2D using Direct3D, some problems drawing sprites

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Original post by Magos
Ah, I found the problem. It seems like whena texture is read it converts it to the closest "power of 2" square dimension abov its current. If I had a 256 * 200 texture, it would be converted to a 256*256 meaning the bottom 56 pixels are gone when rendering. I believe the solution to this is to store the dimensions somewhere when loading the texture. Unless someone has a better solution.

Thanks for your help. I followed the tutorial on this site with quads, and they never mentioned an offset by 0.5. Hm...

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Original post by CrazyEddie
What you suggest is about right. I have a class that represents each texture (which contains a set of sprites) - I use D3DXCreateTextureFromFileEx to load the texture and get the dimensions from the D3DXIMAGE_INFO that it fills in, these are stored in data fields in the class and used later by the sprite drawing routines.

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Original post by glassJAw
you do NOT use an 0.5 bias for destination coordinates.

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From the SDK docs
...
Given an understanding of this mapping, you can apply a simple bias to your screen-space geometry coordinates to force the system to map each texel to a corresponding pixel. For example, to draw a four-sided polygon that maps each texel from the preceding texture to one, and only one, pixel on the screen, you must force geometry coordinates to overlap the pixels, effectively placing the center of each texel at the center of each pixel. The result is the 1-to-1 mapping often sought-after by applications.
...

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Original post by Magos
Another question. When I''m in the program, then Alt-Tabs out I cannot enter again. What is causing this?

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Original post by Magos
So you have to manually reload all textures again?

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Original post by Magos
It works better now. I forgot to fill in the parameters when calling the Reset() method :ashamed:
Anyway, when returning into the program everything is pitch black. Seems like the textures are unloaded, but I''ve been using the D3DPOOL_MANAGED when loading the textures.

I noticed the vertices I create are also placed in the managed pool (D3DPOOL_MANAGED), but you say they cannot? What do you mean by dynamic? I modify it in every call to DrawSprite.

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//Attempt to create a texture from a file

	if(FAILED(D3DXCreateTextureFromFileEx(Direct3DDevice, FileName, D3DX_DEFAULT, D3DX_DEFAULT, 1, 0, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED, D3DX_FILTER_NONE, D3DX_DEFAULT, TransparentColor, &ImageInfo, NULL, &TextureBuffer[Index])))
	{
		return FALSE;
	}

BOOL GRAPHICS::BeginRender()
{
	//Data

	HRESULT Result;

	//Checks if the program lost focus

	Result = Direct3DDevice->TestCooperativeLevel();
	if(Result != D3D_OK)
	{
		//If you cannot simply reset, wait until you can

		if(Result == D3DERR_DEVICELOST)
		{
			return FALSE;
		}

		//Resets the device

		Direct3DDevice->Reset(&PresentParameters);

		//Re-sets the render states

		SetupRenderStates();
	}

	//Clears the back buffer

	if(FAILED(Direct3DDevice->Clear(0, NULL, D3DCLEAR_TARGET, 0x00000000, 0, 0)))
	{
		return FALSE;
	}

	//Begins rendering

	if(FAILED(Direct3DDevice->BeginScene()))
	{
		return FALSE;
	}

	//Return success

	return TRUE;
}

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Original post by Magos
No, not black squares. They don''t show up at all.
And the only reason why my DrawSprite methods wouldn''t be called is if BeginRender (see above) returns FALSE. Which I highly doubt.

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//Sets the texture

	if(FAILED(Direct3DDevice->SetTexture(0, TextureBuffer[SpriteNr])))
	{
		return FALSE;
	}

	//Draws the sprite

	if(FAILED(Direct3DDevice->DrawPrimitive(D3DPT_TRIANGLEFAN, 0, 2)))
	{
		return FALSE;
	}

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Original post by CrazyEddie

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Original post by glassJAw
you do NOT use an 0.5 bias for destination coordinates.

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Ah, so the people who wrote the DirectX SDK documentation should have asked you about this then, instead of writing what they did about texel to pixel mapping and the need for a bias to ensure things always appear correct?

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From the SDK docs
...
Given an understanding of this mapping, you can apply a simple bias to your screen-space geometry coordinates to force the system to map each texel to a corresponding pixel. For example, to draw a four-sided polygon that maps each texel from the preceding texture to one, and only one, pixel on the screen, you must force geometry coordinates to overlap the pixels, effectively placing the center of each texel at the center of each pixel. The result is the 1-to-1 mapping often sought-after by applications.
...

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What are they talking about here then?

Also, in my own recent experience, I had a problem which was not even visible in all systems, but after re-reading the docs properly and understanding them, the solution became obvious. Applying the bias made the problem go away, along with the need for a messy kludge which I had to overcome another (obviously related) issue.

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Robert Dunlop (X-Zone) suggests that you expand your target rectangle "by 0.5 on all sides to allow proper mapping of texels to pixels." This will "compensate for the texel alignment rules of Direct3D" that are causing this problem [2, 3]

But it doesn't work.

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Interestingly, there's a very simple solution to this problem: extend the right and bottom sides of your sprite by 1 pixel.

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Maybe there's a logical explanation for it. Maybe they aren't referring to "pixel coordinates". The API documentation doesn't explicitly say this (but most people would interpret it that way).

Nevertheless, it does explain why extending the right and bottom of a sprite by 1 fixes the problem.

The DirectX 8 documentation for rectangles is wrong. You can find this page under DirectX Graphics:

* Introduction to DirectX Graphics
o Getting Started With DirectX Graphics
+ Rectangles

According to the documentation, the coordinates (right, bottom) refer to the bottom-right pixel of the rectangle. This is wrong. The coordinates (right, bottom) are actually 1-pixel outside the rectangle.

The documentation describes an inclusive-inclusive coordinate system. But DirectX uses inclusive-exclusive coordinates; the last pixel (right, bottom) is not part of the rectangle.

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Original post by Magos
Yes. I tested it and the DrawSprite methods are running. Not working though...

I did some more testing:

//Sets the texture

	if(FAILED(Direct3DDevice->SetTexture(0, TextureBuffer[SpriteNr])))
	{
		return FALSE;
	}

	//Draws the sprite

	if(FAILED(Direct3DDevice->DrawPrimitive(D3DPT_TRIANGLEFAN, 0, 2)))
	{
		return FALSE;
	}

That is the last part of my DrawSprite function. I found out that DrawPrimitive() returns D3DERR_INVALIDCALL after I''ve Alt-Tabbed out then in again.
That''s the error when an invalid parameter is passed, right? Well, I don''t understand how any of those parameters can be invalid... (D3DPT_TRIANGLEFAN, 0 or 2).

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