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Tsus

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About Tsus

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  1. Tsus

    How to calculate Lumens?

    @Hodgman: I have this vague feeling that it's not my place to correct you, but since you asked...     You're mixing photometric and radiometric terminology, here. Candela (cd) is the unit of luminous intensity (photometric). The equivalent radiometric quantity is radiant intensity and it's unit is watts per steradian.     Candela is lumen per solid angle.     The unit of luminance (photometric) is: cd/m²     @CGEngine: If I'm not totally mistaken, you can just plug the photometric units into the rendering equation. For some reason the (English) rendering literature often uses the radiometric names for the quantities (radiance, irradiance, ...), but is using photometric units (lumen, candela, ...), which is totally confusing.   The radiometric units are used in radiation physics. The photometric units are used whenever the human perception is concerned. (They just differ in the way how they weight light of different wavelengths. If you're not working with spectral lighting effects, you don't really need to care.)   The dot product formula you posted earlier is the photometric way of mixing RGB values into some luminance value (the weighting is according to the spectral response curves of the "average" eye).
  2. Hi axefrog,   I have some book references for you that cover at least the NURBS part.   "Fundamentals of Computer Aided Geometric Design" by Hoschek and Lasser is a standard reference for modeling with curves and surfaces. It also covers various methods for interpolation, intersections, blending and smoothing of surfaces.   In Farin's "Curves and Surfaces for Computer-Aided-Geometric-Design", there's a bit more background on continuity, splines, and different kinds of operations you can do with curves and surfaces. It also contains exercises.   Here are some applets that demonstrate a few of the algorithms discussed in those books.   Hope that helps a little. ;) Cheers!
  3. Tsus

    Depth stencil state issue

    Hi!   The black depth channel is somewhat expected, due to the non-linear distribution of the z-values. Right beside the combobox where you selected the "depth" channel, you have a gray bar that allows you to filter the range displayed linearly. There are tiny triangles (top-left at the bar, and bottom-right). These are the lower and upper bounds. You can move them around, so that you have the lower bound around 0.95. That should show you something.   On the top left of the window is a small "save" icon. You could save the PIXrun and upload it, so that we might have a look. Best, Tsus
  4. Tsus

    Depth stencil state issue

    Ok. So, with all resources being successfully created and no errors in the output window during draw calls, it's time to use a graphics debugger like PIX. PIX is contained in the DxSDK and allows you to capture the draw calls and states for a frame (every time you hit F12). When clicking on a draw call in the list presented to you in PIX, the vertices of the triangles are shown before and after transformation. If you do a right click on the rendering output you can debug individual pixels and see, why fragments were discarded. Also, you can dig into the states bound at a draw call. Hopefully, this sheds some light on the matter.
  5. Tsus

    Depth stencil state issue

    Hi eltharynd, Usually, CPU access flags are not required for the depth buffer. Try to turn on the debug layer, as eppo suggested. D3D will most probably tell you what is wrong. The behavior you described sounds like invalid parameters. Pass the flag D3D11_CREATE_DEVICE_DEBUG into the Flags parameter of the D3D11CreateDevice call. Could you check that all your mDevice->Create... methods return S_OK? If not, the debug layer will tell you in the Output window of visual studio, why the Create-method failed. (If you run in Debug mode with F5, not Ctrl+F5.) Clearing structs with ZeroMemory is a good practice (in my eyes). Could you do it for the depth stencil desc, too? (Just to be safe.) ZeroMemory (&dsDesc, sizeof(D3D11_DEPTH_STENCIL_DESC)); Also, you have some copy paste error when clearing the depth stencil view desc. It should go: ZeroMemory (&depthStencilViewDesc, sizeof(D3D11_DEPTH_STENCIL_VIEW_DESC)); Just to be safe, set a rasterizer state. Whenever you move code around, you don't want to depend on states of some previous code block. D3D11_RASTERIZER_DESC rsDesc; ZeroMemory(&rsDesc, sizeof(D3D11_RASTERIZER_DESC)); rsDesc.CullMode = D3D11_CULL_BACK; rsDesc.DepthBias = 0; rsDesc.DepthBiasClamp = 0; rsDesc.FillMode = D3D11_FILL_SOLID; rsDesc.AntialiasedLineEnable = false; rsDesc.DepthClipEnable = true; rsDesc.FrontCounterClockwise = true; rsDesc.MultisampleEnable = true; rsDesc.ScissorEnable = false; rsDesc.SlopeScaledDepthBias = 0; if (FAILED(mDevice->CreateRasterizerState(&rsDesc, &mRsBackfaceCulling))) return false; Then, later: mDeviceContext->RSSetState(mRsBackfaceCulling); And don't worry. You'll figure it out. Best, Tsus  
  6. Tsus

    Depth stencil state issue

    Hi eltharynd! If you don't need the stencil test, you probably want to disable it. dsDesc.StencilEnabled = false; In this case, you can put full precision into the depth value by using a full float for it: depthTexDesc.Format = DXGI_FORMAT_D32_FLOAT;   Currently, your depth testing function permits all fragments to be written. Instead, let only fragments through that have a smaller depth value. dsDesc.DepthFunc = D3D11_COMPARISON_LESS_EQUAL;   It might be just due to copy-pasting into the browser, but did you use the correct depth stencil view description, when creating the depth stencil view? (2nd argument changed) mDevice->CreateDepthStencilView(depthStencilTexture, &depthStencilViewDesc, &mDepthStencilView); I guess you did, but for completeness I'm just saying it: You bound your depth buffer like so, right? ID3D11RenderTargetView* rtvs[] = { mRenderTargetView_Backbuffer }; ImmediateContext->OMSetRenderTargets(1, rtvs, mDepthStencilView); Do you clear the depth stencil view before drawing? mImmediateContext->ClearDepthStencilView(mDepthStencilView, D3D11_CLEAR_DEPTH, 1, 0); Also, were all your resources successfully created? (That is, they are not NULL?) Best, Tsus
  7. Tsus

    blending question

    Hi! Will your float texture ever contain negative values? It's not strikingly elegant, but: in case you need to clear a pixel, you could write out a large negative value, giving you after the additive blending something that is smaller than zero. When you use the texture later, you could clamp the value again up to zero: max(0, texture_color).
  8. Tsus

    OIT with weighted average

    Hi,   Your suggestion is already the solution. So, yeah, you got it right. I'll summarize the steps briefly for you: Your transparent rendering would happen in the rendering loop after the deferred pass: Fill your deferred buffer (color, depth, …) Do the deferred lighting Render the transparent objects For the last step, do the following: Disable depth writing (glDepthMask) -> we want no transparent object to be culled by other transparent objects Enable depth test (glDepthTest) -> compare with your deferred depth buffer (cull by opaque geometry) Use additive blending (source: GL_ONE, dest: GL_ONE) Bind two new render targets; let’s call them AccumColors (four (half) float components) and AccumCount (single float component) Render the transparent objects into those two targets (explained in a moment) Bind deferred color buffer as render target Disable depth test (glDepthTest) Use back-to-front blending (source: GL_ONE_MINUS_SRC_ALPHA, dest: GL_SRC_ALPHA) Bind AccumColor and AccumCount as textures Full screen pass: compute the average color/transparency (explained in a moment) and blend with the deferred color buffer The idea is to compute the average of the colors, weighted by their transparencies. For blending with the background, we additionally need the average opacity. (FYI: I assume that alpha = 1 means opaque, and alpha = 0 means transparent)   Step 5 computes the sums. This is what the fragment shader does: Input: vec3 color, float alpha Output: AccumColor = vec4(color*alpha, alpha); // color multiplied (=weighted) with alpha! AccumCount = 1;   Step 10 compute the average color. Again, the fragment shader: Input: vec4 AccumColor, float AccumCount if (AccumCount < 0.00001 || AccumColor.w < 0.00001) {   discard;  // nothing here; discard the fragment. } else {   vec4 avgColor = vec4(   AccumColor.xyz / AccumColor.w,    // weighted average color   AccumColor.w / AccumCount);        // average alpha   // the alpha, used to blend with the background is computed by assuming // that all transparent layers have the average alpha:   float dstAlpha = 1-pow(max(0,1-avgColor.w), AccumCount);   // write out the average color and the alpha, used for compositing   result = vec4 (avgColor.xyz, dstAlpha); } Hope that gives some insights. Best regards!  
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