• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Migi0027

DX11
DX11 Shader Generation

3 posts in this topic

This is just a question of curiosity by the way. wink.png

 

So some few weeks ago I was curious on how to render an object multiple times with different to archive different results, and the only problem is that if I try to use additive blending, I get a black object.  Now to the point,  because of this, a guy said to me:

 

"You could also just write a single shader that performs the appropriate computations for the diffuse term, direction lighting term, and reads the color from the read and modulates it by the lighting terms."

 

Now this is a good idea, but i wanted to give my engine the freedom to render any shaders together (render 1, render 2, etc...), and by that it would be easier! But he is right...

 

So I though, why not generate a shader, like:

String Diff  = "color = somecolor"
String Light = "...color += something..."

PixelShader += Diff;
PixelShader += Light;

WholeShader = Buffers + Layout + Vertex + Pixel;

Compile WholeShader

Now could something like this be made, due to flexibility, and is this how real material editors work? (E.g. UDK Material Editor)

 

Thank You

0

Share this post


Link to post
Share on other sites

Yes, that is the basic idea behind node-based shader editors like the one in UDK. Once you start implementing it though I think you'll find that it can get pretty hairy, due to complex interactions between the various features that you support. Personally I think it's easier (and better overall) to go with an ubershader approach where you just turn features on and off.

0

Share this post


Link to post
Share on other sites

Yes, that is the basic idea behind node-based shader editors like the one in UDK. Once you start implementing it though I think you'll find that it can get pretty hairy, due to complex interactions between the various features that you support. Personally I think it's easier (and better overall) to go with an ubershader approach where you just turn features on and off.

 

How exacly does this ubershader work(I've heard of it, but never wen't into it)? Is it a framework?

0

Share this post


Link to post
Share on other sites

"Ubershader" is just a name for a general pattern for authoring shader permutations. Typically you will write one large vertex and pixel shader with all possible features implemented, and then you will wrap the corresponding code for a certain features in "#ifdef" preprocessor statements. This allows you to compile different permutations of your shader with various features enabled or disabled by passing different macro definitions when compiling the shader. Here's a really simple example:

 

 

#ifdef ENABLE_COLOR_TEXTURE
Texture2D ColorTexture;
SamplerSTate ColorTextureSampler;
#endif

struct PSInput
{
    float4 VertexColor : VTXCOLOR;

#ifdef ENABLE_COLOR_TEXTURE
    float2 UV          : UV0;
#endif
};

float4 PSMain(in PSInput input) : SV_Target0
{
    float4 color = input.VertexColor;

#ifdef ENABLE_COLOR_TEXTURE
    color *= ColorTexture.Sample(ColorTextureSampler, input.UV);
#endif

    return color;
}


This is pixel shader for an ubershader that has 2 permutations: one with a color texture enabled, and one without. So you would compile one where you'd specify that you want ENABLE_COLOR_TEXTURE defined as an extra preprocessor macro, and one where you wouldn't. Then you can switch between the two at runtime depending on what you need for a particular mesh. Or alternatively you can have your features be options when authoring a material, and then you can specifically compile a shader permutation for that material. Typically you'll have lots of options that you want to disable, such as lighting, normal mapping, skinning, etc. Supporting all possible permutations of a bunch of on/off options then requires you to compile 2^N shaders, where N is the number of options you want to support. A common way index into all of these shaders is with a bitfield, where each the value of each bit corresponds to a feature being turned on or off. This gives you a simple hash that you can use to lookup into std::map or a similar data structure.

You can also support enabling or disabling features by wrapping them in regular if statements, and passing a bool through a constant buffer to specify whether you want them on or off. This saves you from having to compile different shaders and switch between them at runtime, which can save you build time and can also potentially save you some CPU time due to driver overhead from switching shaders. However in generally it will result in less optimal compiled shader code, since the compiler will be unable to fully optimize out the code in a branch that's not taken (or any code that produces results required for the branch not taken). This can result in extra instructions being executed, and potentially higher register usage which reduces thread occupancy. There's also some cost to actually executing a branch instruction, although this is generally small on modern DX11-capable hardware. The one major limitation of branches is that you can't use them to disable vertex shader inputs. Here's a simple example showing what I mean:

 

cbuffer VSConstants
{
    float4x4 World;
    float4x4 WorldViewProj;
}

#ifdef ENABLE_SKINNING
static const uint MaxBones = 256;

cbuffer SkinningConstants
{
    float4x4 Bones[MaxBones];
}

struct VSInput
{
    float3 Position : POSITION;
    float3 Normal : NORMAL;

#ifdef ENABLE_SKINNING
    uint4 SkinIndices : SKININDICES;
    float4 SkinWeights : SKINWEIGHTS;
#endif
};

struct VSOutput
{
    float4 Position : SV_Position;
    float3 Normal : NORMAL;
};

VSOutput VSMain(in VSInput input)
{
    VSOutput output;

#ifdef ENABLE_SKINNING
    float3 position = 0.0f;
    float3 normal = 0.0f;

    [unroll]
    for(uint i = 0; i < 4; ++i)
    {
        float4x4 bone = Bones[input.SkinIndices[i]];
        float weight = input.SkinWeights[i];
        position += mul(float4(input.Position, 1.0f), bone).xyz * weight;
        normal = mul(float4(normal, 0.0f), bone).xyz * weight;
    }
#else
    float3 position = input.Position;
    float3 normal = input.Normal;
#endif

    output.Position = mul(float4(position, 1.0f), WorldViewProj).xyz;
    output.Normal = mul(float4(normal, 0.0f), World).xyz;

    return output;
}


If you were to try to implement this feature using runtime branching instead of preprocessor macros, you'd have the problem that you wouldn't be able to disable the SkinWeights and SkinIndices vertex inputs. This means that even when skinning is disabled the shader would still expect those elements to be provided in a vertex buffer, so you'd either need to pad out your vertex buffers or pass dummy vertex buffers as a separate stream. It also means that the shader will expect the "Bones" constant buffer to be bound, which means you'll get spammed with warnings from the debug device (although the shader will still work fine as long as you don't actually use anything from that constant buffer). Edited by MJP
1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0

  • Similar Content

    • By YixunLiu
      Hi,
      I have a surface mesh and I want to use a cone to cut a hole on the surface mesh.
      Anybody know a fast method to calculate the intersected boundary of these two geometries?
       
      Thanks.
       
      YL
       
    • By hiya83
      Hi, I tried searching for this but either I failed or couldn't find anything. I know there's D11/D12 interop and there are extensions for GL/D11 (though not very efficient). I was wondering if there's any Vulkan/D11 or Vulkan/D12 interop?
      Thanks!
    • By lonewolff
      Hi Guys,
      I am just wondering if it is possible to acquire the address of the backbuffer if an API (based on DX11) only exposes the 'device' and 'context' pointers?
      Any advice would be greatly appreciated
    • By MarcusAseth
      bool InitDirect3D::Init() { if (!D3DApp::Init()) { return false; } //Additional Initialization //Disable Alt+Enter Fullscreen Toggle shortkey IDXGIFactory* factory; CreateDXGIFactory(__uuidof(IDXGIFactory), reinterpret_cast<void**>(&factory)); factory->MakeWindowAssociation(mhWindow, DXGI_MWA_NO_WINDOW_CHANGES); factory->Release(); return true; }  
      As stated on the title and displayed on the code above, regardless of it Alt+Enter still takes effect...
      I recall something from the book during the swapChain creation, where in order to create it one has to use the same factory used to create the ID3D11Device, therefore I tested and indeed using that same factory indeed it work.
      How is that one particular factory related to my window and how come the MakeWindowAssociation won't take effect with a newly created factory?
      Also what's even the point of being able to create this Factories if they won't work,?(except from that one associated with the ID3D11Device) 
    • By ProfL
      Can anyone recommend a wrapper for Direct3D 11 that is similarly simple to use as SFML? I don't need all the image formats etc. BUT I want a simple way to open a window, allocate a texture, buffer, shader.
  • Popular Now