00001 // Filename: lerp_helpers.h 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 #ifndef LERP_HELPERS_H 00016 #define LERP_HELPERS_H 00017 00018 #include "directbase.h" 00019 00020 // 00021 // The functions defined here include some trivial template functions 00022 // for handling basic lerp computations, common to several .cxx files 00023 // here. 00024 // 00025 00026 //////////////////////////////////////////////////////////////////// 00027 // Function: lerp_value 00028 // Description: Applies the linear lerp computation for a single 00029 // parameter. 00030 //////////////////////////////////////////////////////////////////// 00031 template<class NumericType> 00032 INLINE void 00033 lerp_value(NumericType ¤t_value, 00034 double d, 00035 const NumericType &starting_value, 00036 const NumericType &ending_value) { 00037 current_value = starting_value + d * (ending_value - starting_value); 00038 } 00039 00040 //////////////////////////////////////////////////////////////////// 00041 // Function: lerp_value_from_prev 00042 // Description: Applies the linear lerp computation for a single 00043 // parameter, when the starting value is implicit. 00044 // 00045 // This computes the new value based on assuming the 00046 // prev_value represents the value computed at delta 00047 // prev_d. 00048 //////////////////////////////////////////////////////////////////// 00049 template<class NumericType> 00050 INLINE void 00051 lerp_value_from_prev(NumericType ¤t_value, 00052 double d, double prev_d, 00053 const NumericType &prev_value, 00054 const NumericType &ending_value) { 00055 if (prev_d == 1.0) { 00056 current_value = ending_value; 00057 } else { 00058 NumericType starting_value = 00059 (prev_value - prev_d * ending_value) / (1.0 - prev_d); 00060 current_value = starting_value + d * (ending_value - starting_value); 00061 } 00062 } 00063 00064 00065 #endif 00066