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: