Panda3D
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00001 // Filename: cLerpInterval.cxx 00002 // Created by: drose (27Aug02) 00003 // 00004 //////////////////////////////////////////////////////////////////// 00005 // 00006 // PANDA 3D SOFTWARE 00007 // Copyright (c) Carnegie Mellon University. All rights reserved. 00008 // 00009 // All use of this software is subject to the terms of the revised BSD 00010 // license. You should have received a copy of this license along 00011 // with this source code in a file named "LICENSE." 00012 // 00013 //////////////////////////////////////////////////////////////////// 00014 00015 #include "cLerpInterval.h" 00016 #include "string_utils.h" 00017 00018 TypeHandle CLerpInterval::_type_handle; 00019 00020 //////////////////////////////////////////////////////////////////// 00021 // Function: CLerpInterval::string_blend_type 00022 // Access: Published, Static 00023 // Description: Returns the BlendType enumerated value corresponding 00024 // to the indicated string, or BT_invalid if the string 00025 // doesn't match anything. 00026 //////////////////////////////////////////////////////////////////// 00027 CLerpInterval::BlendType CLerpInterval:: 00028 string_blend_type(const string &blend_type) { 00029 if (blend_type == "easeIn") { 00030 return BT_ease_in; 00031 } else if (blend_type == "easeOut") { 00032 return BT_ease_out; 00033 } else if (blend_type == "easeInOut") { 00034 return BT_ease_in_out; 00035 } else if (blend_type == "noBlend") { 00036 return BT_no_blend; 00037 } else { 00038 return BT_invalid; 00039 } 00040 } 00041 00042 //////////////////////////////////////////////////////////////////// 00043 // Function: CLerpInterval::compute_delta 00044 // Access: Protected 00045 // Description: Given a t value in the range [0, get_duration()], 00046 // returns the corresponding delta value clamped to the 00047 // range [0, 1], after scaling by duration and applying 00048 // the blend type. 00049 //////////////////////////////////////////////////////////////////// 00050 double CLerpInterval:: 00051 compute_delta(double t) const { 00052 double duration = get_duration(); 00053 if (duration == 0.0) { 00054 // If duration is 0, the lerp works as a set. Thus, the delta is 00055 // always 1.0, the terminating value. 00056 return 1.0; 00057 } 00058 t /= duration; 00059 t = min(max(t, 0.0), 1.0); 00060 00061 switch (_blend_type) { 00062 case BT_ease_in: 00063 { 00064 double t2 = t * t; 00065 return ((3.0 * t2) - (t2 * t)) * 0.5; 00066 } 00067 00068 case BT_ease_out: 00069 { 00070 double t2 = t * t; 00071 return ((3.0 * t) - (t2 * t)) * 0.5; 00072 } 00073 00074 case BT_ease_in_out: 00075 { 00076 double t2 = t * t; 00077 return (3.0 * t2) - (2.0 * t * t2); 00078 } 00079 00080 default: 00081 return t; 00082 } 00083 }