I need to draw a sprite with alpha but I don't know how and I Googled it and found little if any useful information.

What exactly are you trying to do? If you're using the sprite batch AlphaBlend is turn on by default (or you can explicitly set it if you want like this ->   spriteBatch.Begin(SpriteBlendMode.AlphaBlend);).

Is there something that's not working for you? If you could describe in a little more detail what you're trying to achieve I'm sure we can get you pointed in the right direction.

I also am having a little confusion with alphas. I'm placing simple 3D geometry in the world and moving it around. I don't have any screen HUD things, yet I still need to do a spriteBatch.Begin() and End() in order for my 3D objects' alpha to work. I have nothing between the Begin() and End(), yet it still seems to do make the alphas work. Is there a setting I can change so I don't even need the sprite batch?

Captain G:

I also am having a little confusion with alphas. I'm placing simple 3D geometry in the world and moving it around. I don't have any screen HUD things, yet I still need to do a spriteBatch.Begin() and End() in order for my 3D objects' alpha to work. I have nothing between the Begin() and End(), yet it still seems to do make the alphas work. Is there a setting I can change so I don't even need the sprite batch?

GraphicsDevice.RenderState.AlphaBlendEnable = true;

That didn't seem to work, no matter where I put it.

My textures are currently embedded into the .FBX files exported from 3ds max, though eventually I'd like to have the textures be coupled to the models in the code so that I can use the same texture on different models to save on memory.

I'm sure it's apparent by now that I'm a noob at this, but any help anyone can offer is appreciated.

Captain G:

That didn't seem to work, no matter where I put it.

My textures are currently embedded into the .FBX files exported from 3ds max, though eventually I'd like to have the textures be coupled to the models in the code so that I can use the same texture on different models to save on memory.

I'm sure it's apparent by now that I'm a noob at this, but any help anyone can offer is appreciated.

Are you using BasicEffect to render your models? If so have you set the Alpha property on the mesh effect to some value less than 1.0f?

Maybe also try these settings:

                graphicsDevice.RenderState.AlphaBlendEnable = true;
                graphicsDevice.RenderState.AlphaBlendOperation = BlendFunction.Add;
                graphicsDevice.RenderState.SourceBlend = Blend.SourceAlpha;
                graphicsDevice.RenderState.DestinationBlend = Blend.DestinationAlpha;
                graphicsDevice.RenderState.SeparateAlphaBlendEnabled = false;

also try this (rather than Blend.DestinationAlpha):

                graphicsDevice.RenderState.DestinationBlend = Blend.InverseSourceAlpha;

you have to set the blendsource desc, like this and it will work. becaus you can't just tell dx10 to use alpha when it dosent know how to blend it!


ID3D10BlendState* g_pBlendStateNoBlend = NULL;

D3D10_BLEND_DESC BlendState;
ZeroMemory(&BlendState, sizeof(D3D10_BLEND_DESC));
BlendState.BlendEnable[0] = true;
BlendState.RenderTargetWriteMask[0] = D3D10_COLOR_WRITE_ENABLE_ALL;
BlendState.SrcBlend = D3D10_BLEND_SRC_ALPHA;
BlendState.DestBlend = D3D10_BLEND_INV_SRC_ALPHA;
BlendState.BlendOp = D3D10_BLEND_OP_ADD;
BlendState.SrcBlendAlpha = D3D10_BLEND_ZERO;
BlendState.DestBlendAlpha = D3D10_BLEND_ZERO;
BlendState.BlendOpAlpha = D3D10_BLEND_OP_ADD;
BlendState.AlphaToCoverageEnable = true;
g_pd3dDevice->CreateBlendState(&BlendState, &g_pBlendStateNoBlend);
float blendFactor[] = {0,0,0,0};
UINT sampleMask   = 0xffffffff;

g_pd3dDevice->OMSetBlendState(g_pBlendStateNoBlend, blendFactor, sampleMask);


i hope this helps!

Dude this is toatally simple. Just save it as a .png. It stores transparency.

that dosen't work if you haven't set the alpha blend state, since it still dosent know how to handle the alpha

Why would you not have the alpha blend state set?

it dosent know how to render the alpha pixel, wich means, render it black or render it with the thing it is overlapping.