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Lib/Include/CML/mathlib/projection.h

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+/* -*- C++ -*- ------------------------------------------------------------
+ 
+Copyright (c) 2007 Jesse Anders and Demian Nave http://cmldev.net/
+
+The Configurable Math Library (CML) is distributed under the terms of the
+Boost Software License, v1.0 (see cml/LICENSE for details).
+
+ *-----------------------------------------------------------------------*/
+/** @file
+ *  @brief
+ */
+
+#ifndef projection_h
+#define projection_h
+
+#include <cml/mathlib/matrix_concat.h>
+#include <cml/mathlib/vector_transform.h>
+
+/* Functions for projection and 'unprojection' of points in 3D. */
+
+namespace cml {
+
+namespace detail {
+
+template < typename E > void
+divide_by_w(vector< E,fixed<4> >& v) {
+    v *= E(1) / v[3];
+}
+
+} // namespace detail
+
+/* Project a point to screen space using the given model, view, projection,
+ * and viewport matrices. The z value of the returned point is a depth value
+ * in the range specified by the viewport matrix.
+ */
+
+template <class MatT_1, class MatT_2, class MatT_3, class MatT_4, class VecT>
+vector< typename VecT::value_type, fixed<3> > project_point(
+    const MatT_1& model,
+    const MatT_2& view,
+    const MatT_3& projection,
+    const MatT_4& viewport,
+    const VecT& p)
+{
+    return project_point(
+        detail::matrix_concat_transforms_4x4(model,view),
+        projection,
+        viewport,
+        p
+    );
+}
+
+/* Project a point to screen space using the given modelview, projection, and
+ * viewport matrices. The z value of the returned point is a depth value in
+ * the range specified by the viewport matrix.
+ */
+
+template < class MatT_1, class MatT_2, class MatT_3, class VecT >
+vector< typename VecT::value_type, fixed<3> > project_point(
+    const MatT_1& modelview,
+    const MatT_2& projection,
+    const MatT_3& viewport,
+    const VecT& p)
+{
+    typedef vector< typename VecT::value_type, fixed<3> > vector3_type;
+    typedef vector< typename VecT::value_type, fixed<4> > vector4_type;
+    typedef typename vector3_type::value_type value_type;
+
+    detail::CheckVec3(p);
+
+    vector4_type result = transform_vector_4D(
+        detail::matrix_concat_transforms_4x4(
+            modelview,
+            detail::matrix_concat_transforms_4x4(
+                projection,
+                viewport
+            )
+        ),
+        vector4_type(p[0],p[1],p[2],value_type(1))
+    );
+    detail::divide_by_w(result);
+    return vector3_type(result[0],result[1],result[2]);
+}
+
+/* 'Unproject' a point from screen space using the given model, view,
+ * projection, and viewport matrices. The z value of the input point is a
+ * depth value in the range specified by the viewport matrix.
+ */
+
+template <class MatT_1, class MatT_2, class MatT_3, class MatT_4, class VecT>
+vector< typename VecT::value_type, fixed<3> > unproject_point(
+    const MatT_1& model,
+    const MatT_2& view,
+    const MatT_3& projection,
+    const MatT_4& viewport,
+    const VecT& p)
+{
+    return unproject_point(
+        detail::matrix_concat_transforms_4x4(model,view),
+        projection,
+        viewport,
+        p
+    );
+}
+
+/* 'Unproject' a point from screen space using the given modelview,
+ * projection, and viewport matrices. The z value of the input point is a
+ * depth value in the range specified by the viewport matrix.
+ */
+ 
+template < class MatT_1, class MatT_2, class MatT_3, class VecT >
+vector< typename VecT::value_type, fixed<3> > unproject_point(
+    const MatT_1& modelview,
+    const MatT_2& projection,
+    const MatT_3& viewport,
+    const VecT& p)
+{
+    typedef vector< typename VecT::value_type, fixed<3> > vector3_type;
+    typedef vector< typename VecT::value_type, fixed<4> > vector4_type;
+    typedef typename vector3_type::value_type value_type;
+
+    detail::CheckVec3(p);
+
+    vector4_type result = transform_vector_4D(
+        inverse(
+            detail::matrix_concat_transforms_4x4(
+                modelview,
+                detail::matrix_concat_transforms_4x4(
+                    projection,
+                    viewport
+                )
+            )
+        ),
+        vector4_type(p[0],p[1],p[2],value_type(1))
+    );
+    detail::divide_by_w(result);
+    return vector3_type(result[0],result[1],result[2]);
+}
+
+} // namespace cml
+
+#endif