Parallax Mapping Shader

ゝ一世哀愁。 2022-08-07 05:42 32阅读 0赞

原文 [http://www.azure.com.cn/default.asp?cat=11&page=2][http_www.azure.com.cn_default.asp_cat_11_page_2]

Parallax Mapping 就是通过高度图中的高度，对纹理坐标进行偏移，  
来视觉上欺骗观察者，产生很有凸凹感个幻觉。

[![uploads/200612/23\_134027\_parallax.jpg][uploads_200612_23_134027_parallax.jpg]][uploads_200612_23_134027_parallax.jpg_uploads_200612_23_134027_parallax.jpg]

uniform vec3 fvLightPosition;  
uniform vec3 fvEyePosition;

varying vec2 Texcoord;  
varying vec3 ViewDirection;  
varying vec3 LightDirection;  
    
attribute vec3 rm\_Binormal;  
attribute vec3 rm\_Tangent;  
    
void main( void )  
\{  
   gl\_Position = ftransform();  
   Texcoord    = gl\_MultiTexCoord0.xy;  
     
   vec4 fvObjectPosition = gl\_ModelViewMatrix \* gl\_Vertex;  
    
   vec3 fvViewDirection  = fvEyePosition - fvObjectPosition.xyz;  
   vec3 fvLightDirection = fvLightPosition - fvObjectPosition.xyz;  
      
   vec3 fvNormal         = gl\_NormalMatrix \* gl\_Normal;  
   vec3 fvBinormal       = gl\_NormalMatrix \* rm\_Binormal;  
   vec3 fvTangent        = gl\_NormalMatrix \* rm\_Tangent;  
       
   ViewDirection.x  = dot( fvTangent, fvViewDirection );  
   ViewDirection.y  = dot( fvBinormal, fvViewDirection );  
   ViewDirection.z  = dot( fvNormal, fvViewDirection );  
    
   LightDirection.x  = dot( fvTangent, fvLightDirection.xyz );  
   LightDirection.y  = dot( fvBinormal, fvLightDirection.xyz );  
   LightDirection.z  = dot( fvNormal, fvLightDirection.xyz );  
    
\}

uniform vec4 fvAmbient;  
uniform vec4 fvSpecular;  
uniform vec4 fvDiffuse;  
uniform float fSpecularPower;

uniform sampler2D baseMap;  
uniform sampler2D bumpMap;  
uniform sampler2D Parallax;

varying vec2 Texcoord;  
varying vec3 ViewDirection;  
varying vec3 LightDirection;

void main( void )  
\{  
   vec3  fvViewDirection  = normalize( ViewDirection );  
   vec4  height           = texture2D( Parallax, Texcoord);  
   float uoffset          = (height.x-0.5)\*0.11\*fvViewDirection.x;  
   float voffset          = (height.x-0.5)\*0.11\*fvViewDirection.y;  
   vec2 modifyTexcoord    = vec2(Texcoord.x+uoffset, Texcoord.y+voffset);   
    
   vec3  fvLightDirection = normalize( LightDirection );  
   vec4  avent = texture2D( bumpMap, modifyTexcoord );  
   float d = dot(avent.xyz, fvLightDirection);  
   float shadow = clamp((d - avent.w) \* 1.8 + 0.5, 0.0, 1.0);  
   shadow = shadow \* shadow \* (3.0 - 2.0 \* shadow);

vec3  fvNormal         = normalize(  avent.xyz \* 2.0 - 1.0  );  
   float fNDotL           = dot( fvNormal, fvLightDirection );  
    
   vec3  fvReflection     = normalize( ( ( 2.0 \* fvNormal ) \* fNDotL ) - fvLightDirection );  
   
   float fRDotV           = max( 0.0, dot( fvReflection, fvViewDirection ) );

vec4  fvBaseColor      = texture2D( baseMap, modifyTexcoord );  
    
   vec4  fvTotalAmbient   = fvAmbient \* fvBaseColor;  
   vec4  fvTotalDiffuse   = fvDiffuse \* fNDotL \* fvBaseColor;  
   vec4  fvTotalSpecular  = fvSpecular \* ( pow( fRDotV, fSpecularPower ) );  
   
   gl\_FragColor = fvTotalAmbient + (fvTotalDiffuse + fvTotalSpecular) \* shadow;  
        
\}

[http_www.azure.com.cn_default.asp_cat_11_page_2]: http://www.azure.com.cn/default.asp?cat=11&page=2
[uploads_200612_23_134027_parallax.jpg]: http://www.azure.com.cn/uploads/200612/23_134027_parallax.jpg
[uploads_200612_23_134027_parallax.jpg_uploads_200612_23_134027_parallax.jpg]: http://writeblog.csdn.net/uploads/200612/23_134027_parallax.jpg