添加文本

DXUT框架對文本繪制進行了封裝，提供了類CDXUTHelper來簡化文本顯示，使用該接口大體分為3個步驟：初始化ID3DXSprite和ID3DXFont對象，顯示文本，釋放ID3DXSprite和ID3DXFont對象。

首先來看看CDXUTHelper的定義部分：

 

接著來看看CDXUTHelper的實現(xiàn)部分：

 

代碼相當(dāng)簡潔明了，需要說明的是函數(shù)StringCchVPrintf： 

以及ID3DXSprite::Begin()的聲明：

Prepares a device for drawing sprites.

HRESULT Begin(
  DWORD Flags
);

Parameters

Flags

[in] Combination of zero or more flags that describe sprite rendering options. For this method, the valid flags are:

• D3DXSPRITE_ALPHABLEND
• D3DXSprite__BILLBOARD
• D3DXSPRITE_DONOTMODIFY_RENDERSTATE
• D3DXSPRITE_DONOTSAVESTATE
• D3DXSPRITE_OBJECTSPACE
• D3DXSprite__SORT_DEPTH_BACKTOFRONT
• D3DXSprite__SORT_DEPTH_FRONTTOBACK
• D3DXSprite__SORT_TEXTURE

For a description of the flags and for information on how to control device state capture and device view transforms, see D3DXSPRITE.

Return Values

If the method succeeds, the return value is S_OK. If the method fails, the return value can be one of the following: D3DERR_INVALIDCALL, D3DERR_OUTOFVIDEOMEMORY, D3DXERR_INVALIDDATA, E_OUTOFMEMORY.

Remarks

This method must be called from inside a IDirect3DDevice9::BeginScene . . . IDirect3DDevice9::EndScene sequence. ID3DXSprite::Begin cannot be used as a substitute for either IDirect3DDevice9::BeginScene or ID3DXRenderToSurface::BeginScene.

This method will set the following states on the device.

Render States:

Type (D3DRENDERSTATETYPE)	Value
D3DRS_ALPHABLENDENABLE	TRUE
D3DRS_ALPHAFUNC	D3DCMP_GREATER
D3DRS_ALPHAREF	0x00
D3DRS_ALPHATESTENABLE	AlphaCmpCaps
D3DRS_BLENDOP	D3DBLENDOP_ADD
D3DRS_CLIPPING	TRUE
D3DRS_CLIPPLANEENABLE	FALSE
D3DRS_COLORWRITEENABLE	D3DCOLORWRITEENABLE_ALPHA | D3DCOLORWRITEENABLE_BLUE | D3DCOLORWRITEENABLE_GREEN | D3DCOLORWRITEENABLE_RED
D3DRS_CULLMODE	D3DCULL_NONE
D3DRS_DESTBLEND	D3DBLEND_INVSRCALPHA
D3DRS_DIFFUSEMATERIALSOURCE	D3DMCS_COLOR1
D3DRS_ENABLEADAPTIVETESSELLATION	FALSE
D3DRS_FILLMODE	D3DFILL_SOLID
D3DRS_FOGENABLE	FALSE
D3DRS_INDEXEDVERTEXBLENDENABLE	FALSE
D3DRS_LIGHTING	FALSE
D3DRS_RANGEFOGENABLE	FALSE
D3DRS_SEPARATEALPHABLENDENABLE	FALSE
D3DRS_SHADEMODE	D3DSHADE_GOURAUD
D3DRS_SPECULARENABLE	FALSE
D3DRS_SRCBLEND	D3DBLEND_SRCALPHA
D3DRS_SRGBWRITEENABLE	FALSE
D3DRS_STENCILENABLE	FALSE
D3DRS_VERTEXBLEND	FALSE
D3DRS_WRAP0	0

Texture Stage States:

Stage Identifier	Type (D3DTEXTURESTAGESTATETYPE)	Value
0	D3DTSS_ALPHAARG1	D3DTA_TEXTURE
0	D3DTSS_ALPHAARG2	D3DTA_DIFFUSE
0	D3DTSS_ALPHAOP	D3DTOP_MODULATE
0	D3DTSS_COLORARG1	D3DTA_TEXTURE
0	D3DTSS_COLORARG2	D3DTA_DIFFUSE
0	D3DTSS_COLOROP	D3DTOP_MODULATE
0	D3DTSS_TEXCOORDINDEX	0
0	D3DTSS_TEXTURETRANSFORMFLAGS	D3DTTFF_DISABLE
1	D3DTSS_ALPHAOP	D3DTOP_DISABLE
1	D3DTSS_COLOROP	D3DTOP_DISABLE

Sampler States:

Sampler Stage Index	Type (D3DSAMPLERSTATETYPE)	Value
0	D3DSAMP_ADDRESSU	D3DTADDRESS_CLAMP
0	D3DSAMP_ADDRESSV	D3DTADDRESS_CLAMP
0	D3DSAMP_MAGFILTER	D3DTEXF_ANISOTROPIC if TextureFilterCaps includes D3DPTFILTERCAPS_MAGFANISOTROPIC; otherwise D3DTEXF_LINEAR
0	D3DSAMP_MAXMIPLEVEL	0
0	D3DSAMP_MAXANISOTROPY	MaxAnisotropy
0	D3DSAMP_MINFILTER	D3DTEXF_ANISOTROPIC if TextureFilterCaps includes D3DPTFILTERCAPS_MINFANISOTROPIC; otherwise D3DTEXF_LINEAR
0	D3DSAMP_MIPFILTER	D3DTEXF_LINEAR if TextureFilterCaps includes D3DPTFILTERCAPS_MIPFLINEAR; otherwise D3DTEXF_POINT
0	D3DSAMP_MIPMAPLODBIAS	0
0	D3DSAMP_SRGBTEXTURE	0

Note    This method disables N-patches.

D3DXSPRITE

The following flags are used to specify sprite rendering options to the flags parameter in the ID3DXSprite::Begin method:

#define	Description
D3DXSPRITE_DONOTSAVESTATE	The device state is not to be saved or restored when ID3DXSprite::Begin or ID3DXSprite::End is called.
D3DXSPRITE_DONOTMODIFY_RENDERSTATE	The device render state is not to be changed when ID3DXSprite::Begin is called. The device is assumed to be in a valid state to draw vertices containing UsageIndex = 0 in the D3DDECLUSAGE_POSITION, D3DDECLUSAGE_TEXCOORD, and D3DDECLUSAGE_COLOR data.
D3DXSPRITE_OBJECTSPACE	The world, view, and projection transforms are not modified. The transforms currently set to the device are used to transform the sprites when the batched sprites are drawn (when ID3DXSprite::Flush or ID3DXSprite::End is called). If this flag is not specified, then world, view, and projection transforms are modified so that sprites are drawn in screen-space coordinates.
D3DXSPRITE_BILLBOARD	Each sprite will be rotated about its center so that it is facing the viewer. ID3DXSprite::SetWorldViewLH or ID3DXSprite::SetWorldViewRH must be called first.
D3DXSPRITE_ALPHABLEND	Enables alpha blending with D3DRS_ALPHATESTENABLE set to TRUE (for nonzero alpha). D3DBLEND_SRCALPHA will be the source blend state, and D3DBLEND_INVSRCALPHA will be the destination blend state in calls to IDirect3DDevice9::SetRenderState. See Alpha Blending State (Direct3D 9). ID3DXFont expects this flag to be set when drawing text.
D3DXSPRITE_SORT_TEXTURE	Sort sprites by texture prior to drawing. This can improve performance when drawing non-overlapping sprites of uniform depth. You may also combine D3DXSPRITE_SORT_TEXTURE with either D3DXSPRITE_SORT_DEPTH_FRONTTOBACK or D3DXSPRITE_SORT_DEPTH_BACKTOFRONT. This will sort the list of sprites by depth first and texture second.
D3DXSPRITE_SORT_DEPTH_FRONTTOBACK	Sprites are sorted by depth in front-to-back order prior to drawing. This procedure is recommended when drawing opaque sprites of varying depths. You may combine D3DXSPRITE_SORT_DEPTH_FRONTTOBACK with D3DXSPRITE_SORT_TEXTURE to sort first by depth, and second by texture.
D3DXSPRITE_SORT_DEPTH_BACKTOFRONT	Sprites are sorted by depth in back-to-front order prior to drawing. This procedure is recommended when drawing transparent sprites of varying depths. You may combine D3DXSPRITE_SORT_DEPTH_BACKTOFRONT with D3DXSPRITE_SORT_TEXTURE to sort first by depth, and second by texture.
D3DXSPRITE_DO_NOT_ADDREF_TEXTURE	Disables calling AddRef() on every draw, and Release() on Flush() for better performance.

 

初始化ID3DXSprite和ID3DXFont對象

在回調(diào)函數(shù)OnCreateDevice()中創(chuàng)建ID3DXFont對象：

//--------------------------------------------------------------------------------------
// Create any D3DPOOL_MANAGED resources here 
//--------------------------------------------------------------------------------------
HRESULT CALLBACK OnCreateDevice( IDirect3DDevice9* pd3dDevice, const D3DSURFACE_DESC* pBackBufferSurfaceDesc, 
								 void* pUserContext )
{
	D3DXCreateFont(pd3dDevice, 18, 0, FW_BOLD, 1, FALSE, DEFAULT_CHARSET, OUT_DEFAULT_PRECIS, DEFAULT_QUALITY,
				   DEFAULT_PITCH | FF_DONTCARE, L"Arial", &g_font);

    return S_OK;
}

 

繪制文本

//--------------------------------------------------------------------------------------
// Render the helper information
//--------------------------------------------------------------------------------------
void RenderText()
{
	CDXUTTextHelper text_helper(g_font, g_text_sprite, 20);
	

	text_helper.Begin();

	// show frame and device states
	text_helper.SetInsertionPos(5, 5);
	text_helper.SetForegroundColor( D3DXCOLOR(1.0f, 0.475f, 0.0f, 1.0f) );
	text_helper.DrawTextLine( DXUTGetFrameStats(true) );
	text_helper.DrawTextLine( DXUTGetDeviceStats() );

	// show other simple information
	text_helper.SetForegroundColor( D3DXCOLOR(1.0f, 1.0f, 1.0f, 1.0f) );
	text_helper.DrawTextLine(L"Put whatever misc status here");

	// show helper information
	

	const D3DSURFACE_DESC* surface_desc = DXUTGetBackBufferSurfaceDesc();

	if(g_show_help)
	{
		text_helper.SetInsertionPos(10, surface_desc->Height - 15 * 6);
		text_helper.SetForegroundColor( D3DXCOLOR(1.0f, 0.475f, 0.0f, 1.0f) );
		text_helper.DrawTextLine(L"Controls (F1 to hide):");
		

		text_helper.SetInsertionPos(40, surface_desc->Height - 15 * 5);
		text_helper.DrawTextLine(L"Quir: ESC");
	}
	else
	{
		text_helper.SetInsertionPos(10, surface_desc->Height - 15 * 4);
		text_helper.SetForegroundColor( D3DXCOLOR(1.0f, 1.0f, 1.0f, 1.0f) );
		text_helper.DrawTextLine(L"Press F1 for help");
	}

	text_helper.End();
}

 

處理鍵盤消息

程序通過鍵盤上的"F1"鍵切換來表明是否顯示簡單幫助文本，處理代碼如下：

//--------------------------------------------------------------------------------------
// Handle keybaord event
//--------------------------------------------------------------------------------------
void CALLBACK OnKeyboardProc(UINT charater, bool is_key_down, bool is_alt_down, void* user_context)
{
	if(is_key_down)
	{
		switch(charater)
		{
		case VK_F1:
			g_show_help = !g_show_help;
			break;
		}
	}
}

 

運行效果圖：

 

主程序：

 

 

下載示例工程