javascript - 使用webgl调用p5.js的createcanvas方法出错

Question

我正在学习p5.js .

测试 example below 时本地，

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);

什么原因导致错误？

Answer 1

您尚未定义任何着色器

这个错误

表明p.vert未设置任何内容。

而且我很确定您想将 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个就会失败。但是，这不是您收到错误的原因。您收到错误是因为 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>