问题
I have a scene with objects intersected using Lambert material, like in this jsFiddle.
Now I need/want to switch the material of that plane to a Shader material and the plane turns into a background thing, like here.
The question is, can I use different materials in objects and still preserve the intersection effect? Is this a Three.js limitation or this is how shaders works? Or am I missing a parameter in the renderer/material?
At the moment is not an option no switch all my work to shader materials in order to take advantage of shaders.
This is how I set up the material:
var material1 = new THREE.ShaderMaterial( {
uniforms: {
color: { type: "c", value: new THREE.Color( 0x22A8E7 ) }
},
vertexShader: document.getElementById( 'vertexShader' ).textContent,
fragmentShader: document.getElementById( 'fragmentShader' ).textContent,
opacity: 0.5,
transparent: true,
} );
Thanks!
回答1:
With ShaderMaterial you control the shader glsl; so in order for logarithmicDepthBuffer to work you need to add four sets of code to your shaders.
The code is in:
Vertex shader declares
https://github.com/mrdoob/three.js/blob/master/src/renderers/shaders/ShaderChunk/logdepthbuf_pars_vertex.glsl
#ifdef USE_LOGDEPTHBUF
#ifdef USE_LOGDEPTHBUF_EXT
varying float vFragDepth;
#endif
uniform float logDepthBufFC;
#endif
Vertex shader body
https://github.com/mrdoob/three.js/blob/master/src/renderers/shaders/ShaderChunk/logdepthbuf_vertex.glsl
#ifdef USE_LOGDEPTHBUF
gl_Position.z = log2(max( EPSILON, gl_Position.w + 1.0 )) * logDepthBufFC;
#ifdef USE_LOGDEPTHBUF_EXT
vFragDepth = 1.0 + gl_Position.w;
#else
gl_Position.z = (gl_Position.z - 1.0) * gl_Position.w;
#endif
#endif
Fragment shader declares
https://github.com/mrdoob/three.js/blob/master/src/renderers/shaders/ShaderChunk/logdepthbuf_pars_fragment.glsl
#ifdef USE_LOGDEPTHBUF
uniform float logDepthBufFC;
#ifdef USE_LOGDEPTHBUF_EXT
#extension GL_EXT_frag_depth : enable
varying float vFragDepth;
#endif
#endif
Fragment shader body
https://github.com/mrdoob/three.js/blob/master/src/renderers/shaders/ShaderChunk/logdepthbuf_fragment.glsl
#if defined(USE_LOGDEPTHBUF) && defined(USE_LOGDEPTHBUF_EXT)
gl_FragDepthEXT = log2(vFragDepth) * logDepthBufFC * 0.5;
#endif
If you are building the shaders in js, rather than pulling directly from the HTML then you can include these with ShaderChunks e.g. THREE.ShaderChunk[ "logdepthbuf_pars_vertex" ]
See https://github.com/mrdoob/three.js/blob/master/src/renderers/shaders/ShaderLib.js for examples of this.
回答2:
Ok, looking for another subject, I've found this example http://stemkoski.github.io/Three.js/Shader-Glow.html.
The "problem" in my tests was the logarithmic depth buffer in this line:
var renderer = new THREE.WebGLRenderer({logarithmicDepthBuffer: true});
Without that option, worked as expected.
Now, I don't know if that is a bug in THREE or in order to use logarithmic depth buffer I must write the shader in another way, or it just the way it is.
来源:https://stackoverflow.com/questions/29217468/three-js-objects-intersected-and-shader-material