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Leon84

3D ID3DXSprite not blending properly on a render target

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Hi,

I am simply trying to draw 1 texture with full alpha, and another texture on top of it with a variable alpha.

If i draw on the screen, it is perfectly fine, however, if i do it on a rendertarget, and the second texture has 0 alpha, it will overwrite the previous alpha and leave a transparent block.

I am really desperate being trying to find out why this happens for 3 hours now.

I have attached a picture describing the issue.

It feels like it overwrites completely whats behind and draw a new completely thing, ignoring whats previously on the texture.

Here is the code on render target:

No error checking for sake of simplicity.

void CUI::Init()
{
    pDxDevice->CreateTexture(mTexCompSubTierBG.iWidth, mTexCompSubTierBG.iHeight, 1, D3DUSAGE_RENDERTARGET, D3DFMT_A8R8G8B8, D3DPOOL_DEFAULT, &pTexRenderTarget, 0);
}

void CUI::PreRender()
{
    IDirect3DSurface9* ppSurface = NULL;
    if (pTexRenderTargetDData.pTex->GetSurfaceLevel(0, &ppSurface) == D3D_OK)
    {
        pDxDevice->SetRenderTarget(0, ppSurface);
        pDxDevice->SetDepthStencilSurface(NULL);

        pDxDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, D3DCOLOR_COLORVALUE(0.0f, 0.0f, 0.0, 0.0f), 1.0f, 0);

        pDxDevice->BeginScene();

        pSprite->Begin(D3DXSPRITE_ALPHABLEND);

        RECT mRect;
        CDxUtils::SetRectPlusSize(&mRect, mTexCompSubBG.iPosX, mTexCompSubBG.iPosY, mTexCompSubBG.iWidth, mTexCompSubBG.iHeight);
        pSprite->Draw(mTexCompSubBG.pTexData->pTex, &mRect, NULL, &D3DXVECTOR3(0, 0, 0), 0xFFFFFFFF);

        CDxUtils::SetRectPlusSize(&mRect, mTexCompRedeemBtn[1].iPosX, mTexCompRedeemBtn[1].iPosY, mTexCompRedeemBtn[1].iWidth, mTexCompRedeemBtn[1].iHeight);
        pSprite->Draw(mTexCompRedeemBtn[1].pTexData->pTex, &mRect, NULL, &D3DXVECTOR3(55, 240 + 2, 0), 0xFFFFFFFF);

        CDxUtils::SetRectPlusSize(&mRect, mTexCompRedeemBtn[0].iPosX, mTexCompRedeemBtn[0].iPosY, mTexCompRedeemBtn[0].iWidth, mTexCompRedeemBtn[0].iHeight); // Texture with FULL ALPHA
        pSprite->Draw(mTexCompRedeemBtn[0].pTexData->pTex, &mRect, NULL, &D3DXVECTOR3(55, 240 + 2, 0), 0x00FFFFFF); // Texture with 0 Alpha and now i have a transparent block, why does it not blend? Why is it fine if you draw on screen and not on rendertarget?
      
        pSprite->End();

        pDxDevice->EndScene();
    }
}

void CUI::Render()
{
    D3DXMATRIX mMat;
	D3DXVECTOR2 spriteCentre = D3DXVECTOR2(mTexCompSubTierBG.iWidth / 2, mTexCompSubTierBG.iHeight / 2);
	D3DXVECTOR2 trans = D3DXVECTOR2(fCurPos[0] - mTexCompSubTierBG.iWidth / 2, fCurPos[1] - mTexCompSubTierBG.iHeight / 2);
	D3DXVECTOR2 scaling(fCurScaleX, fCurScaleY);
	D3DXMatrixTransformation2D(&mMat, &spriteCentre, 0, &scaling, &spriteCentre, 0, &trans);

	pSprite->SetTransform(&mMat);
	pSprite->Draw(pTexRenderTargetDData.pTex, NULL, NULL, NULL, 0xFFFFFFFF);
	pSprite->SetTransform(&matIdentity);
}

 

Thank you so much in advance.

alpha50.png

Edited by Leon84

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