Unity UNITY_MATRIX_MVP resterizing calculation

렌더링 파이프라인의 좌표 공간들 – Rapapa Dev Story
Name	Value
UNITY_MATRIX_MVP	Current model * view * projection matrix.
UNITY_MATRIX_MV	Current model * view matrix.
UNITY_MATRIX_V	Current view matrix.
UNITY_MATRIX_P	Current projection matrix.
UNITY_MATRIX_VP	Current view * projection matrix.
UNITY_MATRIX_T_MV	Transpose of model * view matrix.
UNITY_MATRIX_IT_MV	Inverse transpose of model * view matrix.
unity_ObjectToWorld	Current model matrix.
unity_WorldToObject	Inverse of current world matrix.

UNITY_MATRIX_MVP는 Local Space의 Vertex를 Clip space로 옮겨주는 Matrix이다. 

Here is my shader:

Code (csharp):

1.  
2. Shader "Custom/Test" {
3.     Properties {
4.         _MainTex("Texture", 2D) = "white" { }  
5.     }
6.    
7.     SubShader{ 
8.    
9.     Pass{
10.    
11.     Cull Back
12.    
13.     CGPROGRAM
14.     #pragma vertex vert
15.     #pragma fragment frag
16.    
17.     #include "UnityCG.cginc"
18.    
19.     sampler2D _MainTex;
20.     float4x4 _MATRIX_MVP;
21.  
22.     struct v2f{
23.         float4  pos : SV_POSITION;
24.         float2  uv : TEXCOORD0;
25.     };
26.  
27.     v2f vert(appdata_base v){
28.        
29.         v2f o;
30.         float2 screenSpacePos;
31.         float4 clipPos;
32.    
33.         //Convert position from world space to clip space.
34.         //Only the UV coordinates should be frozen, so use a different matrix
35.         clipPos = mul(_MATRIX_MVP, v.vertex);
36.        
37.         //Convert position from clip space to screen space.
38.         //Screen space has range x=-1 to x=1
39.         screenSpacePos.x = clipPos.x / clipPos.w;
40.         screenSpacePos.y = clipPos.y / clipPos.w;
41.  
42.         //the screen space range (-1 to 1) has to be converted to
43.         //the UV range 0 to 1
44.         o.uv.x = (0.5f*screenSpacePos.x) + 0.5f;
45.         o.uv.y = (0.5f*screenSpacePos.y) + 0.5f;
46.    
47.         //The position of the vertex should not be frozen, so use
48.         //the standard UNITY_MATRIX_MVP matrix
49.         o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
50.  
51.         return o;
52.     }
53.    
54.     half4 frag(v2f i) : COLOR{
55.    
56.         half4 texcol = tex2D(_MainTex, i.uv);
57.         return texcol;
58.     }
59.    
60.     ENDCG
61.    
62.     }
63.     }
64. }
65.  

From Unity I call:

Code (csharp):

1.  
2. Matrix4x4 P = GL.GetGPUProjectionMatrix(Camera.main.projectionMatrix, false);
3. Matrix4x4 V = Camera.main.worldToCameraMatrix;
4. Matrix4x4 M = debugObject.renderer.localToWorldMatrix;
5. Matrix4x4 MVP = P * V * M;
6. debugObject.renderer.material.SetMatrix("_MATRIX_MVP", MVP);
7.