c++ - DirectX 11 纹理闪烁

Question

如果您查看附加的 gif，特别是圆圈(可能需要缩放它才能看到问题)，会出现奇怪的效果。就像在翻译纹理时像素会发生轻微变化。我不确定为什么。和方 block 中央的那条蓝线一样，似乎在微微来回移动。我是 DirectX 的新手，所以不知道是什么原因造成的。

DirectX 设置代码:

// Create a DirectX graphics interface factory.
result = CreateDXGIFactory(__uuidof(IDXGIFactory), (void**)&factory);
Error::ErrorCheck(result, TEXT("CreateDXGIFactory()"));

// Use the factory to create an adapter for the primary graphics interface (video card).
result = factory->EnumAdapters(0, &adapter);
Error::ErrorCheck(result, TEXT("factory->EnumAdapters()"));

// Enumerate the primary adapter output (monitor).
result = adapter->EnumOutputs(0, &adapterOutput);
Error::ErrorCheck(result, TEXT("adapter->EnumOutputs()"));

// Get the number of modes that fit the DXGI_FORMAT_R8G8B8A8_UNORM display format for the adapter output (monitor).
result = adapterOutput->GetDisplayModeList(DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_ENUM_MODES_INTERLACED, &numModes, NULL);
Error::ErrorCheck(result, TEXT("adapterOutput->GetDisplayModeList()"));

// Create a list to hold all the possible display modes for this monitor/video card combination.
displayModeList = new DXGI_MODE_DESC[numModes];

// Now fill the display mode list structures.
result = adapterOutput->GetDisplayModeList(DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_ENUM_MODES_INTERLACED, &numModes, displayModeList);
Error::ErrorCheck(result, TEXT("adapterOutput->GetDisplayModeList()"));

// Now go through all the display modes and find the one that matches the screen width and height.
// When a match is found store the numerator and denominator of the refresh rate for that monitor.
for(i=0; i<numModes; i++)
{
    if(displayModeList[i].Width == (unsigned int)screenWidth)
    {
        if(displayModeList[i].Height == (unsigned int)screenHeight)
        {
            numerator = displayModeList[i].RefreshRate.Numerator;
            denominator = displayModeList[i].RefreshRate.Denominator;
        }
    }
}

// Get the adapter (video card) description.
result = adapter->GetDesc(&adapterDesc);
Error::ErrorCheck(result, TEXT("adapter->GetDesc()"));

// Store the dedicated video card memory in megabytes.
m_videoCardMemory = (int)(adapterDesc.DedicatedVideoMemory / 1024 / 1024);

// Convert the name of the video card to a character array and store it.
error = wcstombs_s(&stringLength, m_videoCardDescription, 128, adapterDesc.Description, 128);

// Release the display mode list.
delete [] displayModeList;
displayModeList = 0;

// Release the adapter output.
adapterOutput->Release();
adapterOutput = 0;

// Release the adapter.
adapter->Release();
adapter = 0;

// Release the factory.
factory->Release();
factory = 0;

// Initialize the swap chain description.
ZeroMemory(&swapChainDesc, sizeof(swapChainDesc));

// Set to a single back buffer.
swapChainDesc.BufferCount = 1;

// Set the width and height of the back buffer.
swapChainDesc.BufferDesc.Width = screenWidth;
swapChainDesc.BufferDesc.Height = screenHeight;

// Set regular 32-bit surface for the back buffer.
swapChainDesc.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;

// Set the refresh rate of the back buffer.
if(m_vsync_enabled)
{
    swapChainDesc.BufferDesc.RefreshRate.Numerator = numerator;
    swapChainDesc.BufferDesc.RefreshRate.Denominator = denominator;
}
else
{
    swapChainDesc.BufferDesc.RefreshRate.Numerator = 0;
    swapChainDesc.BufferDesc.RefreshRate.Denominator = 1;
}

// Set the usage of the back buffer.
swapChainDesc.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;

// Set the handle for the window to render to.
swapChainDesc.OutputWindow = hwnd;

// Turn multisampling off.
swapChainDesc.SampleDesc.Count = 1;
swapChainDesc.SampleDesc.Quality = 0;

// Set to full screen or windowed mode.
if(fullscreen)
{
    swapChainDesc.Windowed = false;
}
else
{
    swapChainDesc.Windowed = true;
}

// Set the scan line ordering and scaling to unspecified.
swapChainDesc.BufferDesc.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED;
swapChainDesc.BufferDesc.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;

// Discard the back buffer contents after presenting.
swapChainDesc.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;

// Don't set the advanced flags.
swapChainDesc.Flags = 0;

// Set the feature level to DirectX 11.
featureLevel = D3D_FEATURE_LEVEL_11_0;

// Create the swap chain, Direct3D device, and Direct3D device context.
result = D3D11CreateDeviceAndSwapChain(NULL, D3D_DRIVER_TYPE_HARDWARE, NULL, 0, &featureLevel, 1, 
                       D3D11_SDK_VERSION, &swapChainDesc, &m_swapChain, &m_device, NULL, &m_deviceContext);
Error::ErrorCheck(result, TEXT("D3D11CreateDeviceAndSwapChain()"));

// Get the pointer to the back buffer.
result = m_swapChain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&backBufferPtr);
Error::ErrorCheck(result, TEXT("m_swapChain->GetBuffer()"));

// Create the render target view with the back buffer pointer.
result = m_device->CreateRenderTargetView(backBufferPtr, NULL, &m_renderTargetView);
Error::ErrorCheck(result, TEXT("m_swapChain->GetBuffer()"));

// Release pointer to the back buffer as we no longer need it.
backBufferPtr->Release();
backBufferPtr = 0;

// Initialize the description of the depth buffer.
ZeroMemory(&depthBufferDesc, sizeof(depthBufferDesc));

// Set up the description of the depth buffer.
depthBufferDesc.Width = screenWidth;
depthBufferDesc.Height = screenHeight;
depthBufferDesc.MipLevels = 1;
depthBufferDesc.ArraySize = 1;
depthBufferDesc.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;
depthBufferDesc.SampleDesc.Count = 1;
depthBufferDesc.SampleDesc.Quality = 0;
depthBufferDesc.Usage = D3D11_USAGE_DEFAULT;
depthBufferDesc.BindFlags = D3D11_BIND_DEPTH_STENCIL;
depthBufferDesc.CPUAccessFlags = 0;
depthBufferDesc.MiscFlags = 0;

// Create the texture for the depth buffer using the filled out description.
result = m_device->CreateTexture2D(&depthBufferDesc, NULL, &m_depthStencilBuffer);
Error::ErrorCheck(result, TEXT("m_device->CreateTexture2D()"));

// Initialize the description of the stencil state.
ZeroMemory(&depthStencilDesc, sizeof(depthStencilDesc));

// Set up the description of the stencil state.
depthStencilDesc.DepthEnable = true;
depthStencilDesc.DepthWriteMask = D3D11_DEPTH_WRITE_MASK_ALL;
depthStencilDesc.DepthFunc = D3D11_COMPARISON_LESS;

depthStencilDesc.StencilEnable = true;
depthStencilDesc.StencilReadMask = 0xFF;
depthStencilDesc.StencilWriteMask = 0xFF;

// Stencil operations if pixel is front-facing.
depthStencilDesc.FrontFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;
depthStencilDesc.FrontFace.StencilDepthFailOp = D3D11_STENCIL_OP_INCR;
depthStencilDesc.FrontFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;
depthStencilDesc.FrontFace.StencilFunc = D3D11_COMPARISON_ALWAYS;

// Stencil operations if pixel is back-facing.
depthStencilDesc.BackFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;
depthStencilDesc.BackFace.StencilDepthFailOp = D3D11_STENCIL_OP_DECR;
depthStencilDesc.BackFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;
depthStencilDesc.BackFace.StencilFunc = D3D11_COMPARISON_ALWAYS;

// Create the depth stencil state.
result = m_device->CreateDepthStencilState(&depthStencilDesc, &m_depthStencilState);
Error::ErrorCheck(result, TEXT("m_device->CreateDepthStencilState()"));

// Set the depth stencil state.
m_deviceContext->OMSetDepthStencilState(m_depthStencilState, 1);

// Initailze the depth stencil view.
ZeroMemory(&depthStencilViewDesc, sizeof(depthStencilViewDesc));

// Set up the depth stencil view description.
depthStencilViewDesc.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;
depthStencilViewDesc.ViewDimension = D3D11_DSV_DIMENSION_TEXTURE2D;
depthStencilViewDesc.Texture2D.MipSlice = 0;

// Create the depth stencil view.
result = m_device->CreateDepthStencilView(m_depthStencilBuffer, &depthStencilViewDesc, &m_depthStencilView);
Error::ErrorCheck(result, TEXT("m_device->CreateDepthStencilView()"));

// Bind the render target view and depth stencil buffer to the output render pipeline.
m_deviceContext->OMSetRenderTargets(1, &m_renderTargetView, m_depthStencilView);

// Setup the raster description which will determine how and what polygons will be drawn.
rasterDesc.AntialiasedLineEnable = false;
rasterDesc.CullMode = D3D11_CULL_NONE;
rasterDesc.DepthBias = 0;
rasterDesc.DepthBiasClamp = 0.0f;
rasterDesc.DepthClipEnable = true;
rasterDesc.FillMode = D3D11_FILL_SOLID;
rasterDesc.FrontCounterClockwise = false;
rasterDesc.MultisampleEnable = false;
rasterDesc.ScissorEnable = false;
rasterDesc.SlopeScaledDepthBias = 0.0f;

// Create the rasterizer state from the description we just filled out.
result = m_device->CreateRasterizerState(&rasterDesc, &m_rasterState);
Error::ErrorCheck(result, TEXT("m_device->CreateRasterizerState()"));

// Now set the rasterizer state.
m_deviceContext->RSSetState(m_rasterState);

// Setup the viewport for rendering.
viewport.Width = (float)screenWidth;
viewport.Height = (float)screenHeight;
viewport.MinDepth = 0.0f;
viewport.MaxDepth = 1.0f;
viewport.TopLeftX = 0.0f;
viewport.TopLeftY = 0.0f;

// Create the viewport.
m_deviceContext->RSSetViewports(1, &viewport);

纹理顶点设置/更新代码

void Bitmap::InitializeBuffers(ID3D11Device* device) {
VertexType* vertices;
unsigned long* indices;
D3D11_BUFFER_DESC vertexBufferDesc, indexBufferDesc;
D3D11_SUBRESOURCE_DATA vertexData, indexData;
HRESULT result;
int i;

// Set the number of vertices in the vertex array.
m_vertexCount = 6;

// Set the number of indices in the index array.
m_indexCount = m_vertexCount;

// Create the vertex array.
vertices = new VertexType[m_vertexCount];

// Create the index array.
indices = new unsigned long[m_indexCount];

// Initialize vertex array to zeros at first.
memset(vertices, 0, (sizeof(VertexType) * m_vertexCount));

// Load the index array with data.
for(i=0; i<m_indexCount; i++)
{
    indices[i] = i;
}

// Set up the description of the static vertex buffer.
vertexBufferDesc.Usage = D3D11_USAGE_DYNAMIC;
vertexBufferDesc.ByteWidth = sizeof(VertexType) * m_vertexCount;
vertexBufferDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER;
vertexBufferDesc.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;
vertexBufferDesc.MiscFlags = 0;
vertexBufferDesc.StructureByteStride = 0;

// Give the subresource structure a pointer to the vertex data.
vertexData.pSysMem = vertices;
vertexData.SysMemPitch = 0;
vertexData.SysMemSlicePitch = 0;

// Now create the vertex buffer.
result = device->CreateBuffer(&vertexBufferDesc, &vertexData, &m_vertexBuffer);
Error::ErrorCheck(result, TEXT("CreateBuffer()"));

// Set up the description of the static index buffer.
indexBufferDesc.Usage = D3D11_USAGE_DEFAULT;
indexBufferDesc.ByteWidth = sizeof(unsigned long) * m_indexCount;
indexBufferDesc.BindFlags = D3D11_BIND_INDEX_BUFFER;
indexBufferDesc.CPUAccessFlags = 0;
indexBufferDesc.MiscFlags = 0;
indexBufferDesc.StructureByteStride = 0;

// Give the subresource structure a pointer to the index data.
indexData.pSysMem = indices;
indexData.SysMemPitch = 0;
indexData.SysMemSlicePitch = 0;

// Create the index buffer.
result = device->CreateBuffer(&indexBufferDesc, &indexData, &m_indexBuffer);
Error::ErrorCheck(result, TEXT("CreateBuffer()"));

// Release the arrays now that the vertex and index buffers have been created and loaded.
delete [] vertices;
vertices = 0;

delete [] indices;
indices = 0;
}

void Bitmap::Render(ID3D11DeviceContext* deviceContext, int positionX, int positionY, bool flipped) {
// Re-build the dynamic vertex buffer for rendering to possibly a different location on the screen.
UpdateBuffers(deviceContext, positionX, positionY, flipped);

// Put the vertex and index buffers on the graphics pipeline to prepare them for drawing.
RenderBuffers(deviceContext);
}

void Bitmap::UpdateBuffers(ID3D11DeviceContext* deviceContext, int positionX, int positionY, bool flipped) {
int left, right, top, bottom;
VertexType* vertices;
D3D11_MAPPED_SUBRESOURCE mappedResource;
VertexType* verticesPtr;
HRESULT result;

// If the position we are rendering this bitmap to has not changed then don't update the vertex buffer since it
// currently has the correct parameters.
if((positionX == m_previousPosX) && (positionY == m_previousPosY)) {
    if(m_flipped == flipped) {
        return;
    }
}

// If it has changed then update the position it is being rendered to.
m_previousPosX = positionX;
m_previousPosY = positionY;

// Calculate the screen coordinates of the left side of the bitmap.
left = ((m_screenWidth / 2) * -1) + positionX;

// Calculate the screen coordinates of the right side of the bitmap.
right = left + m_bitmapWidth;

// Calculate the screen coordinates of the top of the bitmap.
top = (m_screenHeight / 2) - positionY;

// Calculate the screen coordinates of the bottom of the bitmap.
bottom = top - m_bitmapHeight;

// Create the vertex array.
vertices = new VertexType[m_vertexCount];

// Load the vertex array with data.
if(!flipped) {
    // First triangle.
    vertices[0].position = D3DXVECTOR3(left, top, 0.0f);  // Top left.
    vertices[0].texture = D3DXVECTOR2(0.0f, 0.0f);

    vertices[1].position = D3DXVECTOR3(right, bottom, 0.0f);  // Bottom right.
    vertices[1].texture = D3DXVECTOR2(1.0f, 1.0f);

    vertices[2].position = D3DXVECTOR3(left, bottom, 0.0f);  // Bottom left.
    vertices[2].texture = D3DXVECTOR2(0.0f, 1.0f);

    // Second triangle.
    vertices[3].position = D3DXVECTOR3(left, top, 0.0f);  // Top left.
    vertices[3].texture = D3DXVECTOR2(0.0f, 0.0f);

    vertices[4].position = D3DXVECTOR3(right, top, 0.0f);  // Top right.
    vertices[4].texture = D3DXVECTOR2(1.0f, 0.0f);

    vertices[5].position = D3DXVECTOR3(right, bottom, 0.0f);  // Bottom right.
    vertices[5].texture = D3DXVECTOR2(1.0f, 1.0f);
} else {
    // First triangle.
    vertices[0].position = D3DXVECTOR3(left, top, 0.0f);  // Top left.
    vertices[0].texture = D3DXVECTOR2(1.0f, 0.0f);

    vertices[1].position = D3DXVECTOR3(right, bottom, 0.0f);  // Bottom right.
    vertices[1].texture = D3DXVECTOR2(0.0f, 1.0f);

    vertices[2].position = D3DXVECTOR3(left, bottom, 0.0f);  // Bottom left.
    vertices[2].texture = D3DXVECTOR2(1.0f, 1.0f);

    // Second triangle.
    vertices[3].position = D3DXVECTOR3(left, top, 0.0f);  // Top left.
    vertices[3].texture = D3DXVECTOR2(1.0f, 0.0f);

    vertices[4].position = D3DXVECTOR3(right, top, 0.0f);  // Top right.
    vertices[4].texture = D3DXVECTOR2(0.0f, 0.0f);

    vertices[5].position = D3DXVECTOR3(right, bottom, 0.0f);  // Bottom right.
    vertices[5].texture = D3DXVECTOR2(0.0f, 1.0f);
}

m_flipped = flipped;

// Lock the vertex buffer so it can be written to.
result = deviceContext->Map(m_vertexBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mappedResource);
Error::ErrorCheck(result, TEXT("deviceContext->Map()"));

// Get a pointer to the data in the vertex buffer.
verticesPtr = (VertexType*)mappedResource.pData;

// Copy the data into the vertex buffer.
memcpy(verticesPtr, (void*)vertices, (sizeof(VertexType) * m_vertexCount));

// Unlock the vertex buffer.
deviceContext->Unmap(m_vertexBuffer, 0);

// Release the vertex array as it is no longer needed.
delete [] vertices;
vertices = 0;
}

void Bitmap::RenderBuffers(ID3D11DeviceContext* deviceContext)
{
unsigned int stride;
unsigned int offset;

// Set vertex buffer stride and offset.
stride = sizeof(VertexType); 
offset = 0;

// Set the vertex buffer to active in the input assembler so it can be rendered.
deviceContext->IASetVertexBuffers(0, 1, &m_vertexBuffer, &stride, &offset);

// Set the index buffer to active in the input assembler so it can be rendered.
deviceContext->IASetIndexBuffer(m_indexBuffer, DXGI_FORMAT_R32_UINT, 0);

// Set the type of primitive that should be rendered from this vertex buffer, in this case triangles.
deviceContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST);
}

Answer 1

你的问题是你没有考虑纹素的真实中心。它不在角落，而是在他的中心。

假设您有一个 256x256 的纹理，要读取左上角的像素，要使用的纹理坐标不是 float2(0,0) 而是 float2(0.5,0.5)/256 .f 右下角是float2(255.5,255.5)/256.f。

现在，在几何链 > 带投影的顶点着色器 > 视口(viewport) > 像素着色器中。您可以通过不同的方式应用偏移量。

我们可以在像素着色器中添加半纹理像素偏移，但这意味着以常量形式发送值或使用非常糟糕的 GetDimensions。您可以直接在几何体中执行此操作，但它使问题超出了我的口味(如果您执行隐式 UV 或位置怎么办？)。

对于您的情况，最简单且侵入性较小的解决方案是在顶点着色器的末尾应用偏移，通过在正交投影中烘焙它或直​​接调整投影位置。

投影空间在 X 轴和 Y 轴上映射一个尺寸为 ]-1..1[ 的正方形，稍后由视口(viewport)以实际屏幕坐标(以像素为单位)进行变换。如果我们假设几何体的纹理坐标在 [0..1] 范围内，那么这段代码将解决您的问题:

float4 projPos; // this is your current vertex shader output sv_position 
projPos.xy -= projPos.w * 1.f / backBufferDim.xy;

因为 GPU 将除以 W，我们需要通过乘以 W 来取消它，并且因为投影空间的 len 为 2，投影空间中的半像素偏移量是该偏移量的两倍，所以你使用后台缓冲区维度的倒数。

有了那条线，纹理坐标的插值将为您工作，并且您的像素着色器将接收到适当偏移的纹理坐标。