XNA-3D-draw triangles

1. Draw triangles in 3D space

1. Create an xNa windows game project and add member variables:

 
1: vertexpositioncolor [] vertices;
 
 
2: vertexbuffer;
 
 
3:
 
 
4: basiceffect;
 
 
5: Matrix world;
 
6: matrix view;
 
 
7: matrix projection;
 
 
2. initialize the triangle vertex coordinates and the world, view, and projection matrices in the initialize () method:
 
 
1: vertices =NewVertexpositioncolor []
 
 
2 :{
 
3:NewVertexpositioncolor (NewVector3 (0, 0), color. Red ),
 
 
4:NewVertexpositioncolor (NewVector3 (1,-1, 0), color. Green ),
 
 
5:NewVertexpositioncolor (NewVector3 (-1,-1, 0), color. Blue)
 
6 :};
 
 
7: vertexbuffer =NewVertexbuffer (graphicsdevice,
 
 
8:Typeof(Vertexpositioncolor ),
 
 
9: vertices. length,
 
 
10: bufferusage. None );
 
11: vertexbuffer. setdata <vertexpositioncolor> (vertices );
 
 
12: graphicsdevice. setvertexbuffer (vertexbuffer );
 
 
13:
 
 
14: World = matrix. identity;
 
15: view = matrix. createlookat (NewVector3 (0, 0, 5), vector3.zero, vector3.up );
 
 
16: Projection = matrix. createperspectivefieldofview (mathhelper. piover4,
 
 
17: graphicsdevice. viewport. aspectratio,
 
 
18: 1f,
 
19: 100f );
 
 
20:
 
 
21: basiceffect =NewBasiceffect (graphicsdevice );
 
 
22: basiceffect. vertexcolorenabled =True;
 
 
3. Draw a triangle in the draw () method:
 
1: basiceffect. World = World;
 
 
2: basiceffect. view = view;
 
 
3: basiceffect. Projection = projection;
 
 
4:
 
 
5: foreach (VAR passInBasiceffect. currenttechnique. Passes)
 
6 :{
 
 
7: Pass. Apply ();
 
 
8: graphicsdevice. drawuserprimitives <vertexpositioncolor> (
 
 
9: primitivetype. trianglelist,
 
 
10: vertices,
 
11: 0,
 
 
12: 1 );
 
 
13 :}
 
 
4. Running result:
 
 
 
 
Ii. Coordinate Transformation
 
In the update () method, respond to the keyboard button event and perform Coordinate Transformation:
 
 
1: keyboardstate = keyboard. getstate ();
 
2:If(Keyboardstate. iskeydown (Keys. R ))
 
 
3 :{
 
 
4: matrix rototez = matrix. createrotationz (mathhelper. piover4 );
 
 
5: World * = rototez;
 
 
6 :}
 
7:Else If(Keyboardstate. iskeydown (Keys. Left ))
 
 
8 :{
 
 
9: matrix translateleft = matrix. createtranslation (NewVector3 (-0.25f, 0, 0 ));
 
 
10: World * = translateleft;
 
11 :}
 
 
12:Else If(Keyboardstate. iskeydown (Keys. Right ))
 
 
13 :{
 
 
14: matrix translateright = matrix. createtranslation (NewVector3 (0.25f, 0, 0 ));
 
15: World * = translateright;
 
 
16 :}
 
3. Tips
 
To set the initial window size, you can modify the properties in the game constructor:
 
 
 1: graphics. preferredbackbufferwidth = 400; 
 
 2: graphics. preferredbackbufferheight = 300;