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# DX11 DX11 Sprite Like Technique - With a quad

## 9 posts in this topic

Hi guys,

right now I'm having a small quad with a texture on it, and I wan't it to face my camera. The reason for that is because I wan't to mess around with Post Processing, It looks for me right now:

if ssao

Render Normals to TEXTUREN

Render Position to TEXTUREP

Render Diffuse     to TEXTURED

Render Plane with TEXTUREN | TEXTUREP | TEXTURED - To do some post processing

Show it!

Now please correct me if this is a wrong way!

But how is it possible to rotate and translate a quad to face the player/camera, looking like it's a real 3d scene (with some post processing) ?

Thank You

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Though now I'm not sure if it's the right way...

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But how is it possible to rotate and translate a quad to face the player/camera, looking like it's a real 3d scene (with some post processing) ?

There are a number of ways to do a full screen quad.  Typically you just send four vertices with already transformed content (i.e. w=1 already) and their positions are in the clip space corners.  They would be something like this:

(-1,1,0,1) for upper left

(1,1,0,1) for upper right

(-1,-1,0,1) for lower left

(1,-1,0,1) for lower right

Since these are in clip space, you are guaranteed to cover the entire viewport regardless of the actual size of it.

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But how in terms of HLSL would this be possible?

So would i specify those 4 points and directly map them into HLSL, without any use of any Matrices? Sorry, I'm not very familiar with this topic of view space conversions...

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But how in terms of HLSL would this be possible?

So would i specify those 4 points and directly map them into HLSL, without any use of any Matrices? Sorry, I'm not very familiar with this topic of view space conversions...

Yup - that's exactly right.  The vertices are already ready to go to the rasterizer, so you just pass them through the vertex shader.  Just make sure your w-values are equal to 1, and it should work fairly easily.  To test it out, you can also try modifying the values to cover half the screen, a quarter of the screen, etc...

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Sorry to take your time, I do understand the concept, but I'm doing it wrong somehow.

#include "stdafx.h"
#include "PostProcess.h"

#include <d3dcompiler.h>
#include <DxErr.h>

#define CE_WARNING(title, message) MessageBoxA(NULL, message, title, 0)

BOOL PostProcessClass::Create( ID3D11Device *&dev, ID3D11DeviceContext *&devcon )
{
string finals = string(

ID3D10Blob *vserrors;
ID3D10Blob *pserrors;
HRESULT HR;

D3DX11CompileFromFile(finals.c_str(), 0, 0, "VShader", "vs_5_0", D3DCOMPILE_DEBUG, 0, 0, &VS, &vserrors, &HR);
D3DX11CompileFromFile(finals.c_str(), 0, 0, "PShader", "ps_5_0", D3DCOMPILE_DEBUG, 0, 0, &PS, &pserrors, &HR);

if (!VS)
{
DXTRACE_ERR(TEXT(DXGetErrorDescription(HR)),HR);

MessageBoxA(NULL, "The Post Process vertex shader creation has failed, program will now exit!", "ERROR", 0);
exit(0);
}
if (!PS)
{
DXTRACE_ERR(TEXT(DXGetErrorDescription(HR)),HR);

MessageBoxA(NULL, "The Post Process pixel shader creation has failed, program will now exit!", "ERROR", 0);
exit(0);
}

D3D11_INPUT_ELEMENT_DESC ied[] =
{
{"POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, D3D11_APPEND_ALIGNED_ELEMENT, D3D11_INPUT_PER_VERTEX_DATA, 0}
};

if (dev->CreateInputLayout(ied, 1, VS->GetBufferPointer(), VS->GetBufferSize(), &pLayout) != S_OK)
CE_WARNING("Input Layout Creation", "Input Layout creation in Post Process has failed!");

// create the vertex buffer
D3D11_BUFFER_DESC bd;
ZeroMemory(&bd, sizeof(bd));

Vertices[0] = D3DXVECTOR3(-1, 0, 1);
Vertices[1] = D3DXVECTOR3(1, 0, 1);
Vertices[2] = D3DXVECTOR3(-1, 0, -1);
Vertices[3] = D3DXVECTOR3(1, 0, 1);

Indices[0] = 3;
Indices[1] = 1;
Indices[2] = 2;
Indices[3] = 2;
Indices[4] = 1;
Indices[5] = 0;

bd.Usage = D3D11_USAGE_DYNAMIC;
bd.ByteWidth = sizeof(D3DXVECTOR3) * 4;
bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
bd.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;

dev->CreateBuffer(&bd, NULL, &vBFF);

D3D11_MAPPED_SUBRESOURCE ms;
// copy the vertices into the buffer
devcon->Map(vBFF, NULL, D3D11_MAP_WRITE_DISCARD, NULL, &ms);    // map the buffer
memcpy(ms.pData, Vertices, sizeof(Vertices));                 // copy the data
devcon->Unmap(vBFF, NULL);

//**INDICES**//

bd.Usage = D3D11_USAGE_DYNAMIC;
bd.ByteWidth = sizeof(DWORD) * 6;
bd.BindFlags = D3D11_BIND_INDEX_BUFFER;
bd.CPUAccessFlags = D3D11_CPU_ACCESS_WRITE;

dev->CreateBuffer(&bd, NULL, &iBFF);

D3D11_MAPPED_SUBRESOURCE msI;
// copy the vertices into the buffer
devcon->Map(iBFF, NULL, D3D11_MAP_WRITE_DISCARD, NULL, &msI);    // map the buffer
memcpy(msI.pData, Indices, sizeof(Indices));                 // copy the data
devcon->Unmap(iBFF, NULL);
}

{
devcon->IASetInputLayout(pLayout);
}

void PostProcessClass::Render(ID3D11DeviceContext *&devcon, ID3D11Device *&dev)
{

UINT stride = sizeof(D3DXVECTOR3);
UINT offset = 0;

devcon->IASetVertexBuffers(0, 1, &vBFF, &stride, &offset);
devcon->IASetIndexBuffer(iBFF, DXGI_FORMAT_R32_UINT, 0);

devcon->DrawIndexed(6, 0, 0);
}


Now the output is a black screen, and heres the reason from debugging:

When you look at the vertex shader, the result is a straight line, which isn't exactly what I wanted

Now the question is why?

Ohh, almost forgot, my shader (it's simple for now for debugging):

struct VOut
{
float4 position : SV_POSITION;
};

{
VOut output;

output.position = float4(position, 1.0f);
output.position.w = 1.0f;

return output;
}

{
return float4(1, 0, 0, 1);
}

Edited by Migi0027
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Between, should I even send an index buffer? For something as simple as this, is Direct3D capable of generating it itself?

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Note that what gets generated there isn't a quad, that's because using a single triangle makes things slightly more efficient in the pixel shader.

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Wait, so what should I do, I'm probably not understanding this then... What's wrong with my code?

Edited by Migi0027
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Ok, got it working using Adam_42's method, but thanks!

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