a];
const D3DXVECTOR3* t = &tan1[a];

// Gram-Schmidt orthogonalize

tangent[a] = (t - n * D3DXVec3Dot(n, t)).Normalize();


delete[] tan1;

The above function computes a 3d tangent vector.The problem is on this line:
tangent[a] = (t - n * D3DXVec3Dot(n, t)).Normalize();

The following error appears under 'n': const D3DXVECTOR3* n expression must have arithmetic or unscoped enum type

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const D3DXVECTOR3* n = &normal[a];
tangent[a] = (t - n * D3DXVec3Dot(n, t)).Normalize();

Your n is pointer; you cannot multiply pointer by float.

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Both t and n are pointers to D3DXVECTOR3 so you must dereference them to be able to do the subtraction.

Where did you get the code from? I'm personaly quite confused about the second part of the line. The D3DXVECTOR3 doesn't have any Normalize() method, does it?

I'd say the following should work:

tangent[a] = *t - *n * D3DXVec3Dot(n, t);
D3DXVec3Normalize(&tangent[a], &tangent[a]);

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