GPU Drawing - lines not 1px wide?

[Ego Eram Reputo]

I've created this little French Tiling plugin. Can someone please tell me why it is rendering a 2px thick lines? (I expected a single pixel).

 

Something to do with AA maybe?

 

// Name:
// Submenu:
// Author:
// Title:
// Version:
// Desc:
// Keywords:
// URL:
// Help:

// For help writing a GPU Drawing plugin: https://boltbait.com/pdn/CodeLab/help/tutorial/drawing/

#region UICode
IntSliderControl tileSize = 10; // [8,100] Tile size
IntSliderControl numberOfRows = 100; // [2,100] Number of Rows
IntSliderControl numberOfColumns = 100; // [2,100] Number of Columns
IntSliderControl hOffset = 0; // [0,5] Left to Right offset
IntSliderControl vOffset = 0; // [0,5] Top to Bottom offset
#endregion

protected override unsafe void OnDraw(IDeviceContext deviceContext)
{
    // TODO: replace this DrawImage statement with your GPU Drawing statements
    deviceContext.DrawImage(Environment.SourceImage);

    // define the pattern
    int[,] tilePattern = {
        {3,3,1,3,2,0},
        {1,2,0,3,1,3},
        {0,3,3,2,0,2},
        {0,2,3,1,1,2},
        {3,1,2,0,0,3},
        {2,0,3,1,3,1}
    };

    ISolidColorBrush outlineBrush = deviceContext.CreateSolidColorBrush(LinearColors.Black);

    for (int row = 0; row < numberOfRows; row++)
    {
        for (int col = 0; col < numberOfColumns; col++)
        {
            int x = col * tileSize;
            int y = row * tileSize;

            switch (tilePattern[(row+vOffset) % 6, (col+hOffset) % 6])
            {
                case 0:
                    // No borders on this cell
                    break;
                case 1:
                    // North border only
                    deviceContext.DrawLine(x,y,x+tileSize,y,outlineBrush);
                    break;
                case 2:
                    // West border only
                    deviceContext.DrawLine(x,y,x,y+tileSize,outlineBrush);
                    break;
                case 3:
                    // Both North and West borders
                    deviceContext.DrawLine(x,y,x+tileSize,y,outlineBrush);
                    deviceContext.DrawLine(x,y,x,y+tileSize,outlineBrush);
                    break;
            }
        }
    }
}

 

[Rick Brewster]

I'll refer you to an old Stack Overflow answer I did back in 2012: https://stackoverflow.com/a/10773729/1191082

 

Let me know if you still have questions!

[Ego Eram Reputo]

Thanks Rick!!

 

Alright. I have something that is.......workable

 

// Name:
// Submenu:
// Author:
// Title:
// Version:
// Desc:
// Keywords:
// URL:
// Help:

// For help writing a GPU Drawing plugin: https://boltbait.com/pdn/CodeLab/help/tutorial/drawing/

#region UICode
IntSliderControl tileSize = 10; // [8,100] Tile size
IntSliderControl numberOfRows = 100; // [2,100] Number of Rows
IntSliderControl numberOfColumns = 100; // [2,100] Number of Columns
IntSliderControl hOffset = 0; // [0,5] Left to Right offset
IntSliderControl vOffset = 0; // [0,5] Top to Bottom offset
#endregion

protected override unsafe void OnDraw(IDeviceContext deviceContext)
{
    // TODO: replace this DrawImage statement with your GPU Drawing statements
    deviceContext.DrawImage(Environment.SourceImage);

    // define the pattern
    int[,] tilePattern = {
        {3,3,1,3,2,0},
        {1,2,0,3,1,3},
        {0,3,3,2,0,2},
        {0,2,3,1,1,2},
        {3,1,2,0,0,3},
        {2,0,3,1,3,1}
    };

    ISolidColorBrush outlineBrush = deviceContext.CreateSolidColorBrush(LinearColors.Black);

    for (int row = 0; row < numberOfRows; row++)
    {
        for (int col = 0; col < numberOfColumns; col++)
        {
            float x = col * tileSize+0.5f;
            float y = row * tileSize+0.5f;

            Point2Float start = new Point2Float(x, y);
            Point2Float endX = new Point2Float(x+tileSize+0.5f, y);
            Point2Float endY = new Point2Float(x,y+tileSize+0.5f);

            switch (tilePattern[(row+vOffset) % 6, (col+hOffset) % 6])
            {
                case 0:
                    // No borders on this cell
                    break;
                case 1:
                    // North border only
                    deviceContext.DrawLine(start,endX,outlineBrush);
                    break;
                case 2:
                    // West border only
                    deviceContext.DrawLine(start,endY,outlineBrush);
                    break;
                case 3:
                    // Both North and West borders
                    deviceContext.DrawLine(start,endX,outlineBrush);
                    deviceContext.DrawLine(start,endY,outlineBrush);
                    break;
            }
        }
    }
}

 

Feels a bit hacky, but it 's not like I'm going to release it

 

[toe_head2001]

16 minutes ago, Ego Eram Reputo said:

Feels a bit hacky

 

Indeed. You don't need to offset each point.

You can set the offset once with UseTranslateTransform.

https://forums.getpaint.net/topic/131297-gpu-drawing-lines-not-1px-wide/

 

[Ego Eram Reputo]

59 minutes ago, toe_head2001 said:

 

Indeed. You don't need to offset each point.

You can set the offset once with UseTranslateTransform.

https://forums.getpaint.net/topic/131297-gpu-drawing-lines-not-1px-wide/

 

Thanks for that. Can't believe that thread has exactly the same title - and yet I missed it

[toe_head2001]

30 minutes ago, Ego Eram Reputo said:

Can't believe that thread has exactly the same title - and yet I missed it

 

It didn't... those posts were deeply buried in another forum topic, and I split them out.