半透明物体边缘透射的简单模拟

王朝other·作者佚名  2006-01-10
窄屏简体版  字體: |||超大  

半透明物体边缘透射/散射这样的效果应该用SSS(Sub-Surface Scatter)的技术来模拟,通俗点说就是玉的效果.但是本人数学不过关,看不懂SSS :-( ,.

今天早上在想,如果考虑到物体的在沿着视线方向的厚度,以及正对光源的程度,是不是也可以出来点半透明的效果呢?

来不及写一个程序来计算物体表面的厚度信息, 所以假设,越是边缘的地方,越薄.

shader很简单. 用RenderMonkey写的。

http://xreal.51.net/Game/fakess.rfx

//Vertex Shader use GLSL

uniform vec3 fvLightPosition;

uniform vec3 fvEyePosition;

varying vec2 Texcoord;

varying vec3 ViewDirection;

varying vec3 LightDirection;

varying vec3 Normal;

void main( void )

{

gl_Position = ftransform();

Texcoord = gl_MultiTexCoord0.xy;

vec4 fvObjectPosition = gl_ModelViewMatrix * gl_Vertex;

ViewDirection = fvEyePosition - fvObjectPosition.xyz;

LightDirection = fvLightPosition - fvObjectPosition.xyz;

Normal = gl_NormalMatrix * gl_Normal;

}

//Pixel Shader use GLSL

uniform vec4 fvAmbient;

uniform vec4 fvSpecular;

uniform vec4 fvDiffuse;

uniform vec4 fvScatter;

uniform float fSpecularPower;

uniform float fLightPower;

uniform float fScatterPower;

uniform sampler2D baseMap;

varying vec2 Texcoord;

varying vec3 ViewDirection;

varying vec3 LightDirection;

varying vec3 Normal;

void main( void )

{

vec3 fvLightDirection = normalize( LightDirection );

vec3 fvNormal = normalize( Normal );

float fNDotL = dot( fvNormal, fvLightDirection );

vec3 fvReflection = normalize( ( ( 2.0 * fvNormal ) * fNDotL ) - fvLightDirection );

vec3 fvViewDirection = normalize( ViewDirection );

float fRDotV = max( 0.0, dot( fvReflection, fvViewDirection ) );

vec4 fvBaseColor = texture2D( baseMap, Texcoord );

vec4 fvTotalAmbient = fvAmbient ;

vec4 fvTotalDiffuse = fvDiffuse * fNDotL * fvBaseColor;

vec4 fvTotalSpecular = fvSpecular * ( pow( fRDotV, fSpecularPower ) );

float thickness = 1.0 - dot(fvViewDirection, fvNormal);

float viewness = fLightPower - fNDotL;

vec4 vTrCl = fScatterPower * viewness * thickness * fvScatter;

gl_FragColor = vTrCl + ( fvTotalAmbient + fvTotalDiffuse + fvTotalSpecular );

}

 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
 
 
© 2005- 王朝網路 版權所有 導航