引子——UGUI中的Text如何被绘制到屏幕上?

参与绘制Text的角色:

  • VertexHelper
  • TextGenerator
  • Font和FontData
  • BaseMeshEffect

这是字体使用的Shader

Shader
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

Shader "GUI/Text Shader" {
Properties {
_MainTex ("Font Texture", 2D) = "white" {}
_Color ("Text Color", Color) = (1,1,1,1)
}

SubShader {

Tags {
"Queue"="Transparent"
"IgnoreProjector"="True"
"RenderType"="Transparent"
"PreviewType"="Plane"
}
Lighting Off Cull Off ZTest Always ZWrite Off
Blend SrcAlpha OneMinusSrcAlpha

Pass {
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma multi_compile _ UNITY_SINGLE_PASS_STEREO STEREO_INSTANCING_ON STEREO_MULTIVIEW_ON
#include "UnityCG.cginc"

struct appdata_t {
float4 vertex : POSITION;
fixed4 color : COLOR;
float2 texcoord : TEXCOORD0;
UNITY_VERTEX_INPUT_INSTANCE_ID
};

struct v2f {
float4 vertex : SV_POSITION;
fixed4 color : COLOR;
float2 texcoord : TEXCOORD0;
UNITY_VERTEX_OUTPUT_STEREO
};

sampler2D _MainTex;
uniform float4 _MainTex_ST;
uniform fixed4 _Color;

v2f vert (appdata_t v)
{
v2f o;
UNITY_SETUP_INSTANCE_ID(v);
UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
o.vertex = UnityObjectToClipPos(v.vertex);
o.color = v.color * _Color;
o.texcoord = TRANSFORM_TEX(v.texcoord,_MainTex);
return o;
}

fixed4 frag (v2f i) : SV_Target
{
fixed4 col = i.color;
col.a *= tex2D(_MainTex, i.texcoord).a;
return col;
}
ENDCG
}
}
}

这是所有的UGUI默认使用的Shader

Shader
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
// Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)

Shader "UI/Default"
{
Properties
{
[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
_Color ("Tint", Color) = (1,1,1,1)

_StencilComp ("Stencil Comparison", Float) = 8
_Stencil ("Stencil ID", Float) = 0
_StencilOp ("Stencil Operation", Float) = 0
_StencilWriteMask ("Stencil Write Mask", Float) = 255
_StencilReadMask ("Stencil Read Mask", Float) = 255

_ColorMask ("Color Mask", Float) = 15

[Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0
}

SubShader
{
Tags
{
"Queue"="Transparent"
"IgnoreProjector"="True"
"RenderType"="Transparent"
"PreviewType"="Plane"
"CanUseSpriteAtlas"="True"
}

Stencil
{
Ref [_Stencil]
Comp [_StencilComp]
Pass [_StencilOp]
ReadMask [_StencilReadMask]
WriteMask [_StencilWriteMask]
}

Cull Off
Lighting Off
ZWrite Off
ZTest [unity_GUIZTestMode]
Blend One OneMinusSrcAlpha
ColorMask [_ColorMask]

Pass
{
Name "Default"
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#pragma target 2.0

#include "UnityCG.cginc"
#include "UnityUI.cginc"

#pragma multi_compile_local _ UNITY_UI_CLIP_RECT
#pragma multi_compile_local _ UNITY_UI_ALPHACLIP

struct appdata_t
{
float4 vertex : POSITION;
float4 color : COLOR;
float2 texcoord : TEXCOORD0;
UNITY_VERTEX_INPUT_INSTANCE_ID
};

struct v2f
{
float4 vertex : SV_POSITION;
fixed4 color : COLOR;
float2 texcoord : TEXCOORD0;
float4 worldPosition : TEXCOORD1;
float4 mask : TEXCOORD2;
UNITY_VERTEX_OUTPUT_STEREO
};

sampler2D _MainTex;
fixed4 _Color;
fixed4 _TextureSampleAdd;
float4 _ClipRect;
float4 _MainTex_ST;
float _UIMaskSoftnessX;
float _UIMaskSoftnessY;

v2f vert(appdata_t v)
{
v2f OUT;
UNITY_SETUP_INSTANCE_ID(v);
UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
float4 vPosition = UnityObjectToClipPos(v.vertex);
OUT.worldPosition = v.vertex;
OUT.vertex = vPosition;

float2 pixelSize = vPosition.w;
pixelSize /= float2(1, 1) * abs(mul((float2x2)UNITY_MATRIX_P, _ScreenParams.xy));

float4 clampedRect = clamp(_ClipRect, -2e10, 2e10);
float2 maskUV = (v.vertex.xy - clampedRect.xy) / (clampedRect.zw - clampedRect.xy);
OUT.texcoord = TRANSFORM_TEX(v.texcoord.xy, _MainTex);
OUT.mask = float4(v.vertex.xy * 2 - clampedRect.xy - clampedRect.zw, 0.25 / (0.25 * half2(_UIMaskSoftnessX, _UIMaskSoftnessY) + abs(pixelSize.xy)));

OUT.color = v.color * _Color;
return OUT;
}

fixed4 frag(v2f IN) : SV_Target
{
half4 color = IN.color * (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd);

#ifdef UNITY_UI_CLIP_RECT
half2 m = saturate((_ClipRect.zw - _ClipRect.xy - abs(IN.mask.xy)) * IN.mask.zw);
color.a *= m.x * m.y;
#endif

#ifdef UNITY_UI_ALPHACLIP
clip (color.a - 0.001);
#endif

color.rgb *= color.a;

return color;
}
ENDCG
}
}
}

参考资料