How can I repeat my texture in DX - directx

Question

There is a handy feature in three.js 3d library that you can set the sampler to repeat mode and set the repeat attribute to some values you like, for example, (3, 5) means this texture will repeat 3 times horizontally and 5 times vertically. But now I'm using DirectX and I cannot find some good solutions for this problem. Note that the UV coordinates of vertices still ranges from 0 to 1, and I don't want to change my HLSL codes because I want a programmable solution for this, thanks very much!
Edit : presume I have a cube model already. And the texture coordinates of its vertices are between0 and 1. If i use wrap mode or clamp mode for sampling textures it's all OK now. But I want to repeat a texture on one of its faces, and I first need to change to wrap mode. That's i already knows. Then I have to edit my model so that texture coordinates range 0-3. What if I don't change my model? So far i came out one way: I need to add a variable to pixel shader represents how many times does the map repeats and I will multiply this factor to coordinate when sampling. Not a graceful solution i think emmmm…

Answer 1

Since you've edited your Question, there is another Answer to your problem:
From what I understood, you have a face with uv's like so:
0,1 1,1
-------------
| |
| |
| |
-------------
0,0 1,0
But want the texture repeated 3 times (for example) instead of 1 time.
(Without changing the original model)
Multiple solutions here:
You could do it, when updating your buffers (if you do it):
D3D11_MAPPED_SUBRESOURCE resource;
HRESULT hResult = D3DDeviceContext->Map(vertexBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &resource);
if(hResult != S_OK) return false;
YourVertexFormat *ptr=(YourVertexFormat*)resource.pData;
for(int i=0;i<vertexCount;i++)
{
ptr[i] = vertices[i];
ptr[i].uv.x *= multiplyX; //in your case 3
ptr[i].uv.y *= multiplyY; //in your case 5
}
D3DDeviceContext->Unmap(vertexBuffer, 0);
But if you don't need updating the buffer anyways, i wouldn't recommend it, because it is terribly slow.
A faster way is to use the vertex shader:
cbuffer MatrixBuffer
{
matrix worldMatrix;
matrix viewMatrix;
matrix projectionMatrix;
};
struct VertexInputType
{
float4 position : POSITION0;
float2 uv : TEXCOORD0;
// ...
};
struct PixelInputType
{
float4 position : SV_POSITION;
float2 uv : TEXCOORD0;
// ...
};
PixelInputType main(VertexInputType input)
{
input.position.w = 1.0f;
PixelInputType output;
output.position = mul(input.position, worldMatrix);
output.position = mul(output.position, viewMatrix);
output.position = mul(output.position, projectionMatrix);
This is what you basicly need:
output.uv = input.uv * 3; // 3x3
Or more advanced:
output.uv = float2(input.u * 3, input.v * 5);
// ...
return output;
}
I would recommend the vertex shader solution, because it's fast and in directx you use vertex shaders anyways, so it's not as expensive as the buffer update solution...
Hope that helped solving your problems :)

Answer 2

You basicly want to create a sampler state like so:
ID3D11SamplerState* m_sampleState;
3D11_SAMPLER_DESC samplerDesc;
samplerDesc.Filter = D3D11_FILTER_MIN_MAG_MIP_LINEAR;
samplerDesc.AddressU = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.AddressV = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.AddressW = D3D11_TEXTURE_ADDRESS_WRAP;
samplerDesc.MipLODBias = 0.0f;
samplerDesc.MaxAnisotropy = 1;
samplerDesc.ComparisonFunc = D3D11_COMPARISON_ALWAYS;
samplerDesc.BorderColor[0] = 0;
samplerDesc.BorderColor[1] = 0;
samplerDesc.BorderColor[2] = 0;
samplerDesc.BorderColor[3] = 0;
samplerDesc.MinLOD = 0;
samplerDesc.MaxLOD = D3D11_FLOAT32_MAX;
// Create the texture sampler state.
result = ifDEVICE->ifDX11->getD3DDevice()->CreateSamplerState(&samplerDesc, &m_sampleState);
And when you are setting your shader constants, call this:
ifDEVICE->ifDX11->getD3DDeviceContext()->PSSetSamplers(0, 1, &m_sampleState);
Then you can write your pixel shaders like this:
Texture2D Texture;
SamplerState SampleType;
...
float4 main(PixelInputType input) : SV_TARGET
{
float4 textureColor = shaderTexture.Sample(SampleType, input.uv);
...
}
Hope that helps...