如何修复此体积光着色器

Question

im试图对球体实施某种光圈效应。这个想法是，它似乎是沿着法向矢量的方向以体积方式发光。但我不知道该怎么办。

我的片段着色器就是这样，我实现了“径向”模糊，并且它只能在相机面向球面的情况下正常工作。

如果不是，就会发生这种情况；

我试图遵循此示例，但没有成功：

https://medium.com/@andrew_b_berg/volumetric-light-scattering-in-three-js-6e1850680a41

这就是我想要得到的：

这是我的代码：

import controlP5.*;

ControlP5 cp5;
import peasy.*;

PGraphics canvas;

PGraphics verticalBlurPass;

PShader blurFilter;
PeasyCam cam;


void setup()
{
  cam = new PeasyCam(this, 1400);
  size(1000, 1000, P3D);



  canvas = createGraphics(width, height, P3D);


  verticalBlurPass = createGraphics(width, height, P3D);
  verticalBlurPass.noSmooth(); 

  blurFilter = loadShader("bloomFrag.glsl", "blurVert.glsl");
}

void draw(){
  background(0);

  canvas.beginDraw();
  render(canvas);
  canvas.endDraw();

  // blur vertical pass
  verticalBlurPass.beginDraw();
  verticalBlurPass.shader(blurFilter);
  verticalBlurPass.image(canvas, 0, 0);
  //render(verticalBlurPass);
  verticalBlurPass.endDraw();

  cam.beginHUD();

  image(verticalBlurPass, 0, 0);

  cam.endHUD();

println(frameRate);
}

void render(PGraphics pg)
{
  cam.getState().apply(pg);

  pg.background(0, 50);
  pg.stroke(255, 0, 0);



      canvas.fill(100, 0, 255);
      canvas.fill(255);

      pg.noStroke();
    canvas.sphere(100);
    pg.noFill();
     pg.stroke(255);
    pg.strokeWeight(10);


}

顶点：

#version 150

   in vec4 position;
   in vec3 normal;

   uniform mat4 transform;

   in vec2 texCoord;
   out vec4 TexCoord;

   in vec3 color;
  out vec3 Color;


  uniform float u_time;
  uniform mat4 texMatrix;


    void main() {
Color = color;

    TexCoord = texMatrix * vec4(texCoord, 1.0, 1.0);
        gl_Position = transform * position ;
    }

片段：

#version 150
#define PROCESSING_TEXTURE_SHADER
#ifdef GL_ES
precision mediump float;
#endif
in vec4 TexCoord;
in vec3 Color;
uniform sampler2D texture;
uniform float u_time;
uniform float amt;
uniform float intensity;
uniform float x;
uniform float y;
uniform float noiseAmt;
uniform float u_time2;
out mediump vec4 fragColor;
vec4 finalColor;
#define PI  3.14


uniform vec2 lightPosition = vec2(0,0);
uniform float exposure = 0.09;
uniform float decay = .95;
uniform float density = 1.0;

uniform float weight = 1;
uniform int samples = 100;
const int MAX_SAMPLES = 100;


uniform vec2 resolution; // screen resolution

void main(){

  vec2 texCoord = TexCoord.xy;
  // Calculate vector from pixel to light source in screen space
  vec2 deltaTextCoord = texCoord - lightPosition;
  // Divide by number of samples and scale by control factor
  deltaTextCoord *= 1.0 / float(samples) * density;
  // Store initial sample
  vec4 color = texture(texture, texCoord);
  // set up illumination decay factor
  float illuminationDecay = 1.0;

  // evaluate the summation for samples number of iterations up to 100
  for(int i=0; i < MAX_SAMPLES; i++){
    // work around for dynamic number of loop iterations
    if(i == samples){
      break;
    }

    // step sample location along ray
    texCoord -= deltaTextCoord;
    // retrieve sample at new location
    vec4 color2 = texture(texture, texCoord);
    // apply sample attenuation scale/decay factors
    color2 *= illuminationDecay * weight;
    // accumulate combined color
    color += color2;
    // update exponential decay factor
    illuminationDecay *= decay;

  }
  // output final color with a further scale control factor
  fragColor = color * exposure;
}

有什么想法吗？我在做什么错了？