使用 webgl 调用 p5.js 的 createcanvas 方法时出错

Question

我正在学习p5.js。

在本地测试 example below 时，

我收到以下错误：

这是我在本地测试的代码：

let flower = (p) => {
  let size, shading;

  p.setup = function() {
    let renderer = p.createCanvas(1024, 768, p.WEBGL);
    p.noStroke();

    size = p.min(p.width, p.height) / 3;
    shading = new p5.Shader(renderer, p.vert, p.frag);
    p.shader(shading);
    p.mouseX = p.width / 2;
    p.mouseY = p.height / 2;
  }

  p.draw = function() {
    p.background("#1a0633");
    p.orbitControl();
    p.rotateX(p.PI / 2);

    let time = p.millis() / 1000;
    shading.setUniform('iTime', time);
    shading.setUniform('size', size);
    shading.setUniform('mouse', [p.mouseX / p.width, p.mouseY / p.height]);
    p.plane(1, 1, 100, 100);
  }
};

let p5Flower = new p5(flower);

导致错误的原因是什么？

Answer 1

您还没有定义任何着色器

这个错误

表明 p.vert 没有设置任何值。

另外我很确定你想将 p.shader(shading) 从 setup 移动到 draw。它在示例中起作用的唯一原因是因为只有 1 个着色器。一旦有 2 个，它就会失败。但是，这不是您收到错误的原因。你收到一个错误，因为 p.vert 未定义。

const vert = `precision mediump float;
#define PI 3.14159265359
// our vertex data
attribute vec3 aPosition;
attribute vec2 aTexCoord;

//transform
uniform mat4 uModelViewMatrix;
uniform mat4 uProjectionMatrix;
uniform mat3 uNormalMatrix;

// lets get texcoords just for fun! 
varying vec2 vTexCoord;
varying float n;
uniform float iTime;
uniform vec2 mouse;
uniform float size;

// --- Simplex3D noise by Lallis/2015 https://www.shadertoy.com/view/XtBGDG
//http://webstaff.itn.liu.se/~stegu/simplexnoise/simplexnoise.pdf
//simplex pretty much 99% copied from there
//adjusted by getting "completely random" gradients instead of randoming from 12 preset ones
//and normalizing the gradient vector

float noise3D(vec3 p)
{
 return fract(sin(dot(p ,vec3(12.9898,78.233,128.852))) * 43758.5453)*2.0-1.0;
}

float simplex3D(vec3 p)
{
 
 float f3 = 1.0/3.0;
 float s = (p.x+p.y+p.z)*f3;
 int i = int(floor(p.x+s));
 int j = int(floor(p.y+s));
 int k = int(floor(p.z+s));
 
 float g3 = 1.0/6.0;
 float t = float((i+j+k))*g3;
 float x0 = float(i)-t;
 float y0 = float(j)-t;
 float z0 = float(k)-t;
 x0 = p.x-x0;
 y0 = p.y-y0;
 z0 = p.z-z0;
 
 int i1,j1,k1;
 int i2,j2,k2;
 
 if(x0>=y0)
 {
  if(y0>=z0){ i1=1; j1=0; k1=0; i2=1; j2=1; k2=0; } // X Y Z order
  else if(x0>=z0){ i1=1; j1=0; k1=0; i2=1; j2=0; k2=1; } // X Z Y order
  else { i1=0; j1=0; k1=1; i2=1; j2=0; k2=1; }  // Z X Z order
 }
 else 
 { 
  if(y0<z0) { i1=0; j1=0; k1=1; i2=0; j2=1; k2=1; } // Z Y X order
  else if(x0<z0) { i1=0; j1=1; k1=0; i2=0; j2=1; k2=1; } // Y Z X order
  else { i1=0; j1=1; k1=0; i2=1; j2=1; k2=0; } // Y X Z order
 }
 
 float x1 = x0 - float(i1) + g3; 
 float y1 = y0 - float(j1) + g3;
 float z1 = z0 - float(k1) + g3;
 float x2 = x0 - float(i2) + 2.0*g3; 
 float y2 = y0 - float(j2) + 2.0*g3;
 float z2 = z0 - float(k2) + 2.0*g3;
 float x3 = x0 - 1.0 + 3.0*g3; 
 float y3 = y0 - 1.0 + 3.0*g3;
 float z3 = z0 - 1.0 + 3.0*g3; 
     
 vec3 ijk0 = vec3(i,j,k);
 vec3 ijk1 = vec3(i+i1,j+j1,k+k1); 
 vec3 ijk2 = vec3(i+i2,j+j2,k+k2);
 vec3 ijk3 = vec3(i+1,j+1,k+1); 
            
 vec3 gr0 = normalize(vec3(noise3D(ijk0),noise3D(ijk0*2.01),noise3D(ijk0*2.02)));
 vec3 gr1 = normalize(vec3(noise3D(ijk1),noise3D(ijk1*2.01),noise3D(ijk1*2.02)));
 vec3 gr2 = normalize(vec3(noise3D(ijk2),noise3D(ijk2*2.01),noise3D(ijk2*2.02)));
 vec3 gr3 = normalize(vec3(noise3D(ijk3),noise3D(ijk3*2.01),noise3D(ijk3*2.02)));
 
 float n0 = 0.0;
 float n1 = 0.0;
 float n2 = 0.0;
 float n3 = 0.0;

 float t0 = 0.5 - x0*x0 - y0*y0 - z0*z0;
 if(t0>=0.0)
 {
  t0*=t0;
  n0 = t0 * t0 * dot(gr0, vec3(x0, y0, z0));
 }
 float t1 = 0.5 - x1*x1 - y1*y1 - z1*z1;
 if(t1>=0.0)
 {
  t1*=t1;
  n1 = t1 * t1 * dot(gr1, vec3(x1, y1, z1));
 }
 float t2 = 0.5 - x2*x2 - y2*y2 - z2*z2;
 if(t2>=0.0)
 {
  t2 *= t2;
  n2 = t2 * t2 * dot(gr2, vec3(x2, y2, z2));
 }
 float t3 = 0.5 - x3*x3 - y3*y3 - z3*z3;
 if(t3>=0.0)
 {
  t3 *= t3;
  n3 = t3 * t3 * dot(gr3, vec3(x3, y3, z3));
 }
 return 96.0*(n0+n1+n2+n3);
 
}

void main() {
  vTexCoord = aTexCoord;
  vec4 pos = vec4(aPosition, 1.0);
 n = simplex3D(vec3(iTime,pos.xy * 10.))*0.5+0.5;

 vec3 temp = pos.xyz;
 pos.x = cos(temp.x * PI * 10. * mouse.x) * (n+0.3) * size * (temp.y-mouse.y+0.5);
 pos.z = sin(temp.x * PI * 10. * mouse.x) * (n+0.3) * size * (temp.y-mouse.y+0.5);
 pos.y = pos.y * size * 3.;

  gl_Position = uProjectionMatrix * uModelViewMatrix * pos;
}`
const frag = `precision mediump float;
varying vec2 vTexCoord;
varying float n;
uniform float iTime;
void main()
{
 vec2 uv = vTexCoord;//*2.0-1.0;
 vec3 col = vec3(n*1.0, n*n*n*0.76, .2);
 gl_FragColor = vec4(col, 1.0);
}`


let flower = (p) => {
  let size, shading;

  p.setup = function() {
    let renderer = p.createCanvas(1024, 768, p.WEBGL);
    p.noStroke();
    size = p.min(p.width, p.height) / 3;
    shading = new p5.Shader(renderer, vert, frag);
    p.mouseX = p.width / 2;
    p.mouseY = p.height / 2;
  }

  p.draw = function() {
    p.background("#1a0633");
    p.orbitControl();
    p.rotateX(p.PI / 2);

    p.shader(shading);
    let time = p.millis() / 1000;
    shading.setUniform('iTime', time);
    shading.setUniform('size', size);
    shading.setUniform('mouse', [p.mouseX / p.width, p.mouseY / p.height]);
    p.plane(1, 1, 100, 100);
  }
};

let p5Flower = new p5(flower);

<script src="https://cdn.jsdelivr.net/npm/p5@0.10.2/lib/p5.js"></script>

使用 webgl 调用 p5.js 的 createcanvas 方法时出错

Error in calling createcanvas method of p5.js using webgl

javascript

webgl

vertex-shader

p5.js