Introduction to XNA Graphics Programming Asst. Prof. Rujchai Ung-arunyawee COE, KKU.
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Transcript of Introduction to XNA Graphics Programming Asst. Prof. Rujchai Ung-arunyawee COE, KKU.
XNA Project Template Program Class
Main() method
Game1 Class Game1() method(constructor) Initialize() method LoadGraphicsContent() method UnloadGraphicsContent() method Update() method Draw() method GraphicsDeviceManager object ContentManager object
GraphicsDeviceManager object Required by every XNA application. Handles the configuration and
management of the graphics device. GraphicsDevice class is used for drawing
primitive-based objects. Declared as a member of the game class.
GraphicsDeviceManager graphics; Created in the game class constructor.
graphics = new GraphicsDeviceManager(this);
ContentManager Object Used to load, manage, and dispose of binary
media content through the content pipeline. Graphics and media content can be loaded
with this object when it is referenced in the game project.
Declared as a member of the game class.ContentManager content;
Created in the game class constructor.content = new ContentManager(Services);
Initialize() method Traps the one-time game startup event. Natural place to trigger basic setup activities
such as the following:Setting window properties such as the title or
full screen optionsSetting the perspective and view to define how
a user sees the 3D game Initializing image objects for displaying textures Initializing vertices for storing color, and image
coordinates to be used throughout the program
Initialize() method (cont.) Initializing vertex shaders to convert your
primitive objects to pixel output Initializing audio objectsSetting up other game objects
LoadGraphicsContent() method
For loading binary image and model content through the graphics pipeline.
UnloadGraphicsContent() method
For loading binary image and model content loaded in LoadGraphicsContent method the program exit.
Draw() method Handles the drawing (also known as
rendering) for the game program. Starts by clearing the screen background,
setting the screen color, and then drawing the graphics onto the screen.
Update() method Checks and handles game-time events.
mouse clicks, keyboard presses, game-pad control events, and timers
Also a place for many other activities that require continuous checks or updatesadvancing animations, detecting collisions,
and tracking and modifying game scores
XNA Vertex types A vertex stores information, which could include
X, Y, and Z positions, image coordinates, a normal vector, and color.
XNA Primitive Objects (cont.) Total triangle list vertices = Ntriangles * 3
vertices Total triangle strip vertices = Ntriangles + 2
vertices Total line list vertices = Nlines * 2 vertices Total line strip vertices = Nlines + 1 vertex
Drawing 3D in XNA uses shader-based rendering to convert
vertex data into pixel output must use a shader to draw 3D graphics Shaders can be used to manipulate all
vertex properties (e.g.,color, position, and texture)
Built-in shader class name BasicEffect you will need to write your own shader to
implement the effect
Using BasicEffect class Declared as member variable of the Game
classBasicEffect effect;
Created in Initialize() method effect = new BasicEffect(graphics.GraphicDevice,null);
Using BasicEffect class (cont.) Initialized in Initialize() method
// Calculate the effect aspect ratio, world, projection, and view matrix
GraphicsDevice device = graphics.GraphicsDevice;float aspectRatio = (float)device.Viewport.Width /
device.Viewport.Height; // Set the World Matrix effect.World = Matrix.Identity; // Set the Viewing Matrix effect.View = Matrix.CreateLookAt(new Vector3(0.0f, 0.0f, 2.0f), Vector3.Zero, Vector3.Up); // Set the Projection Matrix effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(60.0f), aspectRatio, 1.0f, 10.0f);
Using BasicEffect class (cont.) Used in Draw() method
effect.Begin();
foreach (EffectPass CurrentPass in effect.CurrentTechnique.Passes)
{
CurrentPass.Begin();
// draw here
device.DrawPrimitives(PrimitiveType.LineList, 0, 3);
CurrentPass.End();
}
effect.End();
Model construction1. Creates an array of vertex and assigns
value to them
2. Represents a list of 3D vertices to be streamed (VertexBuffer object)
Create and assign value to Vertex private void CreateModel() { // size of 3D Axis float axisLength = 1f; // Number of vertices we´ll use int vertexCount = 6;
VertexPositionColor[] vertices = new VertexPositionColor[vertexCount]; // X axis vertices[0] = new VertexPositionColor(new Vector3(-axisLength, 0.0f, 0.0f), Color.White); vertices[1] = new VertexPositionColor(new Vector3(axisLength, 0.0f, 0.0f), Color.White); // Y axis vertices[2] = new VertexPositionColor(new Vector3(0.0f, -axisLength, 0.0f), Color.White); vertices[3] = new VertexPositionColor(new Vector3(0.0f, axisLength, 0.0f), Color.White); // Z axis vertices[4] = new VertexPositionColor(new Vector3(0.0f, 0.0f, -axisLength), Color.White); vertices[5] = new VertexPositionColor(new Vector3(0.0f, 0.0f, axisLength), Color.White);
// fill the vertex buffer with the vertices vertexBuffer = new VertexBuffer(graphics.GraphicsDevice, vertexCount * VertexPositionColor.SizeInBytes, ResourceUsage.WriteOnly); vertexBuffer.SetData<VertexPositionColor>(vertices);
}
VertexBuffer object Declared as member variable of the Game
classVertexBuffer vertexBuffer;
Created and filled with the vertex array vertexBuffer = new VertexBuffer(graphics.GraphicsDevice,
vertexCount * VertexPositionColor.SizeInBytes,
ResourceUsage.WriteOnly);
vertexBuffer.SetData<VertexPositionColor>(vertices);
GraphicDevice Preparation for Drawing
Declare a correct vertex type to the graphic device
Set the vertex source of the graphic device to the game vertex buffer
GraphicsDevice device = graphics.GraphicsDevice;// Create a vertex declaration to be used when drawing the verticesdevice.VertexDeclaration = new VertexDeclaration(device, VertexPositionColor.VertexElements);// Set the vertex sourcedevice.Vertices[0].SetSource(vertexBuffer, 0, VertexPositionColor.SizeInBytes);