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add comments on Compare_angle_3

This commit is contained in:
Laurent Rineau 2024-01-16 15:08:25 +01:00
parent 4a8693b972
commit 00b4f722e8
1 changed files with 6 additions and 2 deletions
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8
Kernel_23/include/CGAL/Kernel/function_objects.h
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@ -216,9 +216,13 @@ namespace CommonKernelFunctors {
const Vector_3 bc2 = c2 - b2; const Vector_3 bc2 = c2 - b2;
const FT sc_prod_1 = ba1 * bc1; const FT sc_prod_1 = ba1 * bc1;
const FT sc_prod_2 = ba2 * bc2; const FT sc_prod_2 = ba2 * bc2;
// Reminder: cos(angle) = scalar_product(ba, bc) / (length(ba)*length(bc))
// cosine is decreasing on 0, pi
// thus angle1 < angle2 is equivalent to cos(angle1) > cos(angle2)
if(sc_prod_1 >= 0) { if(sc_prod_1 >= 0) {
if(sc_prod_2 >= 0) { if(sc_prod_2 >= 0) {
// the two cosine are >= 0, cosine is decreasing on [0,1] // the two cosine are >= 0, we can compare the squares
// (square(x) is increasing when x>=0
return CGAL::compare(CGAL::square(sc_prod_2)* return CGAL::compare(CGAL::square(sc_prod_2)*
ba1.squared_length()*bc1.squared_length(), ba1.squared_length()*bc1.squared_length(),
CGAL::square(sc_prod_1)* CGAL::square(sc_prod_1)*
@ -228,7 +232,7 @@ namespace CommonKernelFunctors {
} }
} else { } else {
if(sc_prod_2 < 0) { if(sc_prod_2 < 0) {
// the two cosine are < 0, cosine is increasing on [-1,0] // the two cosine are < 0, square(x) is decreasing when x<0
return CGAL::compare(CGAL::square(sc_prod_1)* return CGAL::compare(CGAL::square(sc_prod_1)*
ba2.squared_length()*bc2.squared_length(), ba2.squared_length()*bc2.squared_length(),
CGAL::square(sc_prod_2)* CGAL::square(sc_prod_2)*