Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Avoid wasting cycles on lines that are drawn off-screen. #60

Open
wants to merge 5 commits into
base: master
Choose a base branch
from
Open

Avoid wasting cycles on lines that are drawn off-screen. #60

Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
9829745
Avoid wasting cycles on lines or part of lines that are drawn off-scr…
Jan 27, 2021
20fa686
Fix for previous commit.
Jan 27, 2021
9a66f34
Revert check for partial lines as it modifies the way the line looks
Jan 27, 2021
3042177
For lines that are partially offscreen, don't draw the offscreen dots…
Jan 27, 2021
e6ed27b
Add some much needed comments.
Jan 27, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
65 changes: 65 additions & 0 deletions src/Graphics/Graphics.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -409,11 +409,76 @@ class Graphics: public ImageDrawer

void line(int x1, int y1, int x2, int y2, Color color)
{
// If line is not inside screen bounds, don't draw it
if ( (x1 < 0 && x2 < 0) || (x1 > xres && x2 > xres) ||
(y1 < 0 && y2 < 0) || (y1 > yres && y2 > yres) )
return;

int x, y, xe, ye;
int dx = x2 - x1;
int dy = y2 - y1;
int dx1 = labs(dx);
int dy1 = labs(dy);

float dxo = dx;
float dyo = dy;
// Recalculate a coordinate for x1 that is inside the screen bounds
if (x1 < 0 || x1 > xres)
{
// Set the new x1 to be at the edge of the screen
x1 = (x1 < 0) ? 0 : xres;
// Recalculate the distance on x axis
dx = x2 - x1;
dx1 = labs(dx);
// Calculate the new y1 based on the new position of x1
y1 = y2 - dy * dx / dxo;
// Recalculate the distance on y axis
dyo = dy = y2 - y1;
dy1 = labs(dy);
}
// Recalculate a coordinate for x2 that is inside the screen bounds
if (x2 < 0 || x2 > xres)
{
// Set the new x2 to be at the edge of the screen
x2 = (x2 < 0) ? 0 : xres;
// Recalculate the distance on x axis
dx = x2 - x1;
dx1 = labs(dx);
// Calculate the new y2 based on the new position of x2
y2 = y1 + dy * dx / dxo;
// Recalculate the distance on y axis
dyo = dy = y2 - y1;
dy1 = labs(dy);
}
// Recalculate a coordinate for y1 that is inside the screen bounds
if (y1 < 0 || y1 > yres)
{
// Set the new y1 to be at the edge of the screen
y1 = (y1 < 0) ? 0 : yres;
// Recalculate the distance on y axis
dy = y2 - y1;
dy1 = labs(dy);
// Calculate the new x1 based on the new position of y1
x1 = x2 - dx * dy / dyo;
// Recalculate the distance on x axis
dx = x2 - x1;
dx1 = labs(dx);
}
// Recalculate a coordinate for y2 that is inside the screen bounds
if (y2 < 0 || y2 > yres)
{
// Set the new y2 to be at the edge of the screen
y2 = (y2 < 0) ? 0 : yres;
// Recalculate the distance on y axis
dy = y2 - y1;
dy1 = labs(dy);
// Calculate the new x2 based on the new position of y2
x2 = x1 + dx * dy / dyo;
// Recalculate the distance on x axis
dx = x2 - x1;
dx1 = labs(dx);
}

int px = 2 * dy1 - dx1;
int py = 2 * dx1 - dy1;
if (dy1 <= dx1)
Expand Down