ceph/src/boost/libs/qvm/doc/Swizzling.html

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  14 <h1>QVM: Quaternions, Vectors, Matrices</h1>
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  16 <!-- Copyright (c) 2008-2016 Emil Dotchevski and Reverge Studios, Inc. -->
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  19 <div class="RenoIncludeDIV"><div class="RenoAutoDIV"><h3>Swizzling</h3>
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  21 <p>Boost QVM allows <span class="RenoLink"><a href="accessing_vector_elements_and_swizzling_reference.html">accessing vector elements by swizzling</a></span>, exposing vector views of different dimensions, and/or views with reordered elements. The example below rotates <i>v</i> around the X axis, and stores the resulting vector back in <i>v</i> but with the X and Y elements swapped:</p>
  22 <pre>float3 v = {0,0,7};
  23 <span class="RenoLink"><a href="accessing_vector_elements_and_swizzling_reference.html">YXZ</a></span>(v) = <span class="RenoLink"><a href="rotx_mat_scalar_.html">rotx_mat</a></span>&lt;3&gt;(3.14159f) <span class="RenoLink"><a href="operator_times_mat_vec_.html">*</a></span> v;</pre>
  24 <p>A special case of swizzling provides next-dimension-view of a vector object, adding either 0 or 1 as its last component. Assuming <i>float3</i> is a 3D vector type, and <i>float4</i> is a 4D vector type, the following statements are valid:</p>
  25 <pre>float3 v = {0,0,7};
  26 float4 point = <span class="RenoLink"><a href="accessing_vector_elements_and_swizzling_reference.html">XYZ1</a></span>(v); //{0,0,7,1}
  27 float4 vector = <span class="RenoLink"><a href="accessing_vector_elements_and_swizzling_reference.html">XYZ0</a></span>(v); //{0,0,7,0}</pre>
  28 <p>It is also valid for swizzling to address vector elements more than once:</p>
  29 <pre>float3 v = {0,0,7};
  30 float4 v1 = <span class="RenoLink"><a href="accessing_vector_elements_and_swizzling_reference.html">ZZZZ</a></span>(v); //{7,7,7,7}</pre>
  31 <p>Boost QVM defines all permutations of <i>X</i>, <i>Y</i>, <i>Z</i>, <i>W</i> for 1D, 2D, 3D and 4D swizzling, plus each dimension defines variants with <i>0</i> or <i>1</i> used at any position (if 0 or 1 appear at the first position, the swizzling function name begins with underscore, e.g. <i>_1XY</i>).</p>
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  33 <p><b>Tutorial navigation:</b> <span class="RenoLink"><a href="quaternions_vectors_matrices.html">Quaternions, Vectors, Matrices</a></span> | <span class="RenoLink"><a href="c_arrays.html">C Arrays</a></span> | <span class="RenoLink"><a href="Views.html">Views</a></span> | <span class="RenoLink">Swizzling</span> | <span class="RenoLink"><a href="Interoperability.html">Interoperability</a></span><span class="RenoBR">&nbsp;</span><br/><span class="RenoBR">&nbsp;</span><br/>See also: <span class="RenoLink"><a href="index.html">Boost QVM</a></span></p>
  34 </div><!-- Copyright (c) 2008-2016 Emil Dotchevski and Reverge Studios, Inc. -->
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