DirectX9 3D 快速上手 6

** DirectX9 3D ** ** 快速上手 ** ** 6

** By sssa2000

** 4/25/2005 ** **

讲了很多，最基础的部分就剩下纹理没有讲到了。 Texture 是 Directx 里面非常重要的一部分。为了简便起见，我们还是以 SDK 的 Tutorial 5 为例子。

纹理就像一张墙纸，用来贴在物体的表面，当然，如果足够大，贴一次就能覆盖整个物体的表面，也可以用适当的方法让纹理排列成你要的效果。

来看看纹理的比较重要的函数： Device.SetTexture

public void SetTexture (
int stage , // 纹理混合阶段序号，从 0 开始
BaseTexture texture // _ 要设置的纹理对象 _
);

public void SetTextureStageState (
int stage , // 纹理混合阶段序号
TextureStageStates state , // TextureStageStates enumeration 的成员
int value // _ 对应阶段状态的值 _
);

** SetTextureStageState ** ** 函数对处理不同的纹理坐标，颜色操作， Alpha ** ** 操作，和凹凸映射 / ** ** 环境映射比较适用，但是这些操作只对 DX9 ** ** 的固定功能的多纹理单元有效，不能将他们与像素 shader ** ** 连用。

public void SetSamplerState (
int stage , // 纹理混合阶段序号
SamplerStageStates state , // SamplerStageStates enumeration 的成员
int _value // _ _ 对应采样器状态的值 _
);

知道了这些下面读懂这些代码就很容易了，我们需要建立 Vertex ，这里我们需要有一点点地改变，在以前我们接触到的 Vertex 里面都不涉及到纹理，所以我们选择了 CustomVertex 里面不包括纹理的类型，现在我们要用 CustomVertex.PositionNormalTextured ，从名字就可以看出来，这个类型包括了法线还包括了位置的 X,Y,Z ，以及纹理坐标的 Tu 和 Tv 。

当然如果使用 CustomVertex.PositionTextured 也是可以的，它不包括法线信息。

接下来我们需要为每个 Vertex 指定信息，我们先打断一下讲讲纹理坐标，为了通过指定纹理坐标来访问纹理中的每个图素， DX 采用了一个一般化的编址方案，纹理地址由 [0.0,1.0] 区间内的坐标组成，这样我们就不用关心纹理的实际尺寸，例如可以使用 ( 0.0f , 0.0f ) ,( 1.0f , 0.0f ),( 1.0f , 1.0f ),( 0.0f , 1.0f ) 把一个纹理贴到一个矩形上，同样如果 ( 0.0f , 0.0f ) ,(0 。 5f , 0.0f ),(0.5, 1.0f ),( 0.0f , 1.0f ) 就是纹理的左半边。

我们可以通过 TextureLoader.FromFile 方法来读入图片作为纹理。

这里代码很简单里面有详细的注释，我就不多讲了，

//-----------------------------------------------------------------------------

// File: texture.cs

// Desc: Better than just lights and materials, 3D objects look much more

// convincing when texture-mapped. Textures can be thought of as a sort

// of wallpaper, that is shrinkwrapped to fit a texture. Textures are

// typically loaded from image files, and D3DX provides a utility to

// function to do this for us. Like a vertex buffer, textures have

// Lock() and Unlock() functions to access (read or write) the image

// data. Textures have a width, height, miplevel, and pixel format. The

// miplevel is for "mipmapped" textures, an advanced performance-

// enhancing feature which uses lower resolutions of the texture for

// objects in the distance where detail is less noticeable. The pixel

// format determines how the colors are stored in a texel. The most

// common formats are the 16-bit R 5G 6B5 format (5 bits of red, 6-bits of

// green and 5 bits of blue) and the 32-bit A8R 8G 8B8 format (8 bits each

// of alpha, red, green, and blue).

// Textures are associated with geometry through texture coordinates.

// Each vertex has one or more sets of texture coordinates, which are

// named tu and tv and range from 0.0 to 1.0. Texture coordinates can be

// supplied by the geometry, or can be automatically generated using

// Direct3D texture coordinate generation (which is an advanced feature).

//-----------------------------------------------------------------------------

using System;

using System.Drawing;

using System.Windows.Forms;

using Microsoft.DirectX;

using Microsoft.DirectX.Direct3D;

using Direct3D=Microsoft.DirectX.Direct3D;

namespace TextureTutorial

{

public class Textures : Form

{

// Our global variables for this project

Device device = null ; // Our rendering device

VertexBuffer vertexBuffer = null ;

Texture texture = null ;

PresentParameters presentParams = new PresentParameters();

bool pause = false ;

public Textures()

{

// Set the initial size of our form

this .ClientSize = new System.Drawing.Size(400,300);

// And its caption

this .Text = "Direct3D Tutorial 5 - Textures";

}

public bool InitializeGraphics()

{

try

{

presentParams.Windowed= true ; // We don't want to run fullscreen

presentParams.SwapEffect = SwapEffect.Discard; // Discard the frames

presentParams.EnableAutoDepthStencil = true ; // Turn on a Depth stencil

presentParams.AutoDepthStencilFormat = DepthFormat.D16; // And the stencil format

device = new Device(0, DeviceType.Hardware, this , CreateFlags.SoftwareVertexProcessing, presentParams); //Create a device

device.DeviceReset += new System.EventHandler( this .OnResetDevice);

this .OnCreateDevice(device, null );

this .OnResetDevice(device, null );

pause = false ;

return true ;

}

catch (DirectXException)

{

// Catch any errors and return a failure

return false ;

}

public void OnCreateDevice( object sender, EventArgs e)

{

Device dev = (Device)sender;

// Now Create the VB

vertexBuffer = new VertexBuffer( typeof (CustomVertex.PositionNormalTextured), 100, dev, Usage.WriteOnly, CustomVertex.PositionNormalTextured.Format, Pool.Default);

vertexBuffer.Created += new System.EventHandler( this .OnCreateVertexBuffer);

this .OnCreateVertexBuffer(vertexBuffer, null );

}

public void OnResetDevice( object sender, EventArgs e)

{

Device dev = (Device)sender;

// Turn off culling, so we see the front and back of the triangle

dev.RenderState.CullMode = Cull.None;

// Turn off D3D lighting

dev.RenderState.Lighting = false ;

// Turn on the ZBuffer

dev.RenderState.ZBufferEnable = true ;

// Now create our texture

texture = TextureLoader.FromFile(dev, Application.StartupPath + @"\..\..\banana.bmp");

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