webgl实现三维3d洞穴效果代码-html代码-BFW代码库

代码语言：html

所属分类：三维

代码描述：webgl实现三维3d洞穴效果代码

下面为部分代码预览，完整代码请点击下载或在bfwstudio webide中打开

<!DOCTYPE html>
<html lang="en" >
<head>
  <meta charset="UTF-8">


</head>
<body>
<!-- partial:index.partial.html -->
<canvas id="webgl" width="500" height="1758"></canvas>

<script id="vertexShader" type="x-shader/x-vertex">
  attribute vec4 a_position;
  
  uniform mat4 u_modelViewMatrix;
  uniform mat4 u_projectionMatrix;
  
  void main() {
    gl_Position = a_position;
  }
</script>
<script id="fragmentShader" type="x-shader/x-fragment">
 precision highp float;
  precision highp int;
  
  uniform vec2 u_resolution;
  uniform vec2 u_mouse;
  uniform float u_time;
  uniform sampler2D u_noise;
  
  // movement variables
  vec3 movement = vec3(.0);
  
  const int maxIterations = 256;
  const float stopThreshold = 0.002;
  const float stepScale = .5;
  const float eps = 0.002;
  const vec3 clipColour = vec3(1.);
  const vec3 fogColour = vec3(1.);
  
  const vec3 light1_position = vec3(0, 1., -1.);
  const vec3 light1_colour = vec3(.8, .8, .85);
  
  struct Surface {
    int object_id;
    float distance;
    vec3 position;
    vec3 onsurface_position;
    vec3 colour;
    float steps;
    float ambient;
    float spec;
    float fog;
  };
  
  // Distance function copyright Inigo Quilez
  float opExtrusion( in vec3 p, in float primitive, in float h ) {
      float d = primitive;
      vec2 w = vec2( d, abs(p.z) - h );
      return min(max(w.x,w.y),0.0) + length(max(w,0.0));
  }
  float sdBox( in vec2 p, in vec2 b ) {
      vec2 d = abs(p)-b;
      return length(max(d,0.0)) + min(max(d.x,d.y),0.0);
  }
  
  vec3 path(float z) {
    // return vec3(0,0,0.);
    return vec3(sin(z * .1) * 4., sin(z * .05) * 10., z);
  }
  
  float getBlock(vec3 position, inout int object_id, inout vec3 p) {
    // position.z = fract(position.z) - .5;
    // object_id = int(id);
    float id = float(object_id);
    float r = sin(id * .3 + u_time) * .5;
    r = sin(texture2D(u_noise, vec2((id*2.)/255.)).x * 2. + u_time - id) * .25;
    float rw = texture2D(u_noise, vec2((id*2.)/255.)).x - .5;
    // // position.xy += r;
    float s = sin(r);
    float c = cos(r);
    position.xy *= mat2(c, -s, s, c);
    
    p = position;
    
    float box = sdBox(position.xy, vec2(1.5 + rw, 1.)) * -1.;
    float world = opExtrusion(position, box, .45) - .005;
    // world += smoothstep(.04, 0., abs(sin(p.x * 4.))) * .01;
    // world += smoothstep(.02, 0., abs(sin(p.y * 2.))) * .01;
    return world;
  }
  
  // This function describes the world in distances from any given 3 dimensional point in space
  float world(in vec3 position, inout int object_id, inout vec3 p) {
    
    position.xy -= path(position.z).xy;
    
    float id = floor(position.z);
    position.z = fract(position.z) - .5;
    
    int oid1 = int(id);
    vec3 p1;
    float block1 = getBlock(position, oid1, p1);
    int oid2 = int(id+1.);
    vec3 p2;
    float block2 = getBlock(position + vec3(0,0,-1), oid2, p2);
    
    object_id = oid1;
    p = p1;
    
    if(block2 < block1) {
      block1 = block2;
      object_id = oid2;
      p = p2;
    }
    
    return block1;
  }
  float world(in vec3 position, inout int object_id) {
    vec3 p;
    return world(position, object_id, p);
  }
  float world(in vec3 position) {
    int dummy = 0;
    return world(position, dummy);
  }
  
  Surface getSurface(int object_id, float rayDepth, vec3 sp, float steps, vec3 onsurface_pos, float fog) {
    return Surface(
      object_id, 
      rayDepth, 
      sp, 
      onsurface_pos,
      vec3(1.), 
      steps,
      .5, 
      1000.,
      fog);
  }
  
  // The raymarch loop
  Surface rayMarch(vec3 ro, vec3 rd, float start, float end) {
    float sceneDist = 1e4;
    float rayDepth = start;
    int object_id = 0;
    float steps = 0.;
    float fog = 0.;
    vec3 p;
    for(int i = 0; i < maxIterations; i++) {
      sceneDist = world(ro + rd * rayDepth, object_id, p);
      rd += (texture2D(u_noise, (p.xy)*255.).rgb-.5)*.0005;
      steps++;
      fog += max(sceneDist, 0.);
      
      if(sceneDist < stopThreshold || rayDepth > end) {
        break;
      }
      
      rayDepth += sceneDist * stepScale;
    }
    
    return getSurface(object_id, rayDepth, ro + rd * rayDepth, steps, p, fog);
  }
  
  // Calculated the normal of any given point in space. Intended to be cast from the point of a surface
  vec3 calculate_normal(in vec3 position) {
    vec3 grad = vec3(
      world(vec3(position.x + eps, position.y, position.z)) - world(vec3(position.x - eps, position.y, position.z)),
      world(vec3(position.x, position.y + eps, position.z)) - world(vec3(position.x, position.y - eps, position.z)),
      world(vec3(position.x, position.y, position.z + eps)) - world(vec3(position.x, position.y, position.z - eps))
    );
    
    return normalize(grad);
  }
  
  vec3 lighting(Surface surface_object, vec3 cam) {
    
    // start with black
    vec3 sceneColour = vec3(0);
    
    // Surface normal
    vec3 normal = calculate_normal(surface_object.position);
    normal += smoothstep(.02, 0., abs(sin(surface_object.onsurface_position.x * 4.))) * .5;
    normal += smoothstep(.01, 0., abs(sin(surface_object.onsurface_position.y * 2.))) * .5;
    
    // Light position
    vec3 lp = path(u_time*3.+15.);
    // Light direction
    vec3 ld = lp - surface_object.position;
    
    // light attenuation
    // For brightly lit scenes or global illumination (like sunlit), this can be limited to just normalizing the ld
    float len = length( ld );
    ld = normalize(ld);
    float lightAtten = min( 1.0 / ( 0.15*len ), 1.0 );
    lightAtten = 1.;
    
    // The surface's light reflection normal
    vec3 reflection_normal = reflect(-ld, normal);
    
    // Ambient Occlusion
    
    float ao = (surface_object.steps*.01*(1./(surface_object.fog*.07)));
    ao *= ao*2.;
    ao = clamp(
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