void Camera_GetViewMat(Camera *camera)
{
mat4x4 R;
mat4x4_Rot(R, camera->transform.quaternion);
vec3 forward = { 0.0f, 0.0f, -1.0f };
vec3 cam_forward;
mat3x3_MulVec3(cam_forward, R, forward);
vec3 right = { 1.0f, 0.0f, 0.0f };
vec3 cam_right;
mat3x3_MulVec3(cam_right, R, right);
vec3 cam_up;
vec3_CrossProd(cam_up, cam_right, cam_forward);
vec3 target;
vec3_Add(target, cam_forward, camera->transform.position);
vec3 n;
vec3_Sub(n, camera->transform.position, target);
vec3_Norm(n, n);
vec3 u;
vec3_CrossProd(u, cam_up, n);
vec3_Norm(u, u);
vec3 v;
vec3_CrossProd(v, n, u);
int i = 0;
for(i = 0; i < 3; ++i)
camera->view_matrix[0][i] = u[i];
for(i = 0; i < 3; ++i)
camera->view_matrix[1][i] = v[i];
for(i = 0; i < 3; ++i)
camera->view_matrix[2][i] = n[i];
for(i = 0; i < 3; ++i)
camera->view_matrix[3][i] = 0.0f;
vec3_Negate(u, u);
vec3_Negate(v, v);
vec3_Negate(n, n);
camera->view_matrix[0][3] = vec3_DotProd(u, camera->transform.position);
camera->view_matrix[1][3] = vec3_DotProd(v, camera->transform.position);
camera->view_matrix[2][3] = vec3_DotProd(n, camera->transform.position);
camera->view_matrix[3][3] = 1.0f;
}
Matrix4* mat4_LookAtView( const Vector3* eyePos, const Vector3* lookPos, const Vector3* up, Matrix4* out )
{
assert( out != NULL );
Vector3 u, f, s;
memcpy( out, &IDENTITY_MATRIX, sizeof( Matrix4 ) );
vec3_Subtract( lookPos, eyePos, &f );
vec3_Normalize( &f );
memcpy( &u, up, sizeof( Vector3 ) );
vec3_Normalize( &u );
vec3_CrossProd( &f, &u, &s );
vec3_Normalize( &s );
vec3_CrossProd( &s, &f, &u );
out->m[0] = s.v[0];
out->m[4] = s.v[1];
out->m[8] = s.v[2];
out->m[1] = u.v[0];
out->m[5] = u.v[1];
out->m[9] = u.v[2];
out->m[2] = -f.v[0];
out->m[6] = -f.v[1];
out->m[10] = -f.v[2];
out->m[12] = -vec3_DotProd( &s, eyePos );
out->m[13] = -vec3_DotProd( &u, eyePos );
out->m[14] = vec3_DotProd( &f, eyePos );
return out;
}
