Cg 程式設計/Unity/雙面表面
本教程涵蓋了雙面每頂點照明。
它是關於 Unity 中基礎照明的系列教程的一部分。在本教程中，我們擴充套件了“鏡面高光”部分以渲染雙面表面。如果您還沒有閱讀“鏡面高光”部分，現在是閱讀的好時機。
正如代數曲面圖所示，有時需要對曲面的兩側應用不同的顏色。在“截面”部分中，我們看到了如何使用正面剔除和背面剔除的兩個通道來對網格的兩側應用不同的著色器。我們將在本教程中應用相同的策略。
正如在“截面”部分中提到的，Cg 中的另一種方法是使用一個語義為 VFACE 的片段輸入引數來區分兩個側面，請參閱Unity 的著色器語義文件.
雙面每頂點照明的著色器程式碼是對“鏡面高光”部分中程式碼的直接擴充套件。它需要兩組材質引數（正面和背面），並複製所有通道 - 一份帶有正面剔除，另一份帶有背面剔除。這兩個副本的著色器是相同的，除了背面著色器使用反轉的表面法線向量和背面材質的屬性。
Shader "Cg two-sided per-vertex lighting" {
Properties {
_Color ("Front Material Diffuse Color", Color) = (1,1,1,1)
_SpecColor ("Front Material Specular Color", Color) = (1,1,1,1)
_Shininess ("Front Material Shininess", Float) = 10
_BackColor ("Back Material Diffuse Color", Color) = (1,1,1,1)
_BackSpecColor ("Back Material Specular Color", Color)
= (1,1,1,1)
_BackShininess ("Back Material Shininess", Float) = 10
}
SubShader {
Pass {
Tags { "LightMode" = "ForwardBase" }
// pass for ambient light and first light source
Cull Back // render only front faces
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
uniform float4 _LightColor0;
// color of light source (from "Lighting.cginc")
// User-specified properties
uniform float4 _Color;
uniform float4 _SpecColor;
uniform float _Shininess;
uniform float4 _BackColor;
uniform float4 _BackSpecColor;
uniform float _BackShininess;
struct vertexInput {
float4 vertex : POSITION;
float3 normal : NORMAL;
};
struct vertexOutput {
float4 pos : SV_POSITION;
float4 col : COLOR;
};
vertexOutput vert(vertexInput input)
{
vertexOutput output;
float4x4 modelMatrix = unity_ObjectToWorld;
float4x4 modelMatrixInverse = unity_WorldToObject;
float3 normalDirection = normalize(
mul(float4(input.normal, 0.0), modelMatrixInverse).xyz);
float3 viewDirection = normalize(_WorldSpaceCameraPos
- mul(modelMatrix, input.vertex).xyz);
float3 lightDirection;
float attenuation;
if (0.0 == _WorldSpaceLightPos0.w) // directional light?
{
attenuation = 1.0; // no attenuation
lightDirection = normalize(_WorldSpaceLightPos0.xyz);
}
else // point or spot light
{
float3 vertexToLightSource = _WorldSpaceLightPos0.xyz
- mul(modelMatrix, input.vertex).xyz;
float distance = length(vertexToLightSource);
attenuation = 1.0 / distance; // linear attenuation
lightDirection = normalize(vertexToLightSource);
}
float3 ambientLighting =
UNITY_LIGHTMODEL_AMBIENT.rgb * _Color.rgb;
float3 diffuseReflection =
attenuation * _LightColor0.rgb * _Color.rgb
* max(0.0, dot(normalDirection, lightDirection));
float3 specularReflection;
if (dot(normalDirection, lightDirection) < 0.0)
// light source on the wrong side?
{
specularReflection = float3(0.0, 0.0, 0.0);
// no specular reflection
}
else // light source on the right side
{
specularReflection = attenuation * _LightColor0.rgb
* _SpecColor.rgb * pow(max(0.0, dot(
reflect(-lightDirection, normalDirection),
viewDirection)), _Shininess);
}
output.col = float4(ambientLighting + diffuseReflection
+ specularReflection, 1.0);
output.pos = UnityObjectToClipPos(input.vertex);
return output;
}
float4 frag(vertexOutput input) : COLOR
{
return input.col;
}
ENDCG
}
Pass {
Tags { "LightMode" = "ForwardAdd" }
// pass for additional light sources
Blend One One // additive blending
Cull Back // render only front faces
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
uniform float4 _LightColor0;
// color of light source (from "Lighting.cginc")
// User-specified properties
uniform float4 _Color;
uniform float4 _SpecColor;
uniform float _Shininess;
uniform float4 _BackColor;
uniform float4 _BackSpecColor;
uniform float _BackShininess;
struct vertexInput {
float4 vertex : POSITION;
float3 normal : NORMAL;
};
struct vertexOutput {
float4 pos : SV_POSITION;
float4 col : COLOR;
};
vertexOutput vert(vertexInput input)
{
vertexOutput output;
float4x4 modelMatrix = unity_ObjectToWorld;
float4x4 modelMatrixInverse = unity_WorldToObject;
float3 normalDirection = normalize(
mul(float4(input.normal, 0.0), modelMatrixInverse).xyz);
float3 viewDirection = normalize(_WorldSpaceCameraPos
- mul(modelMatrix, input.vertex).xyz);
float3 lightDirection;
float attenuation;
if (0.0 == _WorldSpaceLightPos0.w) // directional light?
{
attenuation = 1.0; // no attenuation
lightDirection = normalize(_WorldSpaceLightPos0.xyz);
}
else // point or spot light
{
float3 vertexToLightSource = _WorldSpaceLightPos0.xyz
- mul(modelMatrix, input.vertex).xyz;
float distance = length(vertexToLightSource);
attenuation = 1.0 / distance; // linear attenuation
lightDirection = normalize(vertexToLightSource);
}
float3 diffuseReflection =
attenuation * _LightColor0.rgb * _Color.rgb
* max(0.0, dot(normalDirection, lightDirection));
float3 specularReflection;
if (dot(normalDirection, lightDirection) < 0.0)
// light source on the wrong side?
{
specularReflection = float3(0.0, 0.0, 0.0);
// no specular reflection
}
else // light source on the right side
{
specularReflection = attenuation * _LightColor0.rgb
* _SpecColor.rgb * pow(max(0.0, dot(
reflect(-lightDirection, normalDirection),
viewDirection)), _Shininess);
}
output.col = float4(diffuseReflection
+ specularReflection, 1.0);
// no ambient contribution in this pass
output.pos = UnityObjectToClipPos(input.vertex);
return output;
}
float4 frag(vertexOutput input) : COLOR
{
return input.col;
}
ENDCG
}
Pass {
Tags { "LightMode" = "ForwardBase" }
// pass for ambient light and first light source
Cull Front// render only back faces
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
uniform float4 _LightColor0;
// color of light source (from "Lighting.cginc")
// User-specified properties
uniform float4 _Color;
uniform float4 _SpecColor;
uniform float _Shininess;
uniform float4 _BackColor;
uniform float4 _BackSpecColor;
uniform float _BackShininess;
struct vertexInput {
float4 vertex : POSITION;
float3 normal : NORMAL;
};
struct vertexOutput {
float4 pos : SV_POSITION;
float4 col : COLOR;
};
vertexOutput vert(vertexInput input)
{
vertexOutput output;
float4x4 modelMatrix = unity_ObjectToWorld;
float4x4 modelMatrixInverse = unity_WorldToObject;
float3 normalDirection = normalize(
mul(float4(-input.normal, 0.0), modelMatrixInverse).xyz);
float3 viewDirection = normalize(_WorldSpaceCameraPos
- mul(modelMatrix, input.vertex).xyz);
float3 lightDirection;
float attenuation;
if (0.0 == _WorldSpaceLightPos0.w) // directional light?
{
attenuation = 1.0; // no attenuation
lightDirection = normalize(_WorldSpaceLightPos0.xyz);
}
else // point or spot light
{
float3 vertexToLightSource = _WorldSpaceLightPos0.xyz
- mul(modelMatrix, input.vertex).xyz;
float distance = length(vertexToLightSource);
attenuation = 1.0 / distance; // linear attenuation
lightDirection = normalize(vertexToLightSource);
}
float3 ambientLighting =
UNITY_LIGHTMODEL_AMBIENT.rgb * _BackColor.rgb;
float3 diffuseReflection =
attenuation * _LightColor0.rgb * _BackColor.rgb
* max(0.0, dot(normalDirection, lightDirection));
float3 specularReflection;
if (dot(normalDirection, lightDirection) < 0.0)
// light source on the wrong side?
{
specularReflection = float3(0.0, 0.0, 0.0);
// no specular reflection
}
else // light source on the right side
{
specularReflection = attenuation * _LightColor0.rgb
* _BackSpecColor.rgb * pow(max(0.0, dot(
reflect(-lightDirection, normalDirection),
viewDirection)), _BackShininess);
}
output.col = float4(ambientLighting + diffuseReflection
+ specularReflection, 1.0);
output.pos = UnityObjectToClipPos(input.vertex);
return output;
}
float4 frag(vertexOutput input) : COLOR
{
return input.col;
}
ENDCG
}
Pass {
Tags { "LightMode" = "ForwardAdd" }
// pass for additional light sources
Blend One One // additive blending
Cull Front // render only back faces
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
#include "UnityCG.cginc"
uniform float4 _LightColor0;
// color of light source (from "Lighting.cginc")
// User-specified properties
uniform float4 _Color;
uniform float4 _SpecColor;
uniform float _Shininess;
uniform float4 _BackColor;
uniform float4 _BackSpecColor;
uniform float _BackShininess;
struct vertexInput {
float4 vertex : POSITION;
float3 normal : NORMAL;
};
struct vertexOutput {
float4 pos : SV_POSITION;
float4 col : COLOR;
};
vertexOutput vert(vertexInput input)
{
vertexOutput output;
float4x4 modelMatrix = unity_ObjectToWorld;
float4x4 modelMatrixInverse = unity_WorldToObject;
float3 normalDirection = normalize(
mul(float4(-input.normal, 0.0), modelMatrixInverse).xyz);
float3 viewDirection = normalize(_WorldSpaceCameraPos
- mul(modelMatrix, input.vertex).xyz);
float3 lightDirection;
float attenuation;
if (0.0 == _WorldSpaceLightPos0.w) // directional light?
{
attenuation = 1.0; // no attenuation
lightDirection = normalize(_WorldSpaceLightPos0.xyz);
}
else // point or spot light
{
float3 vertexToLightSource = _WorldSpaceLightPos0.xyz
- mul(modelMatrix, input.vertex).xyz;
float distance = length(vertexToLightSource);
attenuation = 1.0 / distance; // linear attenuation
lightDirection = normalize(vertexToLightSource);
}
float3 diffuseReflection =
attenuation * _LightColor0.rgb * _BackColor.rgb
* max(0.0, dot(normalDirection, lightDirection));
float3 specularReflection;
if (dot(normalDirection, lightDirection) < 0.0)
// light source on the wrong side?
{
specularReflection = float3(0.0, 0.0, 0.0);
// no specular reflection
}
else // light source on the right side
{
specularReflection = attenuation * _LightColor0.rgb
* _BackSpecColor.rgb * pow(max(0.0, dot(
reflect(-lightDirection, normalDirection),
viewDirection)), _BackShininess);
}
output.col = float4(diffuseReflection
+ specularReflection, 1.0);
// no ambient contribution in this pass
output.pos = UnityObjectToClipPos(input.vertex);
return output;
}
float4 frag(vertexOutput input) : COLOR
{
return input.col;
}
ENDCG
}
}
Fallback "Specular"
}
此程式碼包含四個通道，其中第一對通道渲染正面，第二對通道使用反轉的法線向量和背面材質屬性渲染背面。每對中的第二個通道與第一個通道相同，除了混合方式為疊加，並且缺少環境色。
恭喜您完成了這個包含一個長著色器的簡短教程。我們已經看到了
- 如何使用正面剔除和背面剔除來對網格的兩側應用不同的著色器。
- 如何更改背面三角形的 Phong 照明計算。
如果您想了解更多
- 關於單面表面的著色器版本，您應該閱讀“鏡面高光”部分.
- 關於 Cg 中的正面三角形和背面三角形，您應該閱讀“截面”部分.
- 關於使用語義為
VFACE的片段輸入引數來區分正面三角形和背面三角形，請參閱Unity 的著色器語義文件.
除非另有說明，否則本頁上的所有示例原始碼都歸屬公共領域。