Clang supports a number of AArch64-specific attributes to manage state added by the Scalable Matrix Extension (SME). The any function determines if any components of the specified value are non-zero, while the all function determines if all components of the specified value are non-zero. Then we calculate the distance to the input value based on. If it is false, then you get 0, in whatever the output type is (floating-point types get 0. Well that is the thing, I do want to change these at runtime. {"payload":{"allShortcutsEnabled":false,"fileTree":{"OIT_DX11/AOIT Technique":{"items":[{"name":"AOIT. Creates a linker interface. The following code shows the HLSL closest hit shader that calculates shadows with a single point light from the sample app: #include "raycommon. glsl: // common code #pragma anki. It's also settled that a variable coming out of the vertex shader stage for example is varying (HLSL doesn't need this keyword at all!). First of all, I created a custom node which allows me to perform a Gaussian Blur on a Texture Object. The hlsl compiler thinks you want your float4s in registers even though your gpu might not have float4 registers at all. If we wish to add source annotations to more grammatical elements in the future we will encounter more ambiguities because the : character has other meanings in C and modern C++ as well. Get Cell Values 🔗︎. You can now read the entire book for free! GDC Talks. Anyway the HLSL compiler will, in general, attempt to unroll loops and flatten branches unless you try to convince it otherwise. And unrolling loops is one of those directives. Rendering. 2. shaders-msl-no-opt. Theme. Array reference can not be used as an l-value. A pattern such as for (int i = 0; i < n && i < MAX_N; ++i) gives a dynamic bound and allows the compiler to unroll (to nested if-statements). Loop aren't automatically unrolled, if you are. Reload to refresh your session. You need to declare blurLength as a static int for this to work. That's a no no. In HLSL, #include directives are a type of preprocessor directive. When the Custom node is selected, the. The loop condition depends on shader input, so I don't think that the processor is detecting a loop that it. cginc","path":"CGIncludes/AutoLight. 1 Answer. This could be a reason that fxc try to unroll the for loop so that the shader program is executed in lockstep mode. Visit Stack ExchangeTour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this siteQ&A for professional and independent game developers. The [branch] and [flatten] tags are just hints to the compiler to prefer one or the other if supported and possible. Hue, Saturation, and Lightness (HSL) is a method for describing colors. . #2 - External Code Editing and # include. When no attribute is specified, the compiler may use a hardware switch or emit a series of if statements. E. "3. g. The problem is DX9 & ShaderModel 3. Although you can use the geometry shader to sub-divide primitives, I would suggest looking into tessellation. hlsl This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. So, if you use dynamic branching excessively when you target these profiles, you can receive compilation errors. The DirectX 12 compiler DXC has received a PR about a month ago that adds template support to HLSL. First, the reason why the second one works, is because it is automatically unrolled. Geometry Shader. We start by implementing that in 2d. Hi all, There are some [Attribute] blocks in HLSL flow control statements: loop, unroll (x) -> for loop. Would a 50-iteration for loop have a significant performance impact during a pixel shader? I tried, just out of curiosity, setting the float4 lights array to have 250 elements, and the shader wouldn’t compile, saying. Q&A for professional and independent game developers. I have to do the Filtering with the variable filter size. HLSL Pixel Shader Sematics. Creating custom shaders in Unity 2020. 1), when I navigate to the URP Lit shader in my project directory (Packages > Universal RP > Shaders > Lit) and select it, I see that it has 2 errors, both about not being able to open include file 'LitInput. The ShaderLab syntax hasn’t changed much compared to the built-in pipeline. While it can do rendering, it is generally used for tasks not directly related to drawing triangles and pixels. yes (pixel shader only), but you must use the legacy compile option when compiling. Qiita Blog. #pragma anki frag_shader_begins. the last reply in that post was saying to change the route, but i tried to put the Common. vs","contentType":"directory"},{"name":"DXUT","path":"DXUT","contentType. Here is shader code: void DownsamplePass_Pixel_Shader ( in float4 Position : POSITION0, in float4 PositionSS : VPOS, out float4. January 19, 2009 10:59 PM. When unrolling a loop, the iteration count has to be a compile-time constant; without the static on there, the. 1 Hardware dependent. D3DCreateLinker. Instead I’m going to throw my Material asset (including comments) at you for everyone to use, adjust and play around with. New subject: [PATCH v4 1/1] vkd3d-shader/hlsl: Ignore "unroll" attribute for loops. A flow-control statement determines at run time which block of HLSL statements to execute next. hlsl". Example code: 1 #pragma unroll <N> 2 for (int i = 0; i < M; ++i) { 3 // Some useful work 4 } In this example, N specifies the unroll factor, that is, the number of copies of the loop that the HLS compiler generates. What does it mean? “If” flow controls in HLSL come in two flavors: “branch” and “flatten. these are hints for the hlsl compiler on how you want loop unrolling to be done. . 8. Name Template Type Component Type“@kanetaaaaa GLSLでも [loop] [unroll] を指定できるようにして、コンパイル速度と実効速度のトレードオフを簡単に制御できるようにして欲しいですよね😅 forでインライン展開を抑制するのは流石にハックすぎる😇”HLSL will let you do it, but when the shader is compiled all constant register accesses have to be explicit (static at compile-time). Sc4Freak. One way is using the HLS pragma as follows: const unsigned int N = 1024; const unsigned int B =. gitignore","path":". 0), Metal (MSL) and also other GLSL versions (GLSL 330, GLSL 400, etc. glsl”. The solution to this issue is either to make sure that the proper side is always facing the camera. Nikolay Sivov 14 Apr 2023 14 Apr '23Unfortantly, especially for pixel shader targets, there are very few cases where you can actually use a loop to do anything useful, most of the time the time HLSL has to unroll it. ARB_compute_shader. Topics tagged hlsl. Other shading languages. h","contentType":"file"},{"name":"NIS_Main. For example, you can specify -Oconfig=--loop-unroll,--scalar-replacement=300,--eliminate-dead-code-aggressive to firstly. このため、今回は…. glsl. Minimal working example Below is an MWE consisting of a C# script for Unity, the corresponding compute shader where the computations are performed and a screen-shot of my console when. UNROLL for (uint k = 0; k. I believe so, yes. Second question: whatever you want to do with that shader. ) basic types: all int/uint/float/double scalar/vector/matrix. Zebediah Figura (＠zfigura) Release for 1. 2 US English only for live captions, and voice access. I’ve successfully build all the binaries and trying to open the starter content. It’s also possible to add multiple active targets to the list, if you need it to be. Thanks for the reference. [fastopt] 및 [allow_uav_condition] 특성은 [unroll]이 지정된 경우 무시됩니다. 1 I didn't pick any of them. 0 wave ops Up to 6. It works with vs_3_0 and ps_3_0. vertical path hookup through to SPIR-V generation. hlsl","contentType. Note: When you use Shader Model 2. The [unroll] and [loop] attributes are mutually exclusive and will generate compiler errors when both are specified. Remarks. Each line begins with a regular expression followed by a statement written in C code. The regular for loops in HLSL compute shaders gives different results depending on the local computer it is ran on (see image below). I think the problem should be in material function or in custom node with HLSL but I found only two custom MF and seems like everything is ok with it. hlsl","path. I’ve successfully build all the binaries and trying to open the starter content. See also. It takes an array like { 1, 2, 1, 2 } and outputs the accumulative sum from left to right either exclusive { 0, 1, 3, 4 } or inclusive { 1, 3, 4, 6 }. Unroll 指令在 for 循环的代码区域进行优化，这个指令不包含流水线执行的概念，单纯地将循环体展开使用更多地硬件资源实现，保证并行循环体在调度地过程中是彼此独立的。. Touching this variable in shader caused compiler to unroll. High-level language GLSL & HLSL HLSL Intermediate language SPIR-V SPIR-V & DXIL Supported platform Windows, Linux, macOS Windows, Linux, macOS Compiler library size Small Big (LLVM/Clang) HLSL shader model Up to 5. I was able to piece together several other sources. ll and is processed by flex to produce C code. The reason it's forced to unroll that loop is because of that texture load and the way D3D handles automatic mip level calculations. I would like for this code to be dynamic so as to reduce the instruction count. // Object Declarations Texture2D g_MeshTexture; // Color texture for mesh SamplerState MeshTextureSampler { Filter =. When you design shader algorithms, keep the. Control structures (for-loops, if-else statements, etc) exist in GLSL, including the switch statement. It is a revisited itoa() function for HLSL producing resulting ascii codes in an array of uint. HLSL compilation speed. You switched accounts on another tab or window. This page contains information about using shader code blocks. Epic Developer Community Forums hlsl. D3DCreateLinker. Converts the specified value from degrees to radians. Well you have a few options: -Use a loop/ifs like you have. Can somebody help me with it? Update: I think I found HLSL code with that errors but still don’t know how to fix it:1 Answer. Remarks. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. If you comment out the blendedBiome [biome] line you should find it compiles fine. #pragma optimize( "s", on ) Using the optimize pragma with the empty string ("") is a special form of the directive:. As you can see in the above example, I have used HLSL shader semantics for input and output layout. When unrolling a loop, the iteration count has to be a compile-time constant; without the static on there, the compiler has to assume you might change the value of the parameter at runtime. 0 don't handle dynamic loop lengths well, so unrolled loops are generally better / faster and the compiler will try to unroll most of the time. @AusSkiller: Putting the declarations outside the for-loop, good idea!GLSL and SPIR-V define implicit derivatives as undefined in the specification in contrast to HLSL which seems to like these cases (e. 1, + 6. The Overflow Blog Build vs. Optionally, you can specify the maximum number of times the loop can execute. The decoder ring also has a translation table for concepts and terms used in. Shader has ~700 lines, which are compiled into ~3000 instructions. First, the reason why the second one works, is because it is automatically unrolled. from bool. Feedback. int count = min (iterCount, 4); for (int i = 0; i < count; ++i) {. com. HLSL-only or GLSL-only compute shaders. I'm coming from a DX9 background, using the now outdated FX framework, where uniform variables can be used as a sort of preprocessor value that changes the compilation of a shader. The compiler has to be able to fully unroll the loop. Specifically, this topic provides details about the following: Enable some of the old FXC compilation behaviors that are disabled by default on DXC. Resources Developer Site; Xilinx Wiki; Xilinx GithubNew subject: [PATCH v4 1/1] vkd3d-shader/hlsl: Ignore "unroll" attribute for loops. The attributes come in the form of type- and declaration attributes:In general the HLSL compiler likes to unroll loops whenever it can, which is typically when the number of iterations is known at compile time. meta","path. hlslHLSL 2021. -Put in blank textures to sample for the samplers that are unused, so, you always look them up. A shader-reflection interface accesses shader information. for语句. 0, each time you use dynamic branching you consume resources. New subject: [PATCH v3 1/1] vkd3d-shader/hlsl: Ignore "unroll" attribute for loops. Attribute Description; branch: Evaluate only one side of the if statement depending on the given condition. However sometimes that's not really an option, like when unrolling a loop makes a shader more than 65k instructions, or some other both artificial and spec limitations. Decluttering your inbox has never been so easy, or looked so good. A great starting point on using HLSL in Vulkan via SPIR-V is the HLSL to SPIR-V feature mapping manual. jpg","contentType":"file"},{"name":"Example. Topic Replies Views Activity; Niagara HLSL Troubleshoot. Now, let’s increase the performance by partially unroll the loop by the factor of B. I added that line "compile_arguments -unroll none" as described by Sinbad, but unfortunately that did not have any effect. You can put #pragma directives anywhere in your HLSL code, but it is a. . The converter can be downloaded from this page. This could be a problem for us. ShaderLab. 1 Answer. Discussion in 'Shader Graph' started by NarberalTools, May 3, 2021. Image Effect Shaders have culling off by default if you’d like to see an example. Compute Shader. Example. 추가 정보. . Or you could use HLSL to write a compute shader, perhaps to implement a physics. The joys of each vendor implementing. Featured on Meta Update: New Colors Launched. 2 HLSL validation No Yeshlsl; directive; or ask your own question. Imperfect loop nests cannot be flattened by the tool. Though obviously the shader would no longer do the job you want. {"payload":{"allShortcutsEnabled":false,"fileTree":{"Modules/Rendering/Shaders":{"items":[{"name":"vaASSAOLite. Loops in the C/C++ functions are kept rolled by default. For people who are having the opposite problem, you'd invoke it as "#pragma optionNV (unroll all)" in GLSL, but I think the following will prevent unrolling. So you need to pass a the array length to the shader. branch, flatten -> if statement. 3 comments, last. dynamic does not exist as a valid attribute. Example code: #pragma unroll <N> for (int i = 0; i < M; ++i) { // Some useful work } In this example, <N> specifies the unroll factor, that is, the number of copies of the loop that the. There's probably crap I'm missing but GLSL needs some help. // vertex #version 450 #extension GL_ARB_separate_shader_objects : enable out gl_PerVertex. The lexer tokenizes the HLSL input by matching regular expressions to corresponding tokens. gerstner_wave. Vega extends this by performing 16 bit math at. The HLSL reference documentation specifies the language characteristics. Unroll and loop work alongside the optimizing compiler, but are not substitute for it, nor can they be substituted by it. This could be a reason that fxc try to unroll the for loop so that the shader program is executed in lockstep mode. HLSL has two syntaxes for specifying source annotations. They provide additional information to the shader A program that runs on the GPU. It seems HLSL is prohibiting defining a struct nested inside a struct, so make sure to define your custom structs above and outside struct Functions. 0. Here’s how to use HLSL shaders in an existing app, created in the Vulkan Ray Tracing Tutorial written by NVIDIA engineers Martin-Karl Lefrançois and Pascal Gautron. Learn more about Teams{"payload":{"allShortcutsEnabled":false,"fileTree":{"CGIncludes":{"items":[{"name":"AutoLight. 흐름 제어Hi I am trying to unroll a large loop completely. Item Description; warning-specifier: Behavior to set for the specified warnings. ここのfor文で頂点シェーダーから貰った3つの頂点をそれぞれ射影変換しています。 そうすることにより、通常のレンダリングと同様にポリゴン位置を決めることが出来ます。. Compilation time is with fxc (Windows 8 SDK) about 90 seconds. This section of the manual includes information on using HLSL in a Unity-specific way. (UNITY_COMPILER_HLSL) [unroll(16)] #endif Or just remove that and let the shader. 1 Answer. Oct 24, 2007. non-streaming or streaming) as well as the state of the. Additional resources. When unrolling a loop, the iteration count has to be a compile-time constant; without the static on there, the compiler has to assume you might change the value of the parameter at runtime. 2. ) 등의 기타 쉐이더 언어와 매우 흡사합니다. Shader Model 4. Adding the unroll attribute to loops does not guarantee that the compiler is able to legalize the code. Hi everybody, I am currently encountering a problem with some HLSL custom node. "3. You can put #pragma directives anywhere in your HLSL code, but it is a. Typically, pixels outnumber vertices in a scene, so pixel shaders execute more often than vertex shaders. (UNITY_COMPILER_HLSL) [unroll(16)] #endif Or just remove that and let the shader. roots_n[i] is a dynamic access, and it's apparently only because the HLSL compiler is unrolling the loop that it recognizes that this expression will definitely perform an out-of-bounds access. Color. Loop unrolling, also known as loop unwinding, is a loop transformation technique that attempts to optimize a program's execution speed at the expense of its binary size, which is an approach known as space–time tradeoff. Share. HLSL中用于优化的指令，[branch],[flatten],[loop],[unroll] branch，shader会根据判断语句只执行当前情况的代码; flatten，shader会执行全部情况的分支代码，然后再根据判断条件获得结果; unroll，for循环是展开的，直到循环条件终止; loop，for循环不展开，Exit the surrounding loop (do, for, while). HLSL shaders can be compiled at author-time or at runtime, and set at runtime into the appropriate pipeline stage. Preprocessor directive that provides machine-specific or operating system-specific features while retaining overall compatibility with the C and C++ languages. cginc","contentType":"file"},{"name. 语义是附加到着色器输入或输出的字符串，用于传达有关参数的预期用途的信息。. How to make a custom semantics HLSL shader for the pixel shader. 5) * <complex formula>; Using HLSL's step () function (which returns 0 if the first param is greater and 1 if less), you can eliminate the branch, but now the <complex formula> is being called every time, and its results are being multiplied by 0 (thus wasted effort) half of the time. it will take one cycles to enter the loop and one cycle to exit the loop copy_A. This adds infrastructure suitable for any front end to create SPIR-V loop control flags. 8, but on the precedent of 1. [/font] [color=#282828][font=helvetica, arial, verdana, tahoma, sans-serif]dxc -E CSMandelJulia_scalarFloat -T cs_5_0 mandelfp16v2. 2 HLSL validation No Yes(update) check out post #3](Custom Stencil: Radial Silhouette Post Process Materiel (HLSL) (PC) (Full code) (4. Stop executing the current loop ( do, for, while ), update the loop conditions, and begin executing from the top of the loop. 1 Answer. We eventually need to implement the semantics of the HLSL [unroll] attribute in our back-end. Append(o) stream. Is possible to speed up the compilation from. Fragment Shader. If you do not want the compiler to unroll loops, use this attribute to reduce compile time. . You can now read the entire book for free! GDC Talks. generic preprocessor (same as GLSL) scanner (keywords, identifiers, etc. sponsored post. Features and app availability may vary by region. . Use flow-control statements in the compiled shader; do not unroll the loop. HLSL template support in UE4. Or in cases where both sides should be shown, you can turn culling off. So now, you can start to build a library of custom functions, and more complex shaders. Does the ATI or nVidia driver unroll the loops (SM 2. This results in additional clock cycles to enter and exit the loops. int count = min (iterCount, 4); for (int i = 0; i < count; ++i) {. If you used say tex2dlod (or a texture reading funciton that accepts the ddx and ddy parameters) it would be able to use a real loop. Get Cell Values 🔗︎. For example, you can use HLSL to write a vertex shader, or a pixel shader, and use those shaders in the implementation of the renderer in your Direct3D application. はじめに 今回は書いたことのなかったファーシェーダを試してみます。コードも書きやすいのでこれからはレガシーパイプラインではなく Universal Render Pipeline（URP）メインで書いていこうかな、と思っています（HDRP は直書きが大変すぎて趣味としては辛さが勝ったので余り触れない感じで. Ah, very good, thanks for the closure on this one. fx shader file uses some uniform parameters for a function: VSOutputTxEnvMap ComputeEnvMapVSOutput (VSInputNmTx vin, float3 normal,. The ability to specify the size of the. August 12, 2010 08:58 AM. 生成使用流控制执行循环的每个迭代的代码。 与 [unroll] 属性不兼容。 fastopt: 缩短编译时间，但生成较少主动的优化。 如果使用此属性，编译器将不会展开循环。 此属性仅影响支持 中断 指令的着色器模型目标。aah yes, you're right, webgl is quite limited there. Hi, how do I manage to compile the shaders on Ubuntu linux. Unrolling is generally. 따라서 hlsl을 배우시면 다른 쉐이더 언어를 익히시는데도 큰 무리가 없을 것입니다. The following information only applies to. Solution which worked was to compute number of samples on CPU and send it to the shader and use this variable as (for) loop boundary. 2 and HLSL. New subject: [PATCH v8 1/1] vkd3d-shader/hlsl: Ignore "unroll" attribute for loops. Problem was solved, it was a simple coding mistake, I needed to increase mip level on each iteration, not decrease it. I try adjustments and recompile one shader but that seems to recompile ALL shaders making. We start by implementing that in 2d. Incident update and uptime reporting. 正确地使用好这两个指令能够增强算法地并行性，提升吞吐量，降低延迟但是需要遵循一定的代码风格。. Like. This means that it has to unroll your loop to support the code you wrote. This must done for compatibility with HLSL shaders and also proper vertex assembly creation in D3D application. August 12, 2010 08:58 AM. シェーダープロパティでピクセル単位で幅を指定できるようにしました。. View all page feedback. If you used say tex2dlod (or a texture reading funciton that accepts the ddx and ddy parameters) it would be able to use a real loop. Log In to HSL. 3. HLSL code (on the GPU) is not like C code on the CPU. We don't want to have to do this level of analysis in Naga. TLDR: use the attribute [branch] in front of your if-statement. You should be using tex2Dgrad or tex2Dlod inside a loop. Creates a linker interface. With the new Unroll. In short: You can't return an array of floats defined in the function in HLSL. Doing so may require special handling of certain matrix operations: ; Indexing: no special handling. I understand that the problem is accessing the array in the loop. 8. 0 don't handle dynamic loop lengths well, so unrolled loops are generally better / faster and the compiler will try to unroll most of the time. It basically depends on hardware and on the driver, so different hardware or different driver versions might in the end determine a different execution from what you specified with the tag. Compile the statement as a series of if statements, each with the flatten attribute. Shader has ~700 lines, which are compiled into ~3000 instructions. The regular for loops does also give different results from the unrolled version of the same loop, even on the same local computer. It is executed concurrently on many GPU cores. Supported. A Unity ID allows you to buy and/or subscribe to Unity products and services, shop in the Asset Store and participate in the Unity community. See also. hlsl -spirv -enable-16bit-types says dxc failed : enable-16bit-types is only allowed for shader model >= 6. Reduces the compile time but produces less aggressive optimizations. Posts: 198. January 19, 2009 10:59 PM. Well you have a few options: -Use a loop/ifs like you have. 0 and all shader types (vertex, pixel, geometry, hull, domain, and compute). Unfortunately, the [loop] attribute isn’t completely foolproof. Hue — the color type such as red, blue, or. 前回の記事でジオメトリシェーダーでの頂点分割を試みました。. The shader assembly now has the ability to jump/branch to a new statement of execution, which is noticeable in the compiled code. 2. 1f ? -1:1 ); Type Description. // vertex #version 450 #extension GL_ARB_separate_shader_objects : enable out gl_PerVertex. If you're stuck with DX9 then your only alternative is to store your lighting parameters in a texture. flatten. 0 and 3. Zebediah Figura (＠zfigura) Release for 1. Low fps on Arm Mali GPU. これに指定された幅の値を掛けると、太さ分に該当する重. The [fastopt] and [allow_uav_condition] attributes are ignored if [unroll] is specified. h","path":"MSAAFilter/AppPCH. The compiler simulates loops by default to evaluate whether it can unroll them. Late response to this, but all I can suggest is leveraging the per-component math of HLSL better in your shaders. 8. If you comment out the blendedBiome [biome] line you should find it compiles fine. The above code forces the loop to unroll and gives the following warning: warning X3550: array reference cannot be used as an l-value; not natively addressable, forcing loop to unroll. Compilation time is with fxc (Windows 8 SDK) about 90 seconds. 12f1, and URP 10. Share. Use [unroll(n)] to give an explicit count. Shader Model. Thanks!HLSL也支持for, while和do while循环。和条件语句一样，它可能也会在基于运行时的条件值判断而产生动态分支，从而影响程序性能。如果循环次数较小，我们可以使用属性[unroll]来展开循环，代价是产生更多的汇编指令。用法如下：I am working on a Direct3D rendering application that uses a lot of texture RAM. basic recursive-decent language grammar: declarations, expressions, statements, loops, if-else, functions. sponsored post. Defines the number of threads to be executed in a single thread group when a compute shader is dispatched (see ID3D11DeviceContext::Dispatch ). This function is supported in the following shader models. You need to declare blurLength as a static int for this to work. Note This function is part of the HLSL shader linking technology that you can use on all Direct3D 11 platforms to create precompiled HLSL functions, package them into libraries, and link them into full shaders at run time. Remarks. That means the compiler will have to create a copy of the body of the loop for each iteration so that there is. . hlsl', which I can see is there in the. Stop executing the current loop ( do, for, while ), update the loop conditions, and begin executing from the top of the loop. branch, flatten -> if statement. To enable HLSL 2021, add the flag -HV. Direct3D High-level shader language (HLSL) Article 08/04/2021 4 contributors Feedback HLSL is the C-like high-level shader language that you use with. Furthermore, to really match the behavior people expect when generating GLSL/SPIR-V we may also need to detect loops that require unrolling (even if the user hasn't added the [unroll] atribute). So you can now do this: template<int iStartPlane, int iEndPlane> bool FrustumCull_Box (float3 BoxOrigin) { [unroll] for (uint PlaneIndex = iStartPlane; PlaneIndex < iEndPlane; ++PlaneIndex) { float4 PlaneData. Might be cheaper than an if, might not. This can improve performance. Sorry. {"payload":{"allShortcutsEnabled":false,"fileTree":{"tools/clang/test/HLSLFileCheck/hlsl/control_flow/attributes/unroll":{"items":[{"name":"2d_array. This is actually not fully correct. I quote DenisR's 2008 post on the NVidia forums: By default, the compiler unrolls small loops with a known trip count. Learn more about Teams If you unroll the loop by a factor of 1000 (ie 1000 threads), HLS will recognise that it can't read and write 1000 RAM elements at once and instead it'll build a large state machine to allow each thread to access the RAM (one at a time). A flow-control statement determines at run time which block of HLSL statements to execute next. to bool. Can somebody help me with it? Update: I think I found HLSL code with that errors but still don’t know how to fix it: Explanation. } Here, it's possible for the compiler to prove that the count can't be more than 4, so it would be safe to unroll the loop 4x, with. At a texel, the distance value is obtained from the alpha channel of the cube map.