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gusso

matrix rotate and transform vectors.

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I need help regarding the following piece of code:
CMatrix mat;
mat.Rotate( Angle / (float)M_PI * 180.0f );
mat.TransformVectors( vectors, 1 );
I'd like to understand what TransformVectors actually does, is there any code example I can take a look at?, perhaps a matrix library?. I wrote my own implementation out of the blue and it's giving incorrect results, that's why I'm puzzled about this. Thanks

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It looks like they're storing a rotation in the matrix and then transforming the vector by that matrix (by multiplying the vector by the matrix).

This is code in a project of mine which does essentially the same thing. Think of it as the vector being transformed by the matrix (instead of the other way around).


// Gets the matrix transformation.
gfx::m4r<GLfloat> trans;
glGetFloatv(GL_MODELVIEW_MATRIX, *trans);

gfx::v4r<GLfloat> vertex_normal(
normal_array,
normal_array[i+1],
normal_array[i+2],
0);
vertex_normal.rotate(trans); // Rotates the vector using the matrix.
// Essentially vertex_normal = vertex_normal * rotation_part_of_transform_matrix




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I wonder if this is an efficient way of going around this. I've seen it on routines that transform vectors from world to relative and vice versa but I don't think it's anywhere efficient

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