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[openvrml-commit] openvrml/src/libopenvrml-gl/openvrml/gl viewer.cpp, 1.56, 1.57
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From: Braden M. <br...@us...> - 2007-01-21 18:05:46
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Update of /cvsroot/openvrml/openvrml/src/libopenvrml-gl/openvrml/gl In directory sc8-pr-cvs3.sourceforge.net:/tmp/cvs-serv3857/src/libopenvrml-gl/openvrml/gl Modified Files: viewer.cpp Log Message: Improved comments. Index: viewer.cpp =================================================================== RCS file: /cvsroot/openvrml/openvrml/src/libopenvrml-gl/openvrml/gl/viewer.cpp,v retrieving revision 1.56 retrieving revision 1.57 diff -C2 -d -r1.56 -r1.57 *** viewer.cpp 16 Jan 2007 08:44:22 -0000 1.56 --- viewer.cpp 21 Jan 2007 18:05:44 -0000 1.57 *************** *** 2152,2156 **** } ! OPENVRML_LOCAL float get_spine_length(const std::vector<openvrml::vec3f> & spine) { --- 2152,2171 ---- } ! /** ! * @brief Get the length of an Extrusion spine. ! * ! * The length of the spine is used in computing texture coordinates for an ! * Extrusion. In order to determine the texture coordinates at a given ! * point on the Extrusion cross-section, the distance from the start of ! * the spine is divided by its total length. As such, this function ! * returns 1.0 if the length of the spine is 0 (to avoid dividing by ! * zero). ! * ! * @param[in] spine Extrusion spine. ! * ! * @return the length of the Extrusion spine described by @p spine; or 1.0 ! * if the length is 0. ! */ ! OPENVRML_GL_LOCAL float get_spine_length(const std::vector<openvrml::vec3f> & spine) { *************** *** 2167,2173 **** } ! OPENVRML_LOCAL float ! get_cross_section_length(const std::vector<openvrml::vec2f> & cross_section) { using std::vector; --- 2182,2204 ---- } ! /** ! * @brief Get the length of an Extrusion cross-section. ! * ! * The length of the cross-section is used in computing texture ! * coordinates for an Extrusion. In order to determine the texture ! * coordinates at a given point on the Extrusion cross-section, the ! * distance from the start of the cross-section is divided by its total ! * length. As such, this function returns 1.0 if the length of the ! * cross-section is 0 (to avoid dividing by zero). ! * ! * @param[in] cross_section Extrusion cross-section. ! * ! * @return the length of the Extrusion cross-section described by ! * @p cross_section; or 1.0 if the length is 0. ! */ ! OPENVRML_GL_LOCAL float ! get_cross_section_length( ! const std::vector<openvrml::vec2f> & cross_section) { using std::vector; *************** *** 2296,2302 **** * @brief Determine if the extrusion spine points are collinear. * ! * Incidentally this function determines the axes for the initial ! * spine-aligned cross-section plane (which are consistent for the extent ! * of the extrusion if the spine points are collinear). * * @param[in] spine the extrusion spine. --- 2327,2333 ---- * @brief Determine if the extrusion spine points are collinear. * ! * If this function returns @c true, @p scp_x, @p scp_y, and @p scp_z are ! * the axes of the spine-aligned cross-section plane that should be used ! * for the extent of the extrusion. * * @param[in] spine the extrusion spine. *************** *** 2327,2335 **** using openvrml::make_vec3f; static const vec3f zero = make_vec3f(); - scp_y = zero; scp_z = zero; - vec3f prev_scp_y = zero, prev_scp_z = zero; for (vector<vec3f>::const_iterator point = spine.begin(); --- 2358,2372 ---- using openvrml::make_vec3f; + // + // First, iterate over the spine points until either the y- or z-axis + // for the spine-aligned cross-section plane (SCP) is valid (i.e., + // nonzero). We bail out of the loop as soon as we get a valid y- or + // z-axis; because that means we've hit the first noncollinear point. + // If the points are all collinear, we won't have a valid z-axis (or + // y-axis) when we're done. + // static const vec3f zero = make_vec3f(); scp_y = zero; scp_z = zero; vec3f prev_scp_y = zero, prev_scp_z = zero; for (vector<vec3f>::const_iterator point = spine.begin(); *************** *** 2337,2346 **** ++point) { if (prev_scp_y == zero) { ! scp_y = compute_scp_y_axis(point, spine.begin(), spine.end() - 1, prev_scp_y); if (scp_y != zero) { prev_scp_y = scp_y; } } if (prev_scp_z == zero) { ! scp_z = compute_scp_z_axis(point, spine.begin(), spine.end() - 1, prev_scp_z); if (scp_z != zero) { prev_scp_z = scp_z; } --- 2374,2387 ---- ++point) { if (prev_scp_y == zero) { ! scp_y = compute_scp_y_axis(point, ! spine.begin(), ! spine.end() - 1, prev_scp_y); if (scp_y != zero) { prev_scp_y = scp_y; } } if (prev_scp_z == zero) { ! scp_z = compute_scp_z_axis(point, ! spine.begin(), ! spine.end() - 1, prev_scp_z); if (scp_z != zero) { prev_scp_z = scp_z; } *************** *** 2348,2355 **** } ! bool spine_points_collinear = false; ! if (prev_scp_y == zero) { prev_scp_y = make_vec3f(0.0, 1.0, 0.0); } if (prev_scp_z == zero) { prev_scp_z = make_vec3f(0.0, 0.0, 1.0); if (prev_scp_y != make_vec3f(0.0, 1.0, 0.0)) { --- 2389,2410 ---- } ! // ! // If all the points are coincident, prev_scp_y will be invalid ! // (zero). Set it to (0 1 0). ! // if (prev_scp_y == zero) { prev_scp_y = make_vec3f(0.0, 1.0, 0.0); } + + // + // If all the points are collinear, prev_scp_z will be invalid (zero). + // Default it to (0 0 1); then, per 6.18.3 of VRML97: + // + // If the entire spine is collinear, the SCP is computed by finding + // the rotation of a vector along the positive Y-axis (v1) to the + // vector formed by the spine points (v2). The Y=0 plane is then + // rotated by this value. + // + bool spine_points_collinear = false; if (prev_scp_z == zero) { + spine_points_collinear = true; prev_scp_z = make_vec3f(0.0, 0.0, 1.0); if (prev_scp_y != make_vec3f(0.0, 1.0, 0.0)) { *************** *** 2360,2364 **** prev_scp_z *= rot_mat; } - spine_points_collinear = true; } --- 2415,2418 ---- |
