• 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
montify

DX11
Use 64bit precision (GPU)

10 posts in this topic

Hello,

 

I've bin working on a large Terrain, so now im on the Point that i reach the precision of float.

 

 

Im working with DX11 / ShaderModel 5 and this provided doubles on GPU..

 

 

My Question is: How i can use double (Matrix, inputPosition) instead of float?

 

 

I read something about Render relative to the Eye or so, but the simple solution should use doubles, but how?

 

 

 

 

 

0

Share this post


Link to post
Share on other sites


My Question is: How i can use double (Matrix, inputPosition) instead of float?

 

From MSDN HLSL Scalar Types: http://msdn.microsoft.com/en-us/library/windows/desktop/bb509646(v=vs.85).aspx

 

  • double - 64-bit floating point value. You cannot use double precision values as inputs and outputs for a stream. To pass double precision values between shaders, declare each double as a pair of uint data types. Then, use the asdouble function to pack each double into the pair of uints and the asuint function to unpack the pair of uints back into the double.

So I think you will have to encode the doubles into a pair of uint values to pass them around.

1

Share this post


Link to post
Share on other sites

If you want to render stuff relative to the eye in float space using doubles, you:

 

1. Use doubles for your position vectors.

2. Use the double vector for every object position, and for your camera.

 

Then you have to translate your positions into a float-capable space for rendering. You translate every object position to get the position relative to the eye with:



DoubleVector3 objectPosition = object.somePosition;
DoubleVector3 cameraPosition = camera.position;
DoubleVector3 doubleRelativePosition = objectPosition - cameraPosition;

// When you translate the object by the camera position, the resulting number is representable by a float.
// Just cast the double-vector components down to floats!

FloatVector3 relativePosition;
relativePosition.x = (float)doubleRelativePosition.x;
relativePosition.y = (float)doubleRelativePosition.y;
relativePosition.z = (float)doubleRelativePosition.z;

and then that's the position you pass into the shader for rendering.

 

This is really cumbersome for a ton of objects because you have to recompute this translation every time you move your camera. There is an extension of this method to keep you from creating relative coordinates every frame. You have to create a relative anchor point that moves with your camera. To do this you have to:

 

1. Create a double-vector anchor point that moves with your camera periodically. You move this anchor point when float-precision starts to become insufficient to represent points inside the float-anchor-area.
2. You build relative float-vector positions for everything relative to the anchor point, as we did before with the camera but with the anchor point.

3. When you move far enough away from the anchor, you re-locate it.

4. When the anchor moves you re-translate everything relative to the new anchor point. This means everything has a double-vector world position and a float-vector relative anchor position.

5. You use a regular camera view matrix to move around inside this anchor float space.
6. Draw everything normally as if the anchor-relative position is the position, and the anchor relative camera position is the camera location.

I hope this helps!

Edits: Typo-city

Edited by DementedCarrot
1

Share this post


Link to post
Share on other sites

You should probably consider whether or not lack of precision is really the issue you are facing. Modern GPUs may support DP floating point because of SM5, but it is a feature which is almost never used by anyone (for games anyway) so consumer GPUs tend to be really bad at it. Take my GPU for example, a GTX 760 which is probably pretty typical. Switching from SP floats to DP floats is the difference between 2.25 teraflops and 94 gigaflops. That's a huge performance decrease.

0

Share this post


Link to post
Share on other sites
Thank you for reply

Ok i should use relative to the eye

So i have one vertexbuffer for each childnode and rootnode.
Only the worldmatrix is changing.

My problem is i use cube2sphere mapping which require that the cubecenter is 0,0,0

With relative to the eye the camera position is at 0,0,0?
So whats my line? When i substract the camera position from the patch position the cube is out of the origin in worldspace
0

Share this post


Link to post
Share on other sites
My problem is i use cube2sphere mapping which require that the cubecenter is 0,0,0

 

Can you be more specific about what cube2sphere mapping is, and what it's used for?

0

Share this post


Link to post
Share on other sites

Oh Sorry, so :

 

Im working on a Procedural Planet with ChunkedLOD in earth Size.

 

To get a Sphere out of 6 Planes, i normalize each Vertex.

 

But the requirement is, the center of the cube (out of 6 planes) must be 0,0,0 (world-origin) like:

 

http://britonia.wordpress.com/2010/05/20/planet-geometry/

 

 

But here do the Vector3.normalize on the CPU, but i do it on the GPU:

VertexShaderOutput VertexShaderFunction(VertexShaderInput input)
{
    VertexShaderOutput output;

	
	float3 worldPosition = mul(input.Position, World).xyz;


		float3 normalized = normalize(worldPosition);
		float4 scaled = float4(normalized * SeaLevel, 1);

		output.Position = mul(mul(scaled, View), Projection);

		output.UV = input.UV;

    return output;
}

So, when i subtract the Camera Position from the QuadTree-Patch Position the Center of my Sphere/Cube is not 0,0,0 .

Edited by montify
0

Share this post


Link to post
Share on other sites

That's a tough one. I'm not totally sure how to accomplish this when the world meshes are created that way.

 

I'll think on it.

0

Share this post


Link to post
Share on other sites

nono the worldmesh created like:

 

 

I have one VertexBuffer 33x33 vertices. ( a flat Plane )

 

Now i made 6 of this Planet (Rotatet, Translate) to get a Cube.

 

Now i normalize the Input.Position in the Shader = A perfect Sphere.

 

---------------------

 

Is it possible and have it the same effect to translate the Position ( Position - cameraPosition) NOT in the WorldSpace but rather in ViewSpace?

0

Share this post


Link to post
Share on other sites

So i have it .

 

I Set the Camera Posititon to Vector3.Zero and "hack" the worldMatrix
 

  //new View Matrix
                var View = Matrix.CreateLookAt(Vector3.Zero, cam.Forward, cam.Up);


                Vector3 cameraSpacePosition = (position - cam.Position);

                //Relative to the Camera
                world.M41 = cameraSpacePosition.X;
                world.M42 = cameraSpacePosition.Y;
                world.M43 = cameraSpacePosition.Z;

But i scale/normalize each vertex (the entire Planet) in the Shader like ( with *6000):

VertexShaderOutput VertexShaderFunction(VertexShaderInput input)
{
    VertexShaderOutput output;

	float3 worldPosition = mul(input.Position, World).xyz;
	
	float3 normalized = normalize(worldPosition);
	float4 scaled = float4(worldPosition * 6000, 1);

	output.Position = mul(scaled, ViewProj);

	output.Position.z = log(C*output.Position.z + 1) / log(C*Far + 1) * output.Position.w; //Logarithmic Depth Buffer
	
    return output;
}

The Scale and Normalize don't work anymore...

 

anybody out there who have a Solution for this Problem?

Edited by montify
0

Share this post


Link to post
Share on other sites

Update:

 

Now i do the Relative to the Eye transformation in the VertexShader
 

VertexShaderOutput VertexShaderFunction(VertexShaderInput input)
{
    VertexShaderOutput output;

	float3 worldPosition = mul(input.Position, World).xyz;


		float3 normalized = normalize(worldPosition);  // Normalize all Vertex to get a Sphere

		float4 scaled = float4(normalized * SeaLevel, 1);  // Scale all Vertex with SeaLevel = 6000

		scaled -= float4(camPosition, 1); //All geometry relative to the Eye 
		

	output.Position = mul(scaled, ViewProj);
	output.Position.z = log(C*output.Position.z + 1) / log(C*Far + 1) * output.Position.w; //Logarithmic Depth Buffer
    return output;
}

It works, no Jittering, but i have some odd  "stairs"

 

So whats going on here?

treppen.png

0

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 lonewolff
      Hi Guys,
      I am revisiting an old DX11 framework I was creating a while back and am scratching my head with a small issue.
      I am trying to set the pixel shader resources and am getting the following error on every loop.
      As you can see in the below code, I am clearing out the shader resources as per the documentation. (Even going overboard and doing it both sides of the main PSSet call). But I just can't get rid of the error. Which results in the render target not being drawn.
      ID3D11ShaderResourceView* srv = { 0 }; d3dContext->PSSetShaderResources(0, 1, &srv); for (std::vector<RenderTarget>::iterator it = rtVector.begin(); it != rtVector.end(); ++it) { if (it->szName == name) { //std::cout << it->srv <<"\r\n"; d3dContext->PSSetShaderResources(0, 1, &it->srv); break; } } d3dContext->PSSetShaderResources(0, 1, &srv);  
      I am storing the RT's in a vector and setting them by name. I have tested the it->srv and am retrieving a valid pointer.
      At this stage I am out of ideas.
      Any help would be greatly appreciated
       
    • By bowerbirdcn
      hi, guys, how to understand the math used in CDXUTDirectionWidget ::UpdateLightDir 
      the  following code snippet is taken from MS DXTU source code
       
        D3DXMATRIX mInvView;
          D3DXMatrixInverse( &mInvView, NULL, &m_mView );
          mInvView._41 = mInvView._42 = mInvView._43 = 0;
          D3DXMATRIX mLastRotInv;
          D3DXMatrixInverse( &mLastRotInv, NULL, &m_mRotSnapshot );
          D3DXMATRIX mRot = *m_ArcBall.GetRotationMatrix();
          m_mRotSnapshot = mRot;
          // Accumulate the delta of the arcball's rotation in view space.
          // Note that per-frame delta rotations could be problematic over long periods of time.
          m_mRot *= m_mView * mLastRotInv * mRot * mInvView;
          // Since we're accumulating delta rotations, we need to orthonormalize 
          // the matrix to prevent eventual matrix skew
          D3DXVECTOR3* pXBasis = ( D3DXVECTOR3* )&m_mRot._11;
          D3DXVECTOR3* pYBasis = ( D3DXVECTOR3* )&m_mRot._21;
          D3DXVECTOR3* pZBasis = ( D3DXVECTOR3* )&m_mRot._31;
          D3DXVec3Normalize( pXBasis, pXBasis );
          D3DXVec3Cross( pYBasis, pZBasis, pXBasis );
          D3DXVec3Normalize( pYBasis, pYBasis );
          D3DXVec3Cross( pZBasis, pXBasis, pYBasis );
       
       
      https://github.com/Microsoft/DXUT/blob/master/Optional/DXUTcamera.cpp
    • 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
  • Popular Now