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:
代码语言：javascript复制//------------------------------------------------------------------------------
// 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:
代码语言：javascript复制// 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
代码语言：javascript复制 // 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:
代码语言：javascript复制// 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:
代码语言：javascript复制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:
