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2007年11月17日
2007年11月16日
2007年11月15日
刚刚接触CEGUI,在原D3D程序上画了一个小窗口后,发现渲染效果于以前的大相径庭,查看了源代码后发现,原来CEGUI在渲染后并没有恢复到默认的渲染状态,于是改之,再编译、运行、一切正常。。。
下面是恢复其渲染状态的代码,与初始化渲染状态函数initPerFrameStates()对应
1
void
DirectX9Renderer::UnitFrameStates()
2
{
3
//
setup vertex stream
4
5
d_device
->
SetFVF(NULL);
6
7
//
set device states
8
d_device
->
SetRenderState(D3DRS_ZENABLE, D3DZB_TRUE);
9
d_device
->
SetRenderState(D3DRS_FILLMODE, D3DFILL_SOLID);
10
d_device
->
SetRenderState(D3DRS_ALPHATESTENABLE, FALSE);
11
d_device
->
SetRenderState(D3DRS_ZWRITEENABLE, TRUE);
12
d_device
->
SetRenderState(D3DRS_FOGENABLE, FALSE);
13
d_device
->
SetRenderState(D3DRS_CULLMODE, D3DCULL_CCW);
14
15
16
//
setup texture addressing settings/*
17
d_device
->
SetSamplerState(
0
, D3DSAMP_ADDRESSU, D3DTADDRESS_WRAP);
18
d_device
->
SetSamplerState(
0
, D3DSAMP_ADDRESSV, D3DTADDRESS_WRAP);
19
20
//
setup colour calculations
21
d_device
->
SetTextureStageState(
0
, D3DTSS_COLORARG1, D3DTA_TEXTURE);
22
d_device
->
SetTextureStageState(
0
, D3DTSS_COLORARG2, D3DTA_CURRENT);
23
d_device
->
SetTextureStageState(
0
, D3DTSS_COLOROP, D3DTOP_SELECTARG1);
24
25
//
setup alpha calculations
26
d_device
->
SetTextureStageState(
0
, D3DTSS_ALPHAARG1, D3DTA_TEXTURE);
27
d_device
->
SetTextureStageState(
0
, D3DTSS_ALPHAARG2, D3DTA_CURRENT);
28
d_device
->
SetTextureStageState(
0
, D3DTSS_ALPHAOP, D3DTOP_SELECTARG1);
29
30
//
setup filtering
31
d_device
->
SetSamplerState(
0
, D3DSAMP_MINFILTER, D3DTEXF_POINT);
32
d_device
->
SetSamplerState(
0
, D3DSAMP_MAGFILTER, D3DTEXF_POINT);
33
34
//
disable texture stages we do not need.
35
d_device
->
SetTextureStageState(
1
, D3DTSS_COLOROP, D3DTOP_DISABLE);
36
37
//
setup scene alpha blending
38
d_device
->
SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE);
39
d_device
->
SetRenderState(D3DRS_SRCBLEND, D3DBLEND_ONE);
40
d_device
->
SetRenderState(D3DRS_DESTBLEND, D3DBLEND_ZERO);
42
}
另外CEGUI有2种渲染模式:立即渲染和缓冲渲染。所以在这2种渲染模式结束后都需要调用上面的代码以恢复渲染状态
Direct3D计算Alpha混合的颜色公式:
Color = ( SrcRGB * SrcK ) + ( DestRGB * DestK )
SrcRGB表示源颜色值,即将要绘制的颜色值。SrcK表示源混合系数,通常赋值为D3DBLEND_SRCALPHA,即当前绘制像素的Alpha值
DestRGB表示目标颜色值,即当前缓冲区中的颜色值。DestK表示目标系数,通常赋值为D3DBLEND_INVSRCALPHA,即1减去当前绘制像素的Alpha值
则Direct3D计算Alpha混合的颜色公式可表示为
Color = ( SrcRGB * SrcAlpha ) + ( DestRGB * ( 1 - SrcAlpha ) )
混合步骤
Alpha混合默认关闭,所以首先需要开启它
Device -> SetRenderState( D3DRS_ALPHABLENDENABLE, true );
然后设置Alpha混合系数
Device -> SetRenderState( D3DRS_SRCBLEND, D3DBLEND_SRCALPHA );
Device -> SetRenderState( D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);
还要指定资源(材质或Alpha通道)
Alpha通道可用DirectX自带的纹理工具创建,为DDS文件
DEMO演示图片:
地形一般是用网格再从高度图里读取每个顶点的高度来生成。若进一步,想实现摄像机在地形上行走的效果,就需要算出地形上任意一点的高度。总结了3个方法: 一: 《Introduction to 3D Game Programming With Directx 9.0》这本书里介绍的,利用向量来算。
1
float
Terrain::GetHeight(
float
x,
float
z)
2
{
3
//
Translate on xz-plane by the transformation that takes
4
//
the terrain START point to the origin.
5
x
=
((
float
)_width
/
2.0f
)
+
x;
6
z
=
((
float
)_depth
/
2.0f
)
-
z;
7
//
Scale down by the transformation that makes the
8
//
cellspacing equal to one. This is given by
9
//
1 / cellspacing since; cellspacing * 1 / cellspacing = 1.
10
x
/=
(
float
)_CellSpacing;
11
z
/=
(
float
)_CellSpacing;
12
//
From now on, we will interpret our positive z-axis as
13
//
going in the 'down' direction, rather than the 'up' direction.
14
//
This allows to extract the row and column simply by 'flooring'
15
//
x and z:
16
float
col
=
::floorf(x);
17
float
row
=
::floorf(z);
18
//
get the heights of the quad we're in:
19
//
20
//
A B
21
//
*---*
22
//
| / |
23
//
*---*
24
//
C D
25
float
A
=
GetHeightMapEntry(row, col);
26
float
B
=
GetHeightMapEntry(row, col
+
1
);
27
float
C
=
GetHeightMapEntry(row
+
1
, col);
28
float
D
=
GetHeightMapEntry(row
+
1
, col
+
1
);
29
//
30
//
Find the triangle we are in:
31
//
32
//
Translate by the transformation that takes the upper-left
33
//
corner of the cell we are in to the origin. Recall that our
34
//
cellspacing was nomalized to 1. Thus we have a unit square
35
//
at the origin of our +x -> 'right' and +z -> 'down' system.
36
float
dx
=
x
-
col;
37
float
dz
=
z
-
row;
38
//
Note the below compuations of u and v are unneccessary, we really
39
//
only need the height, but we compute the entire vector to emphasis
40
//
the books discussion.
41
float
height
=
0.0f
;
42
if
(dz
<
1.0f
-
dx)
//
upper triangle ABC
43
{
44
float
uy
=
B
-
A;
//
A->B
45
float
vy
=
C
-
A;
//
A->C
46
//
Linearly interpolate on each vector. The height is the vertex
47
//
height the vectors u and v originate from {A}, plus the heights
48
//
found by interpolating on each vector u and v.
49
height
=
A
+
Lerp(
0.0f
, uy, dx)
+
Lerp(
0.0f
, vy, dz);
50
}
51
else
//
lower triangle DCB
52
{
53
float
uy
=
C
-
D;
//
D->C
54
float
vy
=
B
-
D;
//
D->B
55
//
Linearly interpolate on each vector. The height is the vertex
56
//
height the vectors u and v originate from {D}, plus the heights
57
//
found by interpolating on each vector u and v.
58
height
=
D
+
Lerp(
0.0f
, uy,
1.0f
-
dx)
+
Lerp(
0.0f
, vy,
1.0f
-
dz);
59
}
60
return
height;
61
}
62
用到的2个函数
1float Terrain::Lerp(float a, float b, float t) //一个插值函数 2{ 3 return (a - (a*t) + (b*t)); 4} 5 6int Terrain::GetHeightMapEntry(int row, int col) //读取高度函数 7{ 8 return _heightmap[row * _numVertsPerRow + col]; // 高度图数据存在_heightmap里 9} 二: 先计算出摄像机所在三角形的平面方程,然后带入摄像机的X,Z坐标,即可得高度Y 具体实现过程见http://creatorchen1984.spaces.live.com/ 《获取地形上某一点高度》,写的十分详细 三: 网上找的一个方法 假设你的地形为terrain[][];用下面的函数求出地形上点(x,z);的y值,将人物的高度加上这个y值即可.
1float GetHeight(GLfloat x, GLfloat z) 2{ 3float h=0; 4float Xb,Yb; 5int Xa,Ya; 6Xa=(int)x; 7Ya=(int)z; 8Xb=x-Xa; 9Yb=z-Ya; 10float a=terrain[Xa][Ya].y; 11float b=terrain[Xa+1][Ya].y; 12float c=terrain[Xa][Ya+1].y; 13float d=terrain[Xa+1][Ya+1].y; 14h=(a*(1-Xb)+b*Xb)*(1-Yb)+(c*(1-Xb)+d*Xb)*Yb; 15return h; 16} 17
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