CSharpGL(29)初步封装Texture和Framebuffer
Posted 天下事有难易乎
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了CSharpGL(29)初步封装Texture和Framebuffer相关的知识，希望对你有一定的参考价值。
+BIT祝威+悄悄在此留下版了个权的信息说：
CSharpGL(29)初步封装Texture和Framebuffer
+BIT祝威+悄悄在此留下版了个权的信息说：
Texture和Framebuffer
Texture和Framebuffer是OpenGL进行3D渲染高级效果必不可少的利器。有了Texture和Framebuffer就可以实现体渲染(Volume Rendering)等效果。现在到了对Texture和Framebuffer的创建、修改、使用进行封装的时候。
+BIT祝威+悄悄在此留下版了个权的信息说：
下载
CSharpGL已在GitHub开源，欢迎对OpenGL有兴趣的同学加入（https://github.com/bitzhuwei/CSharpGL）
+BIT祝威+悄悄在此留下版了个权的信息说：
封装Texture
过程式的Texture
首先观察一下平时是如何创建和使用Texture对象的。
+BIT祝威+悄悄在此留下版了个权的信息说：
创建Texture
以创建2D Texture为例。
1 uint CreateTexture(Bitmap bitmap) 2 { 3 glActiveTexture(OpenGL.GL_TEXTURE0); 4 var id = new uint[1]; 5 OpenGL.GenTextures(1, id); 6 OpenGL.BindTexture(target, id[0]); 7 OpenGL.TexParameteri(OpenGL.GL_TEXTURE_2D, OpenGL.GL_TEXTURE_WRAP_R, (int)OpenGL.GL_CLAMP_TO_EDGE); 8 OpenGL.TexParameteri(OpenGL.GL_TEXTURE_2D, OpenGL.GL_TEXTURE_WRAP_S, (int)OpenGL.GL_CLAMP_TO_EDGE); 9 OpenGL.TexParameteri(OpenGL.GL_TEXTURE_2D, OpenGL.GL_TEXTURE_WRAP_T, (int)OpenGL.GL_CLAMP_TO_EDGE); 10 OpenGL.TexParameteri(OpenGL.GL_TEXTURE_2D, OpenGL.GL_TEXTURE_MIN_FILTER, (int)OpenGL.GL_REPEAT); 11 OpenGL.TexParameteri(OpenGL.GL_TEXTURE_2D, OpenGL.GL_TEXTURE_MAG_FILTER, (int)OpenGL.GL_REPEAT); 12 13 BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), 14 ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb); 15 OpenGL.TexImage2D(OpenGL.GL_TEXTURE_2D, 0, OpenGL.GL_RGBA, bitmap.Width, bitmap.Height, 0, OpenGL.GL_BGRA, OpenGL.GL_UNSIGNED_BYTE, bitmapData.Scan0); 16 bitmap.UnlockBits(bitmapData); 17 18 return id[0]; 19 }
使用Texture
使用上述Texture的方式：
1 void UseTexture(string textureNameInShader, uint textureId) 2 { 3 uint target = OpenGL.GL_TEXTURE0; 4 glActiveTexture(target); 5 OpenGL.BindTexture(OpenGL.GL_TEXTURE_2D, textureId); 6 SetUniform("textureNameInShader", target - OpenGL.GL_TEXTURE0); 7 } 8 9 int SetUniform(string uniformName, uint v0) 10 { 11 int location = GetUniformLocation(uniformName); 12 if (location >= 0) 13 { 14 glUniform1ui(GetUniformLocation(uniformName), v0); 15 } 16 return location; 17 }
封装的Texture
从上述创建Texture的过程可知，创建Texture主要有2个步骤：设置Sampler和填充Texture数据。Sampler就是各个滤波选项。填充数据就是用glTexImage2D()一类的命令指定Texture的内容。
1 void Initialize() 2 { 3 glActiveTexture(this.ActiveTexture); 4 OpenGL.GenTextures(1, id); 5 BindTextureTarget target = this.Target; 6 OpenGL.BindTexture(target, id[0]); 7 this.Sampler.Bind(this.ActiveTexture - OpenGL.GL_TEXTURE0, target); 8 this.ImageFiller.Fill(target); 9 OpenGL.GenerateMipmap((MipmapTarget)((uint)target));// TODO: does this work? 10 //this.SamplerBuilder.Unbind(OpenGL.GL_TEXTURE0 - OpenGL.GL_TEXTURE0, this.Target); 11 OpenGL.BindTexture(this.Target, 0); 12 }
+BIT祝威+悄悄在此留下版了个权的信息说：
Sampler
Sampler中主要就是那几个滤波选项。
1 /// <summary> 2 /// texture\'s settings. 3 /// </summary> 4 public class SamplerParameters 5 { 6 public TextureWrapping wrapS = TextureWrapping.ClampToEdge; 7 public TextureWrapping wrapT = TextureWrapping.ClampToEdge; 8 public TextureWrapping wrapR = TextureWrapping.ClampToEdge; 9 public TextureFilter minFilter = TextureFilter.Linear; 10 public TextureFilter magFilter = TextureFilter.Linear; 11 12 public SamplerParameters() { } 13 }
+BIT祝威+悄悄在此留下版了个权的信息说：
Sampler的唯一任务就是在创建Texture时指定某些滤波。
1 /// <summary> 2 /// texture\'s settings. 3 /// </summary> 4 public abstract class SamplerBase 5 { 6 protected MipmapFilter mipmapFilter; 7 public SamplerParameters Parameters { get; protected set; } 8 9 /// <summary> 10 /// texture\'s settings. 11 /// </summary> 12 /// <param name="parameters"></param> 13 /// <param name="mipmapFilter"></param> 14 public SamplerBase(SamplerParameters parameters, MipmapFilter mipmapFilter) 15 { 16 if (parameters == null) 17 { 18 this.Parameters = new SamplerParameters(); 19 } 20 else 21 { 22 this.Parameters = parameters; 23 } 24 25 this.mipmapFilter = mipmapFilter; 26 } 27 28 /// <summary> 29 /// 30 /// </summary> 31 /// <param name="unit">OpenGL.GL_TEXTURE0 etc.</param> 32 /// <param name="target"></param> 33 public abstract void Bind(uint unit, BindTextureTarget target); 34 35 }
实际上为了简化指定Sampler的操作，OpenGL提供了一个Sampler对象。这里顺便也把它封装了。
1 /// <summary> 2 /// texture\'s settings. 3 /// </summary> 4 public partial class Sampler : SamplerBase, IDisposable 5 { 6 /// <summary> 7 /// sampler\'s Id. 8 /// </summary> 9 public uint Id { get; private set; } 10 11 /// <summary> 12 /// texture\'s settings. 13 /// </summary> 14 /// <param name="parameters"></param> 15 /// <param name="mipmapFiltering"></param> 16 public Sampler( 17 SamplerParameters parameters = null, 18 MipmapFilter mipmapFiltering = MipmapFilter.LinearMipmapLinear) 19 : base(parameters, mipmapFiltering) 20 { 21 22 } 23 24 private bool initialized = false; 25 /// <summary> 26 /// 27 /// </summary> 28 public void Initialize(uint unit, BindTextureTarget target) 29 { 30 if (!this.initialized) 31 { 32 this.DoInitialize(unit, target); 33 this.initialized = true; 34 } 35 } 36 37 private void DoInitialize(uint unit, BindTextureTarget target) 38 { 39 var ids = new uint[1]; 40 OpenGL.GenSamplers(1, ids); 41 this.Id = ids[0]; 42 //OpenGL.BindSampler(unit, ids[0]); 43 OpenGL.BindSampler(unit, ids[0]); 44 /* Clamping to edges is important to prevent artifacts when scaling */ 45 OpenGL.SamplerParameteri(ids[0], OpenGL.GL_TEXTURE_WRAP_R, (int)this.parameters.wrapR); 46 OpenGL.SamplerParameteri(ids[0], OpenGL.GL_TEXTURE_WRAP_S, (int)this.parameters.wrapS); 47 OpenGL.SamplerParameteri(ids[0], OpenGL.GL_TEXTURE_WRAP_T, (int)this.parameters.wrapT); 48 /* Linear filtering usually looks best for text */ 49 OpenGL.SamplerParameteri(ids[0], OpenGL.GL_TEXTURE_MIN_FILTER, (int)this.parameters.minFilter); 50 OpenGL.SamplerParameteri(ids[0], OpenGL.GL_TEXTURE_MAG_FILTER, (int)this.parameters.magFilter); 51 // TODO: mipmap not used yet. 52 53 OpenGL.BindSampler(unit, 0); 54 } 55 /// <summary> 56 /// texture\'s settings. 57 /// </summary> 58 /// <param name="unit">OpenGL.GL_TEXTURE0 etc.</param> 59 /// <param name="target"></param> 60 public override void Bind(uint unit, BindTextureTarget target) 61 { 62 if (!this.initialized) { this.Initialize(unit, target); } 63 64 OpenGL.BindSampler(unit, this.Id); 65 } 66 }
+BIT祝威+悄悄在此留下版了个权的信息说：
当然也可以不用这个OpenGL的Sampler对象，直接用glTexParameteri()等指令。这就像是一个假的Sampler对象在工作。
1 /// <summary> 2 /// texture\'s settings. 3 /// </summary> 4 public class FakeSampler : SamplerBase 5 { 6 7 /// <summary> 8 /// texture\'s settings. 9 /// </summary> 10 /// <param name="parameters"></param> 11 /// <param name="mipmapFiltering"></param> 12 public FakeSampler(SamplerParameters parameters, MipmapFilter mipmapFiltering) 13 : base(parameters, mipmapFiltering) 14 { 15 } 16 17 /// <summary> 18 /// texture\'s settings. 19 /// </summary> 20 /// <param name="unit">OpenGL.GL_TEXTURE0 etc.</param> 21 /// <param name="target"></param> 22 public override void Bind(uint unit, BindTextureTarget target) 23 { 24 /* Clamping to edges is important to prevent artifacts when scaling */ 25 OpenGL.TexParameteri((uint)target, OpenGL.GL_TEXTURE_WRAP_R, (int)this.parameters.wrapR); 26 OpenGL.TexParameteri((uint)target, OpenGL.GL_TEXTURE_WRAP_S, (int)this.parameters.wrapS); 27 OpenGL.TexParameteri((uint)target, OpenGL.GL_TEXTURE_WRAP_T, (int)this.parameters.wrapT); 28 /* Linear filtering usually looks best for text */ 29 OpenGL.TexParameteri((uint)target, OpenGL.GL_TEXTURE_MIN_FILTER, (int)this.parameters.minFilter); 30 OpenGL.TexParameteri((uint)target, OpenGL.GL_TEXTURE_MAG_FILTER, (int)this.parameters.magFilter); 31 // TODO: mipmap filter not working yet. 32 33 } 34 }
当然，有的时候根本不需要指定任何滤波选项。这可以用一个空的Sampler类型实现。
1 /// <summary> 2 /// do nothing about sampling in building texture. 3 /// </summary> 4 public class NullSampler : SamplerBase 5 { 6 /// <summary> 7 /// do nothing about sampling in building texture. 8 /// </summary> 9 public NullSampler() : base(null, MipmapFilter.LinearMipmapLinear) { } 10 11 /// <summary> 12 /// do nothing. 13 /// </summary> 14 /// <param name="unit">OpenGL.GL_TEXTURE0 etc.</param> 15 /// <param name="target"></param> 16 public override void Bind(uint unit, BindTextureTarget target) 17 { 18 // nothing to do. 19 } 20 }
+BIT祝威+悄悄在此留下版了个权的信息说：
ImageFiller
填充数据就是用 glTexImage2D() 、 glTexStorage2D() 等指令设置Texture的内容。ImageFiller就是封装这一操作的。
1 /// <summary> 2 /// build texture\'s content. 3 /// </summary> 4 public abstract class ImageFiller 5 { 6 7 /// <summary> 8 /// build texture\'s content. 9 /// </summary> 10 /// <param name="target"></param> 11 public abstract void Fill(BindTextureTarget target); 12 }
对于常见的以 System.Drawing.Bitmap 为数据源填充Texture的情形，可以用下面的BitmapFiller。它可以作为1D/2D的Texture对象的填充器。
1 /// <summary> 2 /// build texture\'s content with Bitmap. 3 /// </summary> 4 public class BitmapFiller : ImageFiller 5 { 6 private System.Drawing.Bitmap bitmap; 7 private int level; 8 private uint internalformat; 9 private int border; 10 private uint format; 11 private uint type; 12 13 /// <summary> 14 /// build texture\'s content with Bitmap. 15 /// </summary> 16 /// <param name="bitmap"></param> 17 /// <param name="level">0</param> 18 /// <param name="internalformat">OpenGL.GL_RGBA etc.</param> 19 /// <param name="border">0</param> 20 /// <param name="format">OpenGL.GL_BGRA etc.</param> 21 /// <param name="type">OpenGL.GL_UNSIGNED_BYTE etc.</param> 22 public BitmapFiller(System.Drawing.Bitmap bitmap, 23 int level, uint internalformat, int border, uint format, uint type) 24 { 25 this.bitmap = bitmap; 26 this.level = level; 27 this.internalformat = internalformat; 28 this.border = border; 29 this.format = format; 30 this.type = type; 31 } 32 33 /// <summary> 34 /// build texture\'s content with Bitmap. 35 /// </summary> 36 /// <param name="target"></param> 37 public override void Fill(BindTextureTarget target) 38 { 39 // generate texture. 40 // Lock the image bits (so that we can pass them to OGL). 41 BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), 42 ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb); 43 if (target == BindTextureTarget.Texture1D) 44 { 45 OpenGL.TexImage1D((uint)target, 0, this.internalformat, bitmap.Width, 0, this.format, this.type, bitmapData.Scan0); 46 } 47 else if (target == BindTextureTarget.Texture2D) 48 { 49 OpenGL.TexImage2D((uint)target, 0, this.internalformat, bitmap.Width, bitmap.Height, 0, this.format, this.type, bitmapData.Scan0); 50 } 51 else 52 { throw new NotImplementedException(); } 53 54 // Unlock the image. 55 bitmap.UnlockBits(bitmapData); 56 } 57 }
还有一个常见的填充方式 glTexStorage2D() ，可以用下面的TexStorageImageFiller实现。
1 /// <summary> 2 /// 3 /// </summary> 4 public class TexStorageImageFiller : ImageFiller 5 { 6 private int levels; 7 private uint internalFormat; 8 private int width; 9 private int height; 10 11 /// <summary> 12 /// 13 /// </summary> 14 /// <param name="levels"></param> 15 /// <param name="internalFormat"></param> 16 /// <param name="width"></param> 17 /// <param name="height"></param> 18 public TexStorageImageFiller(int levels, uint internalFormat, int width, int height) 19 { 20 // TODO: Complete member initialization 21 this.levels = levels; 22 this.internalFormat = internalFormat; 23 this.width = width; 24 this.height = height; 25 } 26 27 /// <summary>以上是关于CSharpGL(29)初步封装Texture和Framebuffer的主要内容，如果未能解决你的问题，请参考以下文章