How to reflect a beam of light on a mirror using cycles? In the context of a tutorial, I need to create this experience using a light spot on cycle engine. We can replace persons with other objects.  I tried to do it using this answer  but the mirror does not reflect the light. here is my .blend . Any help?
reflecting direct light on glossy surface in Cycles Working in Cycles.  Say I have a "disco ball" with a glossy shader. I'm pointing a spot light to it, and I'm trying to have the reflections of that light illuminate the diffuse material on the walls with the patterns from the ball.    I get this:    but I'd like to get something like:    For the illustration I placed a point light inside the ball an removed faces. But what I'd like to do is move the light around the ball so that the light reflected from it changes like it would do in real life.   Is that possible at this point?  EDIT:  Just for the record here's the image rendered in LuxRender (yet another program to learn...)
Smoke Generator does not work When I try to run the smoke simulator in Blender 2.62 I get no smoke at all. When I attempt to render, the only output is a black screen. What am I doing wrong here that is making the smoke simulation not render?  Is it a mistake I made, or a problem with Blender version 2.62? Do there Exist Proper Classes that aren't "Too Big" Some proper classes are "too big" to be a set in the sense that they have a subclass that can be put in bijection with $\alpha$ for every cardinal $\alpha$. It is implied in  post that every proper class is "too big" to be a set in this sense, however I have been unable to prove it. It's true if every two proper classes are in bijection, but it's consistent with ZFC for there to be a pair of non-bijective classes.  So, is the following true in ZFC:     For all proper classes, $C$, and $\alpha\in\mathbf{Card}$, $\exists S\subset C$ such that $|S|=\alpha$?   If not, is there something reasonable similar that preserves the intuition about classes that are "too big to be sets"? Table with 100 % width and vertical / horizontal alignment I want to draw the following table in LaTeX. In the first column the text should be left aligned. The text in all other cells should be centered. The first problem occurs with D in the first row. If I write a \centering in front of D, I get a LaTeX error. The second problem is, that I want to vertically align the text in all cells but I don't know how. I have found a solution but it doesn't work if the width of the first column is specified.  \documentclass{article} \usepackage{blindtext} \usepackage{tabularx}  \begin{document}   \begin{tabularx}{\textwidth}{|p{4cm}|X|X|X|X|}     \hline                &amp; \centering A &amp; \centering B &amp; \centering C &amp; D\\     \hline     \blindtext &amp; 123 &amp; 123 &amp; 123 &amp; 123\\     \hline   \end{tabularx} \end{document} Restoring backups failing Ubuntu 16.04 Frobenius Inequality Rank I was looking for an answer for this problem in terms of matrices, but I really don't know how to prove this result. The proposition says that:  Let $A\in M_{m\times k}(\mathbb{C})$, $B\in M_{k\times p}(\mathbb{C})$ and $C\in M_{p\times n}(\mathbb{C})$, then $\textrm{rank}(AB)+\textrm{rank}(BC)\leq \textrm{rank}(B)+\textrm{rank}(ABC)$ To prove that if $n$ is odd, then $8 \mid n^2−1$, observe that as $n$ is odd either $n = 4k+1$ for some integer $k$ or $n=4k+3$ for some integer $k$. In the first case $n^2 -1=8(2k^2+k)$ and in the second case $n^2-1 = 8(2k^2 + 3k + 1)$.  Given an odd integer $a$, establish that $a^2 +(a+2)^2 +(a+4)^2 + 1$ is divisible by $12$. Solve by consideration of six cases. Ok guys, continuing my passage through edwards... here is the question... thanks for hints/solutions in advance:  Suppose $f(x,y,z)=0$ can be solved for each of the three variables $x,y,z$ as a differentiable function of the other two. Then prove that  $\displaystyle \frac{\partial x}{\partial y} \frac{\partial y}{\partial z} \frac{\partial z}{\partial x} = -1$  Verify this is the case for the ideal gas equation $pv =RT$ where (where $p,v,T$ are the three variables and $R$ is the constant). How do I start with in-camera JPEG settings in Lightroom? I'm a novice shooting in RAW and find that half the time my camera JPEG images come out better than my Lightroom tweaks to RAW files.  So to give myself a better start I'd like to apply the JPEG settings that are applied automatically by the camera to my RAW files in lightroom so that initially my RAW files look exactly like the JPEG files.   How can I do this? I have a query where I chain two columns. Why does the alias not work in the GROUP BY clause but in ORDER BY clause, it does work? How can I write the select correctly?  SELECT   KOS_VER_ID        AS "Vertrag"   , WHR_ISO_3_CODE  AS "Waehrung"   , KOS_KOA_ST_KZN || '  -  ' || ST_LANGBEZ_EN as "Kostenart"   , SUM (KOS_BETRAG) AS "Summe pro KOA" FROM   KOSTEN   , WAEHRUNG   , SCHLUESSELTABELLE WHERE    KOSTEN.KOS_VERHI_WHR_ID = WAEHRUNG.WHR_ISO_ID   AND KOSTEN.KOS_KOA_ST_KZN = SCHLUESSELTABELLE.ST_ID   AND KOS_VER_ID in (2509, 2510, 2511) GROUP BY   KOS_VER_ID   , WHR_ISO_3_CODE   , KOS_KOA_ST_KZN || '  -  ' || ST_LANGBEZ_EN ORDER BY   "Vertrag"   , "Kostenart" ; I know there is a ton of questions and answers about this topic, but none answers my question sufficiently.  Let's say I have a viewport view that I want to render in Cycles. Pressing ALT CTRL Numpad 0 aligns the camera to this view, but it does not solve the whole problem. The thing is, I want PRECISELY this view on the render, preferably in one click, without manually moving the camera back-and-forth, changing sensor sizes etc. fiddling that will remove the unwanted border that appears and blocks the viewport partially. This whole activity wastes a lot of precious time especially if you do this 10 times a day.  What this dream action should do:   match the render resolution (proportions) to the resolution of the current view (can the resolution of current view be read by a Python script?) make the entire view the camera view, without any borders, passe-partout etc. by automatically maneuvering sensor sizes etc. whatever is necessary to make it exactly the same view, the same camera lens angle.   Is it possible to write such a script that would do it all in one click? Suppose $f(x)$ is linear i.e. $f(x + y) = f(x) +f(y) $ and monotone on $[-\infty, +\infty]$, then $f(x) = ax$, a real. Suppose $f(x)$ is linear i.e. $f(x + y) = f(x) +f(y) $ and monotone on $[-\infty, +\infty]$, then $f(x) = ax$, a real.  We know $f(0)=0$, and if one assumes differentiability it is quite easy.      But how does monotone make up for differentiability? Plurality of verb depending on plurality of list elements This question is also open on EL&amp;U:   Considering the amount of controversy it aroused, I believe it's past "Learners'" level.    An edit was suggested to my sentence.     There was were an orange, some grapes, two apples and a small pile of cherries on the plate.   In my native language plurality of the verb always follows plurality of the first element on the list. There were an orange,... sounds awkward to me, no matter what follows up. My simple solution was reordering:     There were some grapes, an orange, two apples and a small pile of cherries on the plate.   But that's not the first time I faced this situation and I'd like to know what the rules of grammar say about that — was my editor overzealous or am I trying to copy rules of my language that don't apply in English? How can I compute the number of lists of the form $(a_1,\ldots,a_k)$, where $a_i \geq 0$ are integers and $\sum a_i \leq n$? What is the easiest way to derive the answer? Simulating group_concat MySQL function in Microsoft SQL Server 2005? Let's stop displaying a user's accept rate Fit mixture of distributions to your time-series data in R I have time-series data containing 1440 observations and the plot of the data is   I want to fit the Gaussian Mixture Models (GMM) to the above plot, and for the same I am using Mclust function of  package. Finally, I want a fit somewhat like this:   On using Mclust function, I do get following statistics     mclus_data &lt;- Mclust(givendataseries)    &gt; summary(mclus_data) ---------------------------------------------------- Gaussian finite mixture model fitted by EM algorithm  ----------------------------------------------------  Mclust E (univariate, equal variance) model with 8 components:   log.likelihood    n df      BIC      ICL        9525.438 1440 16 18934.52 18183.67  Clustering table:    1    2    3    4    5    6    7    8  1262    0    0    0    0   13  114   51    In the above statistic, I can not understand following:   Significance of log.likelihood, BIC and ICL. I can understand what each of them is, but what their magnitude/value refers to? It shows there are 8 clusters, but why cluster no. 2,3,4,5 has 0 values? What does this mean? From the plot it is clear that there must be two Guassians, but why Mclust function shows there are 8 Guassians?   Update: Actually, I want to do model based clustering of time series data. But currently  I want to fit the distribution to my raw data, as shown in Figure 1 on page no. 3 of  paper. For your quick reference, mentioned figure in said paper is Why can I only change my Stack Overflow name once every 30 days? I have a  on Stack Overflow. I recently decided to change the name on my profile. I did this, but I made a spelling mistake! I wrote "Kryton" instead of "Kryten"! When I tried to fix this, a message came back saying that I can only change my profile name every 30 days. Why? Is there any way I can fix my profile name? The final state of 1000 light bulbs switched on/off by 1000 people passing by There are  1000  light bulbs and 1000 tutors. All light bulbs are off. Tutor 1 goes flipping light bulb 1,2,3,4... tutor 2 then flips 2,4,6,8... tutor 3 then 3,6,9...etc until all 1000 tutors have done this.  What is the status of light bulb 25? 93? 576?  Is there a general solution to find out the status of any light bulb?  How many light bulbs are on after all 1000 tutors have gone by?  Not homework but a UK university interview question. Please help. Invoking shader in DX So I am new to the DX12 world. I am currently trying to tweek the nbody_gravity DX12 sample, but appending or calling another Compute Shader which is to add 2 buffers to produce an output in a different buffer.   I have written this code in "ComputeShader.hlsl" however when i tried to invoke it using the following, i get an error sayin "file not found" When i printed the debug error it says the following: D3D12GetDebugInterface: This method requires the D3D12 SDK Layers for Windows 10, but they are not present on the system.   I am invoking my shader after the default invocation to the nBodyGravity.hlsl is done:  ComPtr&lt;ID3DBlob&gt; computeShader; ComPtr&lt;ID3DBlob&gt; computeShader_m;  #if defined(_DEBUG)         // Enable better shader debugging with the graphics debugging tools.         UINT compileFlags = D3DCOMPILE_DEBUG | D3DCOMPILE_SKIP_OPTIMIZATION; #else         UINT compileFlags = 0; #endif           ThrowIfFailed(D3DCompileFromFile(GetAssetFullPath(L"NBodyGravityCS.hlsl").c_str(), nullptr, nullptr, "CSMain", "cs_5_0", compileFlags, 0, &amp;computeShader, nullptr));  //extra call for my shader ComPtr&lt;ID3DBlob&gt; error_ptr;         ThrowIfFailed(D3DCompileFromFile(GetAssetFullPath(L"ComputeShader.hlsl").c_str(), nullptr, nullptr, "main", "cs_5_0", compileFlags, 0, &amp;computeShader_m, &amp;error_ptr));  if (error_ptr) {     OutputDebugStringA((char *)error_ptr-&gt;GetBufferPointer()); }   Is there somthing amiss? Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop We all know you can't do the following because of ConcurrentModificationException:  for (Object i : l) {     if (condition(i)) {         l.remove(i);     } }   But this apparently works sometimes, but not always. Here's some specific code:  public static void main(String[] args) {     Collection&lt;Integer&gt; l = new ArrayList&lt;&gt;();      for (int i = 0; i &lt; 10; ++i) {         l.add(4);         l.add(5);         l.add(6);     }      for (int i : l) {         if (i == 5) {             l.remove(i);         }     }      System.out.println(l); }   This, of course, results in:  Exception in thread "main" java.util.ConcurrentModificationException   Even though multiple threads aren't doing it. Anyway.  What's the best solution to this problem? How can I remove an item from the collection in a loop without throwing this exception?  I'm also using an arbitrary Collection here, not necessarily an ArrayList, so you can't rely on get.