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Initial Bresenham line algorithm

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This commit is contained in:
John Wellbelove 2020-08-25 12:47:23 +01:00
parent ae64cfa681
commit 4f20a9e3db
1 changed files with 28 additions and 33 deletions
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61
include/etl/bresenham.h
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@ -41,7 +41,7 @@ namespace etl
{
//***************************************************************************
/// A pseudo-container that generates points on a line, using Bresenham's
/// line algorithm.
/// line algorithm.
//***************************************************************************
template <typename TPoint, typename TIntegral = int>
class bresenham_line
@ -153,22 +153,20 @@ namespace etl
dx = (end_.x < start_.x) ? start_.x - end_.x : end_.x - start_.x;
dy = (end_.y < start_.y) ? start_.y - end_.y : end_.y - start_.y;
major_axis = (dx < dy) ? Axis::Y : Axis::X;
if (major_axis == Axis::X)
{
total_count = dx;
dy *= 2;
balance = dy - dx;
dx *= 2;
}
else
if (is_y_major_axis())
{
total_count = dy;
dx *= 2;
balance = dx - dy;
dy *= 2;
}
else
{
total_count = dx;
dy *= 2;
balance = dy - dx;
dx *= 2;
}
current_count = total_count;
}
@ -230,35 +228,21 @@ namespace etl
private:
//***************************************************
/// The major axis.
/// Returns true if Y is the major axis.
//***************************************************
struct Axis
int is_y_major_axis() const
{
enum
{
X,
Y
};
};
return dx < dy;
}
//***************************************************
/// Calculate the next point.
//***************************************************
void next()
{
if (major_axis == Axis::X)
{
if (do_minor_increment)
{
current.y += y_increment;
balance -= dx;
}
current.x += x_increment;
balance += dy;
}
else
if (is_y_major_axis())
{
// Y major axis.
if (do_minor_increment)
{
current.x += x_increment;
@ -268,6 +252,18 @@ namespace etl
current.y += y_increment;
balance += dx;
}
else
{
// X major axis.
if (do_minor_increment)
{
current.y += y_increment;
balance -= dx;
}
current.x += x_increment;
balance += dy;
}
--current_count;
@ -289,8 +285,7 @@ namespace etl
const TIntegral y_increment;
TIntegral dx;
TIntegral dy;
TIntegral major_axis;
TIntegral count;
TIntegral total_count;
TIntegral current_count;
TIntegral balance;
bool do_minor_increment;