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[DX11] Constant buffer only updates a few variables?

4 posts in this topic


so im currently on tutorial 6 of the dx sdk (lightning), and im trying to adapt it to my little framework. problem is it seems that the constant buffer only updates a few variables (at least the world matrix) but doesnt update others. the problem is such that i've removed any lightning and i only want to output a solid color, and it still doesnt work. when i hard-code the color on the pixel shader it works, when i try to use a color from the constant buffer it doesnt work..

its even more weird because all my attempts at the previous tutorials worked just fine, even passing a color through the constant buffer worked fine.. but im tired of going through all my code and i cant seem to find anything wrong but it still outputs black (like the constant buffer color is == 0.0f).

ill try to post every relevant code

relevant structs:
// the normal vertex im using
struct NormalVertex
XMFLOAT3 Normal;

//my constant buffer:
struct ConstantBuffer
XMMATRIX Projection;

XMFLOAT4 lightDir[2];
XMFLOAT4 lightCol[2];

XMFLOAT4 outputColor;

at the setup of my cube i create the constant buffer with an empty ConstantBuffer struct:
//create constant buffer:
array <ConstantBuffer, 1> tmpCB = { ConstantBuffer() };
inst.CreateBuffer(D3DEngine::Constant, tmpCB, &constantBuffer);

//the CreateBuffer method:
template <typename T, size_t Size>
void CreateBuffer(BufferType bufferType, const std::array <T, Size>& source, ID3D11Buffer** bufferOut)

ZeroMemory(&bd, sizeof(bd));
bd.Usage = D3D11_USAGE_DEFAULT;
bd.ByteWidth = sizeof(T) * source.size();
bd.BindFlags = bufferType;
bd.CPUAccessFlags = 0;

ZeroMemory(&initData, sizeof(initData));
initData.pSysMem = source.data();

hr = device->CreateBuffer(&bd, &initData, bufferOut);
throw std::exception("ID3D11Device::CreateBuffer() -> Failed.");

and this worked just fine when i tried a simple 2d triangle

and my render function for the cube:
ConstantBuffer cb;
cb.world = world;
cb.view = view;
cb.projection = projection;
cb.outputColor = XMFLOAT4(1.0f, 0.0f, 0.0f, 1.0f);

inst.UpdateBuffer(constantBuffer, cb);
inst.DrawRenderData(36); //36 vertices

//the update buffer method:
template <typename T>
void UpdateBuffer(ID3D11Buffer* buffer, const T& source)
deviceContext->UpdateSubresource(buffer, 0, nullptr, &source, 0, 0);

i set all the buffers and shaders and etc to the deviceContext at the cube setup.

now my shader:
cbuffer ConstantBuffer : register(b0)
matrix World;
matrix View;
matrix Projection;
float4 lightDir[2];
float4 lightCol[2];
float4 outputColor;

struct VS_INPUT
float4 Pos : POSITION;
float3 Normal : NORMAL;

struct PS_INPUT
float4 Pos : SV_POSITION;
float3 Normal : NORMAL;

PS_INPUT output = (PS_INPUT)0;
output.Pos = mul(input.Pos, World);
output.Pos = mul(output.Pos, View);
output.Pos = mul(output.Pos, Projection);
output.Normal = mul(input.Normal, World);

return output;

float4 PS(PS_INPUT input) : SV_TARGET
return outputColor;

i KNOW it updates a few constantbuffer variables because i can rotate the cube, so at least the world matrix is being updated but it draws the cube black..
if on the pixel shader i do: return float4(1.0f, 0.0f, 0.0f, 1.0f); it works!

this is driving me mad, if anyone can throw a tip ill really appreciate it.

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Did you try to debug it with Pix and see what is store in your color. Edited by phantom
Removing massive unneeded quote of first post

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[quote name='BornToCode' timestamp='1324497341' post='4896280']
Did you try to debug it with Pix and see what is store in your color.
thanks for the answer.

yes i just debbuged it using PIX and it says that outputColor = float4(0.0f, 0.0f, 0.0f, 0.0f);
thats so weird because i dont even initialize it with that value let alone update the constant buffer with that value. i set it as (1.0f, 0.0f, 0.0f, 1.0f) but for some reason on the pixel shader its equal to 0 :\

EDIT: when i check the buffer on PIX it has the correct value! i've even recompiled with a different value and it shown on the buffer as correct.. but on the pixel shader it says the value is 0.

since the dx tutorial runs fine on my computer i dont think its a driver issue or something.. this is really frustrating.

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Let me take a guess : you haven't bound your constant buffer to pixel shader resources, only to the vertex shader resources.

You'll need to call PSSetConstantBuffers too on the same constant buffer.

Best regards!

[Edit] You should enable Direct3D debug output which would help you track these kind of issues

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[quote name='kauna' timestamp='1324502838' post='4896313']
Let me take a guess : you haven't bound your constant buffer to pixel shader resources, only to the vertex shader resources.

You'll need to call PSSetConstantBuffers too on the same constant buffer.

Best regards!

[Edit] You should enable Direct3D debug output which would help you track these kind of issues
that was it, that solved it!

i had debug on on the dx control panel but the "filter info" checkbox was checked so it didint output any info (corrected now).
thank you so much for your help!

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