• Advertisement
  • Popular Tags

  • Popular Now

  • Advertisement
  • Similar Content

    • By Jiraya
      For a 2D game, does using a float2 for position increases performance in any way?
      I know that in the end the vertex shader will have to return a float4 anyway, but does using a float2 decreases the amount of data that will have to be sent from the CPU to the GPU?
    • By ucfchuck
      I am feeding in 16 bit unsigned integer data to process in a compute shader and i need to get a standard deviation.
      So I read in a series of samples and push them into float arrays
      float vals1[9], vals2[9], vals3[9], vals4[9]; int x = 0,y=0; for ( x = 0; x < 3; x++) { for (y = 0; y < 3; y++) { vals1[3 * x + y] = (float) (asuint(Input1[threadID.xy + int2(x - 1, y - 1)].x)); vals2[3 * x + y] = (float) (asuint(Input2[threadID.xy + int2(x - 1, y - 1)].x)); vals3[3 * x + y] = (float) (asuint(Input3[threadID.xy + int2(x - 1, y - 1)].x)); vals4[3 * x + y] = (float) (asuint(Input4[threadID.xy + int2(x - 1, y - 1)].x)); } } I can send these values out directly and the data is as expected

      Output1[threadID.xy] = (uint) (vals1[4] ); Output2[threadID.xy] = (uint) (vals2[4] ); Output3[threadID.xy] = (uint) (vals3[4] ); Output4[threadID.xy] = (uint) (vals4[4] ); however if i do anything to that data it is destroyed.
      If i add a
      vals1[4] = vals1[4]/2; 
      or a
      vals1[4] = vals[1]-vals[4];
      the data is gone and everything comes back 0.
      How does one go about converting a uint to a float and performing operations on it and then converting back to a rounded uint?
    • By fs1
      I have been trying to see how the ID3DInclude, and how its methods Open and Close work.
      I would like to add a custom path for the D3DCompile function to search for some of my includes.
      I have not found any working example. Could someone point me on how to implement these functions? I would like D3DCompile to look at a custom C:\Folder path for some of the include files.
    • By stale
      I'm continuing to learn more about terrain rendering, and so far I've managed to load in a heightmap and render it as a tessellated wireframe (following Frank Luna's DX11 book). However, I'm getting some really weird behavior where a large section of the wireframe is being rendered with a yellow color, even though my pixel shader is hard coded to output white. 

      The parts of the mesh that are discolored changes as well, as pictured below (mesh is being clipped by far plane).

      Here is my pixel shader. As mentioned, I simply hard code it to output white:
      float PS(DOUT pin) : SV_Target { return float4(1.0f, 1.0f, 1.0f, 1.0f); } I'm completely lost on what could be causing this, so any help in the right direction would be greatly appreciated. If I can help by providing more information please let me know.
    • By evelyn4you
      i try to implement voxel cone tracing in my game engine.
      I have read many publications about this, but some crucial portions are still not clear to me.
      At first step i try to emplement the easiest "poor mans" method
      a.  my test scene "Sponza Atrium" is voxelized completetly in a static voxel grid 128^3 ( structured buffer contains albedo)
      b. i dont care about "conservative rasterization" and dont use any sparse voxel access structure
      c. every voxel does have the same color for every side ( top, bottom, front .. )
      d.  one directional light injects light to the voxels ( another stuctured buffer )
      I will try to say what i think is correct ( please correct me )
      GI lighting a given vertecie  in a ideal method
      A.  we would shoot many ( e.g. 1000 ) rays in the half hemisphere which is oriented according to the normal of that vertecie
      B.  we would take into account every occluder ( which is very much work load) and sample the color from the hit point.
      C. according to the angle between ray and the vertecie normal we would weigth ( cosin ) the color and sum up all samples and devide by the count of rays
      Voxel GI lighting
      In priciple we want to do the same thing with our voxel structure.
      Even if we would know where the correct hit points of the vertecie are we would have the task to calculate the weighted sum of many voxels.
      Saving time for weighted summing up of colors of each voxel
      To save the time for weighted summing up of colors of each voxel we build bricks or clusters.
      Every 8 neigbour voxels make a "cluster voxel" of level 1, ( this is done recursively for many levels ).
      The color of a side of a "cluster voxel" is the average of the colors of the four containing voxels sides with the same orientation.

      After having done this we can sample the far away parts just by sampling the coresponding "cluster voxel with the coresponding level" and get the summed up color.
      Actually this process is done be mip mapping a texture that contains the colors of the voxels which places the color of the neighbouring voxels also near by in the texture.
      Cone tracing, howto ??
      Here my understanding is confus ?? How is the voxel structure efficiently traced.
      I simply cannot understand how the occlusion problem is fastly solved so that we know which single voxel or "cluster voxel" of which level we have to sample.
      Supposed,  i am in a dark room that is filled with many boxes of different kind of sizes an i have a pocket lamp e.g. with a pyramid formed light cone
      - i would see some single voxels near or far
      - i would also see many different kind of boxes "clustered voxels" of different sizes which are partly occluded
      How do i make a weighted sum of this ligting area ??
      e.g. if i want to sample a "clustered voxel level 4" i have to take into account how much per cent of the area of this "clustered voxel" is occluded.
      Please be patient with me, i really try to understand but maybe i need some more explanation than others
      best regards evelyn
  • Advertisement
  • Advertisement
Sign in to follow this  

DX11 Geometry shader issue (linestrip)

This topic is 826 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi all,

I've managed to get a geometry shader working, with a vertex as input, outputting a cube in a trianglestream



As a next step/ practice, I've tried to change my code/ approach to achieve the following (book exercise):

- input: linestrip of vertices

- output: a cylinder going upwards, from the viewpoint of the linestrip

(people who worked through Luna's d3d11 book might recognize the exercise)


I think I did what I should, but I don't get any visible results.

The vertices going into the vtx buffer look OK (debugged).


Any idea what I'm doing wrong?

struct GeoOut
	float4 PosH    : SV_POSITION;
    float3 PosW    : POSITION;
    float3 NormalW : NORMAL;
    float2 Tex     : TEXCOORD;

// geometry shader for linestrip as input (cylinder, exercise 1)
void GSStrip(line VertexOut gin[2], inout LineStream<GeoOut> stream)
	float4 v[2];
	float4 b[1];

	v[0] = float4(gin[0].CenterW.xyz, 1.0f);
	v[1] = float4(gin[1].CenterW.xyz, 1.0f);

	const float StripWidth = 0.5f;
	float2 dir = normalize(v[1].xy - v[0].xy);
	float4 off = float4(-dir.y, dir.x, 0, 0);
	GeoOut gout;
	// only to prevent not completely initialized (UV's and normals not needed)
	gout.Tex = float2(0.0f, 1.0f);
	gout.NormalW = float3(1.0f, 0.0f, 0.0f);

	// 2 vertices at a time to create 2 triangles out of the quad (between non existing top/ bottom caps)
	gout.PosW	=    (v[0]-off*5).xyz;
	gout.PosH	= mul(v[0]-off*5, gViewProj);

	gout.PosW	=    (v[0]+off*5).xyz;
	gout.PosH	= mul(v[0]+off*5, gViewProj);

	gout.PosW	=    (v[1]-off*5).xyz;
	gout.PosH	= mul(v[1]-off*5, gViewProj);


	gout.PosW	=    (v[0]-off*5).xyz;
	gout.PosH	= mul(v[0]-off*5, gViewProj);

	gout.PosW	=    (v[1]-off*5).xyz;
    gout.PosH	= mul(v[1]-off*5, gViewProj);

	gout.PosW	=    (v[0]+off*5).xyz;
	gout.PosH	= mul(v[0]+off*5, gViewProj);

	gout.PosW	=    (v[1]+off*5).xyz;
	gout.PosH	= mul(v[1]+off*5, gViewProj);

// the application code (relevant parts)

void CircleGShaderApp::DrawScene()
	md3dImmediateContext->ClearRenderTargetView(mRenderTargetView, reinterpret_cast<const float*>(&Colors::Silver));
	md3dImmediateContext->ClearDepthStencilView(mDepthStencilView, D3D11_CLEAR_DEPTH|D3D11_CLEAR_STENCIL, 1.0f, 0);
	float blendFactor[] = {0.0f, 0.0f, 0.0f, 0.0f};
	XMMATRIX view  = XMLoadFloat4x4(&mView);
	XMMATRIX proj  = XMLoadFloat4x4(&mProj);
	XMMATRIX viewProj = view*proj;

	// draw cube and/or circle

	HR(mSwapChain->Present(0, 0));

void CircleGShaderApp::DrawCircle(CXMMATRIX viewProj)
	Effects::mTreeSpriteFX->SetDiffuseMap( mCircleMapSRV);


	UINT stride = sizeof(Vertex::TreePointSprite);
    UINT offset = 0;

	ID3DX11EffectTechnique* circleTech = Effects::mTreeSpriteFX->mLight3Tech;
		case RenderOptions::Lighting:
			circleTech = Effects::mTreeSpriteFX->mLight3Tech;

		case RenderOptions::Textures:
			circleTech = Effects::mTreeSpriteFX->mLight3TexAlphaClipTech;

		case RenderOptions::TexturesAndFog:
			circleTech = Effects::mTreeSpriteFX->mLight3TexAlphaClipFogTech;

	for(UINT p=0;p<techDesc.Passes;++p)
		md3dImmediateContext->IASetVertexBuffers(0, 1, &mCircleVtxBuffer, &stride, &offset);

		circleTech->GetPassByIndex(p)->Apply(0, md3dImmediateContext);
		md3dImmediateContext->Draw(NUM_VERTS, 0);

void CircleGShaderApp::BuildCircleGeometryBuffer()
	const UINT numSlices = 32;

	const UINT numCircleVerts = 33;
	float dTheta = 2.0f * XM_PI/numSlices;

	Vertex::TreePointSprite vertices[numCircleVerts];

	for(UINT i=0;i<numCircleVerts;++i)
		float x = 5*cosf(i*dTheta);
		float z = 5*sinf(i*dTheta);

		vertices[i].Pos    = XMFLOAT3(x, 0.0f, z);
    vbd.Usage = D3D11_USAGE_IMMUTABLE;
	vbd.ByteWidth = sizeof(Vertex::TreePointSprite) * numCircleVerts;
    vbd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
    vbd.CPUAccessFlags = 0;
    vbd.MiscFlags = 0;
    D3D11_SUBRESOURCE_DATA vinitData;
    vinitData.pSysMem = vertices;
    HR(md3dDevice->CreateBuffer(&vbd, &vinitData, &mCircleVtxBuffer));
Edited by cozzie

Share this post

Link to post
Share on other sites

I think that when you've done a RestartStrip() you need to supply 3+ vertices before next RestartStrip(), or you'll be outputting 2 vertices which won't form a triangle..?

Share this post

Link to post
Share on other sites
Clear, so that makes the solution in the link above incorrect or incomplete.

I'll dig into it to align the theory with the code. Not sure how yet, any suggestions are welcome (stil quite new to GS's, besides my cube experiment)

Share this post

Link to post
Share on other sites
Sign in to follow this  

  • Advertisement