// Draws a simple 2D line between two points
// create a SpriteBatch object named sprBatch

sprBatch is a SpriteBatch object called after Begin
create a simple 4x4 block for "spr"

"a" is the starting point of the line

"b" is the ending point of the line

"col" can be any color


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void DrawLine(SpriteBatch sprBatch, Texture2D spr, Vector2 a, Vector2 b, Color col)
{
     Vector2 Origin = new Vector2(0.5f, 0.0f);
     Vector2 diff =  b - a;
     float angle;
     Vector2 Scale = new Vector2(1.0f, diff.Length()/spr.Height);
 
     angle = (float)(Math.Atan2(diff.Y, diff.X))-MathHelper.PiOver2;
 
     sprBatch.Draw(spr, a, null, col, angle, Origin, Scale, SpriteEffects.None, 1.0f);
}