07-13-2003, 06:31 AM

i'm trying to multiply a vector by a matrix the problem is that doesn't

perform any rotation on the vector !

argh... i'm blocked in the creation of my little 3d game ( Space invader 2003)

i've this formula to multiply a vector by a matrix

| A B C D | | x1 x2 x3 x4 x5 | | A.x1+B.y1+C.z1+D A.x2+B.y2+C.z2+D ... |

| E F G H | . | y1 y2 y3 y4 y5 | = | E.x1+F.y1+G.z1+H E.x2+F.y2+G.z2+H ... |

| I J K L | | z1 z2 y3 y4 z5 | | I.x1+J.y1+K.z1+L I.x2+J.y2+K.z2+L ... |

| M N O P | | 1 1 1 1 1 | | M.x1+N.y1+O.z1+P M.x2+N.y2+O.z2+P ... |

so i've created this func

void M4x4multV3(Vector3f *result,Vector3f *in,float *m)

{

result->x=(m[0]*in->x)+(m[4]*in->y)+(m[8]*in->z)+m[12];

result->y=(m[1]*in->x)+(m[5]*in->y)+(m[9]*in->z)+m[13];

result->z=(m[2]*in->x)+(m[6]*in->y)+(m[10]*in->z)+m[14];

}

/*

m is a 4x4 matrix OpenGL order

Vector3f is define like this

typedef struct

{

float x,y,z;

}Vector3f;

*/

perform any rotation on the vector !

argh... i'm blocked in the creation of my little 3d game ( Space invader 2003)

i've this formula to multiply a vector by a matrix

| A B C D | | x1 x2 x3 x4 x5 | | A.x1+B.y1+C.z1+D A.x2+B.y2+C.z2+D ... |

| E F G H | . | y1 y2 y3 y4 y5 | = | E.x1+F.y1+G.z1+H E.x2+F.y2+G.z2+H ... |

| I J K L | | z1 z2 y3 y4 z5 | | I.x1+J.y1+K.z1+L I.x2+J.y2+K.z2+L ... |

| M N O P | | 1 1 1 1 1 | | M.x1+N.y1+O.z1+P M.x2+N.y2+O.z2+P ... |

so i've created this func

void M4x4multV3(Vector3f *result,Vector3f *in,float *m)

{

result->x=(m[0]*in->x)+(m[4]*in->y)+(m[8]*in->z)+m[12];

result->y=(m[1]*in->x)+(m[5]*in->y)+(m[9]*in->z)+m[13];

result->z=(m[2]*in->x)+(m[6]*in->y)+(m[10]*in->z)+m[14];

}

/*

m is a 4x4 matrix OpenGL order

Vector3f is define like this

typedef struct

{

float x,y,z;

}Vector3f;

*/