Game Structure - C# Game Programming: For Serious Game Creation - page 120

Setup2DGraphics(ClientSize.Width, ClientSize.Height);
_fastLoop = new FastLoop(GameLoop);
}
The projection matrix will need re-creating anytime the form changes size.
Therefore, a call to Setup2DGraphics should also be added to the On-
ClientSizeChanged callback.
protected override void OnClientSizeChanged(EventArgs e)
{
base.OnClientSizeChanged(e);
Gl.glViewport(0, 0, this.ClientSize.Width, this.ClientSize.Height);
Setup2DGraphics(ClientSize.Width, ClientSize.Height);
}
The title state renders a triangle, but the triangle's maximum width is only
1 OpenGL unit. The previous projection matrix had a width and height of 2 so the
triangle appeared a good size. The width and height of this new projection matrix
is 1280 and 720 so the triangle barely takes up a pixel and therefore cannot be seen!
An easy way to fix this is to make the triangle bigger. Find the triangle drawing
code and make the width and height 50 instead of 1.
Gl.glColor4d(1.0, 0.0, 0.0, 0.5);
Gl.glVertex3d(-50, 0, 0);
Gl.glColor3d(0.0, 1.0, 0.0);
Gl.glVertex3d(50, 0, 0);
Gl.glColor3d(0.0, 0.0, 1.0);
Gl.glVertex3d(0, 50, 0);
This will make the triangle visible once again. Most 2D graphics use two triangles
to make a quad. This quad then has a texture applied to it and forms the basis of
a 2D game or heads-up display.
Sprites
The first step of creating a sprite is to create a quad. A triangle is made of three
vertices; a quad is made of four. See Figure 6.5. A sprite is a pretty basic game
element, and it's a good idea to make it into its own class. There will also be a
class responsible for drawing the sprites. This class will be called the Renderer .
Before implementing the Renderer and Sprite classes, it's useful to first