Nebula3绘制2D纹理

上次已经绘制过基本图元了, 这次只不过要贴张图而已.....

本来我想用Graphics的Model渲染流程来做, 不过这一层太高级了, 都是什么场景管理资源映射之类的

做低级的事情, 就要用低级的API嘛

图形渲染的底层是CoreGraphics, 这个层我不打算再单独写(翻译)一篇了, 因为都是Direct3D概念的一些抽象. 也就是说D3D用熟了基本上一看就明白(用GL的我就不清楚啦, 嘿嘿, N3的作者都放弃用GL去实现@_@).

还记得D3D Tutorial中的Textured例子不? 需要的东西有带纹理坐标的点, 纹理. N3中也一样, 不过, 这里没法用固定管线了.

N3的设计的时候就放弃了固定管线(多么明智呀, 别喷我-_-, 我只会shader.......), 所以在这之前我们要先写一个shader来进行绘制.

因为我们只是进行简单的演示, 就尽量简单了, 写一个2D的纹理绘制, 你可以用来做UI:

//------------------------------------------------------------------------------ // texture2d.fx // texture shader for 2D(UI) // (C) xoyojank //------------------------------------------------------------------------------ float2 halfWidthHeight : HalfWidthHeight; texture diffMap : DiffMap0; sampler diffMapSampler = sampler_state { Texture = <diffMap>; AddressU = Clamp; AddressV = Clamp; MinFilter = Point; MagFilter = Point; MipFilter = None; }; struct VS_INPUT { float3 pos : POSITION; float2 uv : TEXCOORD; }; struct VS_OUTPUT { float4 pos : POSITION; float2 uv : TEXCOORD; }; //------------------------------------------------------------------------------ /** */ VS_OUTPUT VertexShaderFunc(VS_INPUT input) { VS_OUTPUT output; output.pos.xy = float2(input.pos.x - halfWidthHeight.x, halfWidthHeight.y - input.pos.y) / halfWidthHeight; output.pos.zw = float2(input.pos.z, 1.0f); output.uv = input.uv; return output; } //------------------------------------------------------------------------------ /** */ float4 PixelShaderFunc(float2 uv : TEXCOORD0) : COLOR { return tex2D(diffMapSampler, uv); } //------------------------------------------------------------------------------ /** */ technique Default { pass p0 { ColorWriteEnable = RED|GREEN|BLUE|ALPHA; ZEnable = False; ZWriteEnable = False; StencilEnable = False; FogEnable = False; AlphaBlendEnable = True; SrcBlend = SrcAlpha; DestBlend = InvSrcAlpha; AlphaTestEnable = False; ScissorTestEnable = False; CullMode = CW; VertexShader = compile vs_3_0 VertexShaderFunc(); PixelShader = compile ps_3_0 PixelShaderFunc(); } }

值得一提的是CullMode =CW, 为什么? 因为N3用的右手坐标系, 这点又跟D3D不一样了........为什么呢? 难道写MAYA跟MAX的插件的时候比较省事?

还是要跟上一次一样设置顶点格式并载入VertexBuffer:

// vertex Array<VertexComponent> vertexComponents; vertexComponents.Append(VertexComponent(VertexComponent::Position, 0, VertexComponent::Float3)); vertexComponents.Append(VertexComponent(VertexComponent::TexCoord, 0, VertexComponent::Float2)); float vertex[4][5] = { {0.0f, 0.0f, 0.0f, 0.0f, 0.0f}, {0.0f, 256.0f, 0.0f, 0.0f, 1.0f}, {256.0f,0.0f, 0.0f, 1.0f, 0.0f}, {256.0f,256.0f, 0.0f, 1.0f, 1.0f} }; vertexBuffer = VertexBuffer::Create(); Ptr<MemoryVertexBufferLoader> vbLoader = MemoryVertexBufferLoader::Create(); vbLoader->Setup(vertexComponents, 4, vertex, 4 * 5 * sizeof(float)); vertexBuffer->SetLoader(vbLoader.upcast<ResourceLoader>()); vertexBuffer->Load(); vertexBuffer->SetLoader(NULL);

纹理的创建其实跟顶点差不多, 因为它都是属于资源的一种, 详见Nebula3资源子系统

// texture texture = Texture::Create(); texture->SetResourceId(ResourceId("bin:razor.jpg")); texture->SetLoader(StreamTextureLoader::Create()); texture->Load(); texture->SetLoader(NULL);

shader的加载跟上一次一样, 只是参数不同:

// shader this->shaderInstance = this->shaderServer->CreateShaderInstance(ResourceId("shd:texture2d")); Ptr<ShaderVariable> halfWidthHeight = this->shaderInstance->GetVariableBySemantic(ShaderVariable::Semantic("HalfWidthHeight")); float2 halfWH = float2(this->renderDevice->GetDefaultRenderTarget()->GetWidth(), this->renderDevice->GetDefaultRenderTarget()->GetHeight()) * 0.5f; halfWidthHeight->SetFloatArray(&halfWH.x(), 2); Ptr<ShaderVariable> diffMap = this->shaderInstance->GetVariableBySemantic(ShaderVariable::Semantic("DiffMap0")); diffMap->SetTexture(texture);

绘制嘛, 当然改成矩形了, 图片可贴不到一跟线上:

this->renderDevice->BeginFrame(); this->renderDevice->BeginPass(this->renderDevice->GetDefaultRenderTarget(), this->shaderInstance); PrimitiveGroup primGroup; primGroup.SetBaseVertex(0); primGroup.SetNumVertices(4); primGroup.SetPrimitiveTopology(PrimitiveTopology::TriangleStrip); this->renderDevice->SetVertexBuffer(this->vertexBuffer); this->renderDevice->SetPrimitiveGroup(primGroup); this->renderDevice->Draw(); this->renderDevice->EndPass(); this->renderDevice->EndFrame(); this->renderDevice->Present();

上图: