对于我的大学课程，我对Webgl很新，我什么都没学到。对于我们的家庭作业，我们必须编辑一些代码以将方块转换为六边形，我无法弄清楚从哪里开始以及如何理解代码中的顶点。我可以从哪里获得任何帮助。
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<title> Starting code for color hexagon assignment 2 </title>
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<script>// glMatrix v0.9.5
glMatrixArrayType=typeof Float32Array!="undefined"?Float32Array:typeof WebGLFloatArray!="undefined"?WebGLFloatArray:Array;var vec3={};vec3.create=function(a){var b=new glMatrixArrayType(3);if(a){b[0]=a[0];b[1]=a[1];b[2]=a[2]}return b};vec3.set=function(a,b){b[0]=a[0];b[1]=a[1];b[2]=a[2];return b};vec3.add=function(a,b,c){if(!c||a==c){a[0]+=b[0];a[1]+=b[1];a[2]+=b[2];return a}c[0]=a[0]+b[0];c[1]=a[1]+b[1];c[2]=a[2]+b[2];return c};
vec3.subtract=function(a,b,c){if(!c||a==c){a[0]-=b[0];a[1]-=b[1];a[2]-=b[2];return a}c[0]=a[0]-b[0];c[1]=a[1]-b[1];c[2]=a[2]-b[2];return c};vec3.negate=function(a,b){b||(b=a);b[0]=-a[0];b[1]=-a[1];b[2]=-a[2];return b};vec3.scale=function(a,b,c){if(!c||a==c){a[0]*=b;a[1]*=b;a[2]*=b;return a}c[0]=a[0]*b;c[1]=a[1]*b;c[2]=a[2]*b;return c};
vec3.normalize=function(a,b){b||(b=a);var c=a[0],d=a[1],e=a[2],g=Math.sqrt(c*c+d*d+e*e);if(g){if(g==1){b[0]=c;b[1]=d;b[2]=e;return b}}else{b[0]=0;b[1]=0;b[2]=0;return b}g=1/g;b[0]=c*g;b[1]=d*g;b[2]=e*g;return b};vec3.cross=function(a,b,c){c||(c=a);var d=a[0],e=a[1];a=a[2];var g=b[0],f=b[1];b=b[2];c[0]=e*b-a*f;c[1]=a*g-d*b;c[2]=d*f-e*g;return c};vec3.length=function(a){var b=a[0],c=a[1];a=a[2];return Math.sqrt(b*b+c*c+a*a)};vec3.dot=function(a,b){return a[0]*b[0]+a[1]*b[1]+a[2]*b[2]};
vec3.direction=function(a,b,c){c||(c=a);var d=a[0]-b[0],e=a[1]-b[1];a=a[2]-b[2];b=Math.sqrt(d*d+e*e+a*a);if(!b){c[0]=0;c[1]=0;c[2]=0;return c}b=1/b;c[0]=d*b;c[1]=e*b;c[2]=a*b;return c};vec3.lerp=function(a,b,c,d){d||(d=a);d[0]=a[0]+c*(b[0]-a[0]);d[1]=a[1]+c*(b[1]-a[1]);d[2]=a[2]+c*(b[2]-a[2]);return d};vec3.str=function(a){return"["+a[0]+", "+a[1]+", "+a[2]+"]"};var mat3={};
mat3.create=function(a){var b=new glMatrixArrayType(9);if(a){b[0]=a[0];b[1]=a[1];b[2]=a[2];b[3]=a[3];b[4]=a[4];b[5]=a[5];b[6]=a[6];b[7]=a[7];b[8]=a[8];b[9]=a[9]}return b};mat3.set=function(a,b){b[0]=a[0];b[1]=a[1];b[2]=a[2];b[3]=a[3];b[4]=a[4];b[5]=a[5];b[6]=a[6];b[7]=a[7];b[8]=a[8];return b};mat3.identity=function(a){a[0]=1;a[1]=0;a[2]=0;a[3]=0;a[4]=1;a[5]=0;a[6]=0;a[7]=0;a[8]=1;return a};
mat3.transpose=function(a,b){if(!b||a==b){var c=a[1],d=a[2],e=a[5];a[1]=a[3];a[2]=a[6];a[3]=c;a[5]=a[7];a[6]=d;a[7]=e;return a}b[0]=a[0];b[1]=a[3];b[2]=a[6];b[3]=a[1];b[4]=a[4];b[5]=a[7];b[6]=a[2];b[7]=a[5];b[8]=a[8];return b};mat3.toMat4=function(a,b){b||(b=mat4.create());b[0]=a[0];b[1]=a[1];b[2]=a[2];b[3]=0;b[4]=a[3];b[5]=a[4];b[6]=a[5];b[7]=0;b[8]=a[6];b[9]=a[7];b[10]=a[8];b[11]=0;b[12]=0;b[13]=0;b[14]=0;b[15]=1;return b};
mat3.str=function(a){return"["+a[0]+", "+a[1]+", "+a[2]+", "+a[3]+", "+a[4]+", "+a[5]+", "+a[6]+", "+a[7]+", "+a[8]+"]"};var mat4={};mat4.create=function(a){var b=new glMatrixArrayType(16);if(a){b[0]=a[0];b[1]=a[1];b[2]=a[2];b[3]=a[3];b[4]=a[4];b[5]=a[5];b[6]=a[6];b[7]=a[7];b[8]=a[8];b[9]=a[9];b[10]=a[10];b[11]=a[11];b[12]=a[12];b[13]=a[13];b[14]=a[14];b[15]=a[15]}return b};
mat4.set=function(a,b){b[0]=a[0];b[1]=a[1];b[2`enter code here`]=a[2];b[3]=a[3];b[4]=a[4];b[5]=a[5];b[6]=a[6];b[7]=a[7];b[8]=a[8];b[9]=a[9];b[10]=a[10];b[11]=a[11];b[12]=a[12];b[13]=a[13];b[14]=a[14];b[15]=a[15];return b};mat4.identity=function(a){a[0]=1;a[1]=0;a[2]=0;a[3]=0;a[4]=0;a[5]=1;a[6]=0;a[7]=0;a[8]=0;a[9]=0;a[10]=1;a[11]=0;a[12]=0;a[13]=0;a[14]=0;a[15]=1;return a};
mat4.transpose=function(a,b){if(!b||a==b){var c=a[1],d=a[2],e=a[3],g=a[6],f=a[7],h=a[11];a[1]=a[4];a[2]=a[8];a[3]=a[12];a[4]=c;a[6]=a[9];a[7]=a[13];a[8]=d;a[9]=g;a[11]=a[14];a[12]=e;a[13]=f;a[14]=h;return a}b[0]=a[0];b[1]=a[4];b[2]=a[8];b[3]=a[12];b[4]=a[1];b[5]=a[5];b[6]=a[9];b[7]=a[13];b[8]=a[2];b[9]=a[6];b[10]=a[10];b[11]=a[14];b[12]=a[3];b[13]=a[7];b[14]=a[11];b[15]=a[15];return b};
mat4.determinant=function(a){var b=a[0],c=a[1],d=a[2],e=a[3],g=a[4],f=a[5],h=a[6],i=a[7],j=a[8],k=a[9],l=a[10],o=a[11],m=a[12],n=a[13],p=a[14];a=a[15];return m*k*h*e-j*n*h*e-m*f*l*e+g*n*l*e+j*f*p*e-g*k*p*e-m*k*d*i+j*n*d*i+m*c*l*i-b*n*l*i-j*c*p*i+b*k*p*i+m*f*d*o-g*n*d*o-m*c*h*o+b*n*h*o+g*c*p*o-b*f*p*o-j*f*d*a+g*k*d*a+j*c*h*a-b*k*h*a-g*c*l*a+b*f*l*a};
mat4.inverse=function(a,b){b||(b=a);var c=a[0],d=a[1],e=a[2],g=a[3],f=a[4],h=a[5],i=a[6],j=a[7],k=a[8],l=a[9],o=a[10],m=a[11],n=a[12],p=a[13],r=a[14],s=a[15],A=c*h-d*f,B=c*i-e*f,t=c*j-g*f,u=d*i-e*h,v=d*j-g*h,w=e*j-g*i,x=k*p-l*n,y=k*r-o*n,z=k*s-m*n,C=l*r-o*p,D=l*s-m*p,E=o*s-m*r,q=1/(A*E-B*D+t*C+u*z-v*y+w*x);b[0]=(h*E-i*D+j*C)*q;b[1]=(-d*E+e*D-g*C)*q;b[2]=(p*w-r*v+s*u)*q;b[3]=(-l*w+o*v-m*u)*q;b[4]=(-f*E+i*z-j*y)*q;b[5]=(c*E-e*z+g*y)*q;b[6]=(-n*w+r*t-s*B)*q;b[7]=(k*w-o*t+m*B)*q;b[8]=(f*D-h*z+j*x)*q;
b[9]=(-c*D+d*z-g*x)*q;b[10]=(n*v-p*t+s*A)*q;b[11]=(-k*v+l*t-m*A)*q;b[12]=(-f*C+h*y-i*x)*q;b[13]=(c*C-d*y+e*x)*q;b[14]=(-n*u+p*B-r*A)*q;b[15]=(k*u-l*B+o*A)*q;return b};mat4.toRotationMat=function(a,b){b||(b=mat4.create());b[0]=a[0];b[1]=a[1];b[2]=a[2];b[3]=a[3];b[4]=a[4];b[5]=a[5];b[6]=a[6];b[7]=a[7];b[8]=a[8];b[9]=a[9];b[10]=a[10];b[11]=a[11];b[12]=0;b[13]=0;b[14]=0;b[15]=1;return b};
mat4.toMat3=function(a,b){b||(b=mat3.create());b[0]=a[0];b[1]=a[1];b[2]=a[2];b[3]=a[4];b[4]=a[5];b[5]=a[6];b[6]=a[8];b[7]=a[9];b[8]=a[10];return b};mat4.toInverseMat3=function(a,b){var c=a[0],d=a[1],e=a[2],g=a[4],f=a[5],h=a[6],i=a[8],j=a[9],k=a[10],l=k*f-h*j,o=-k*g+h*i,m=j*g-f*i,n=c*l+d*o+e*m;if(!n)return null;n=1/n;b||(b=mat3.create());b[0]=l*n;b[1]=(-k*d+e*j)*n;b[2]=(h*d-e*f)*n;b[3]=o*n;b[4]=(k*c-e*i)*n;b[5]=(-h*c+e*g)*n;b[6]=m*n;b[7]=(-j*c+d*i)*n;b[8]=(f*c-d*g)*n;return b};
mat4.multiply=function(a,b,c){c||(c=a);var d=a[0],e=a[1],g=a[2],f=a[3],h=a[4],i=a[5],j=a[6],k=a[7],l=a[8],o=a[9],m=a[10],n=a[11],p=a[12],r=a[13],s=a[14];a=a[15];var A=b[0],B=b[1],t=b[2],u=b[3],v=b[4],w=b[5],x=b[6],y=b[7],z=b[8],C=b[9],D=b[10],E=b[11],q=b[12],F=b[13],G=b[14];b=b[15];c[0]=A*d+B*h+t*l+u*p;c[1]=A*e+B*i+t*o+u*r;c[2]=A*g+B*j+t*m+u*s;c[3]=A*f+B*k+t*n+u*a;c[4]=v*d+w*h+x*l+y*p;c[5]=v*e+w*i+x*o+y*r;c[6]=v*g+w*j+x*m+y*s;c[7]=v*f+w*k+x*n+y*a;c[8]=z*d+C*h+D*l+E*p;c[9]=z*e+C*i+D*o+E*r;c[10]=z*
g+C*j+D*m+E*s;c[11]=z*f+C*k+D*n+E*a;c[12]=q*d+F*h+G*l+b*p;c[13]=q*e+F*i+G*o+b*r;c[14]=q*g+F*j+G*m+b*s;c[15]=q*f+F*k+G*n+b*a;return c};mat4.multiplyVec3=function(a,b,c){c||(c=b);var d=b[0],e=b[1];b=b[2];c[0]=a[0]*d+a[4]*e+a[8]*b+a[12];c[1]=a[1]*d+a[5]*e+a[9]*b+a[13];c[2]=a[2]*d+a[6]*e+a[10]*b+a[14];return c};
mat4.multiplyVec4=function(a,b,c){c||(c=b);var d=b[0],e=b[1],g=b[2];b=b[3];c[0]=a[0]*d+a[4]*e+a[8]*g+a[12]*b;c[1]=a[1]*d+a[5]*e+a[9]*g+a[13]*b;c[2]=a[2]*d+a[6]*e+a[10]*g+a[14]*b;c[3]=a[3]*d+a[7]*e+a[11]*g+a[15]*b;return c};
mat4.translate=function(a,b,c){var d=b[0],e=b[1];b=b[2];if(!c||a==c){a[12]=a[0]*d+a[4]*e+a[8]*b+a[12];a[13]=a[1]*d+a[5]*e+a[9]*b+a[13];a[14]=a[2]*d+a[6]*e+a[10]*b+a[14];a[15]=a[3]*d+a[7]*e+a[11]*b+a[15];return a}var g=a[0],f=a[1],h=a[2],i=a[3],j=a[4],k=a[5],l=a[6],o=a[7],m=a[8],n=a[9],p=a[10],r=a[11];c[0]=g;c[1]=f;c[2]=h;c[3]=i;c[4]=j;c[5]=k;c[6]=l;c[7]=o;c[8]=m;c[9]=n;c[10]=p;c[11]=r;c[12]=g*d+j*e+m*b+a[12];c[13]=f*d+k*e+n*b+a[13];c[14]=h*d+l*e+p*b+a[14];c[15]=i*d+o*e+r*b+a[15];return c};
mat4.scale=function(a,b,c){var d=b[0],e=b[1];b=b[2];if(!c||a==c){a[0]*=d;a[1]*=d;a[2]*=d;a[3]*=d;a[4]*=e;a[5]*=e;a[6]*=e;a[7]*=e;a[8]*=b;a[9]*=b;a[10]*=b;a[11]*=b;return a}c[0]=a[0]*d;c[1]=a[1]*d;c[2]=a[2]*d;c[3]=a[3]*d;c[4]=a[4]*e;c[5]=a[5]*e;c[6]=a[6]*e;c[7]=a[7]*e;c[8]=a[8]*b;c[9]=a[9]*b;c[10]=a[10]*b;c[11]=a[11]*b;c[12]=a[12];c[13]=a[13];c[14]=a[14];c[15]=a[15];return c};
mat4.rotate=function(a,b,c,d){var e=c[0],g=c[1];c=c[2];var f=Math.sqrt(e*e+g*g+c*c);if(!f)return null;if(f!=1){f=1/f;e*=f;g*=f;c*=f}var h=Math.sin(b),i=Math.cos(b),j=1-i;b=a[0];f=a[1];var k=a[2],l=a[3],o=a[4],m=a[5],n=a[6],p=a[7],r=a[8],s=a[9],A=a[10],B=a[11],t=e*e*j+i,u=g*e*j+c*h,v=c*e*j-g*h,w=e*g*j-c*h,x=g*g*j+i,y=c*g*j+e*h,z=e*c*j+g*h;e=g*c*j-e*h;g=c*c*j+i;if(d){if(a!=d){d[12]=a[12];d[13]=a[13];d[14]=a[14];d[15]=a[15]}}else d=a;d[0]=b*t+o*u+r*v;d[1]=f*t+m*u+s*v;d[2]=k*t+n*u+A*v;d[3]=l*t+p*u+B*
v;d[4]=b*w+o*x+r*y;d[5]=f*w+m*x+s*y;d[6]=k*w+n*x+A*y;d[7]=l*w+p*x+B*y;d[8]=b*z+o*e+r*g;d[9]=f*z+m*e+s*g;d[10]=k*z+n*e+A*g;d[11]=l*z+p*e+B*g;return d};mat4.rotateX=function(a,b,c){var d=Math.sin(b);b=Math.cos(b);var e=a[4],g=a[5],f=a[6],h=a[7],i=a[8],j=a[9],k=a[10],l=a[11];if(c){if(a!=c){c[0]=a[0];c[1]=a[1];c[2]=a[2];c[3]=a[3];c[12]=a[12];c[13]=a[13];c[14]=a[14];c[15]=a[15]}}else c=a;c[4]=e*b+i*d;c[5]=g*b+j*d;c[6]=f*b+k*d;c[7]=h*b+l*d;c[8]=e*-d+i*b;c[9]=g*-d+j*b;c[10]=f*-d+k*b;c[11]=h*-d+l*b;return c};
mat4.rotateY=function(a,b,c){var d=Math.sin(b);b=Math.cos(b);var e=a[0],g=a[1],f=a[2],h=a[3],i=a[8],j=a[9],k=a[10],l=a[11];if(c){if(a!=c){c[4]=a[4];c[5]=a[5];c[6]=a[6];c[7]=a[7];c[12]=a[12];c[13]=a[13];c[14]=a[14];c[15]=a[15]}}else c=a;c[0]=e*b+i*-d;c[1]=g*b+j*-d;c[2]=f*b+k*-d;c[3]=h*b+l*-d;c[8]=e*d+i*b;c[9]=g*d+j*b;c[10]=f*d+k*b;c[11]=h*d+l*b;return c};
mat4.rotateZ=function(a,b,c){var d=Math.sin(b);b=Math.cos(b);var e=a[0],g=a[1],f=a[2],h=a[3],i=a[4],j=a[5],k=a[6],l=a[7];if(c){if(a!=c){c[8]=a[8];c[9]=a[9];c[10]=a[10];c[11]=a[11];c[12]=a[12];c[13]=a[13];c[14]=a[14];c[15]=a[15]}}else c=a;c[0]=e*b+i*d;c[1]=g*b+j*d;c[2]=f*b+k*d;c[3]=h*b+l*d;c[4]=e*-d+i*b;c[5]=g*-d+j*b;c[6]=f*-d+k*b;c[7]=h*-d+l*b;return c};
mat4.frustum=function(a,b,c,d,e,g,f){f||(f=mat4.create());var h=b-a,i=d-c,j=g-e;f[0]=e*2/h;f[1]=0;f[2]=0;f[3]=0;f[4]=0;f[5]=e*2/i;f[6]=0;f[7]=0;f[8]=(b+a)/h;f[9]=(d+c)/i;f[10]=-(g+e)/j;f[11]=-1;f[12]=0;f[13]=0;f[14]=-(g*e*2)/j;f[15]=0;return f};mat4.perspective=function(a,b,c,d,e){a=c*Math.tan(a*Math.PI/360);b=a*b;return mat4.frustum(-b,b,-a,a,c,d,e)};
mat4.ortho=function(a,b,c,d,e,g,f){f||(f=mat4.create());var h=b-a,i=d-c,j=g-e;f[0]=2/h;f[1]=0;f[2]=0;f[3]=0;f[4]=0;f[5]=2/i;f[6]=0;f[7]=0;f[8]=0;f[9]=0;f[10]=-2/j;f[11]=0;f[12]=-(a+b)/h;f[13]=-(d+c)/i;f[14]=-(g+e)/j;f[15]=1;return f};
mat4.lookAt=function(a,b,c,d){d||(d=mat4.create());var e=a[0],g=a[1];a=a[2];var f=c[0],h=c[1],i=c[2];c=b[1];var j=b[2];if(e==b[0]&&g==c&&a==j)return mat4.identity(d);var k,l,o,m;c=e-b[0];j=g-b[1];b=a-b[2];m=1/Math.sqrt(c*c+j*j+b*b);c*=m;j*=m;b*=m;k=h*b-i*j;i=i*c-f*b;f=f*j-h*c;if(m=Math.sqrt(k*k+i*i+f*f)){m=1/m;k*=m;i*=m;f*=m}else f=i=k=0;h=j*f-b*i;l=b*k-c*f;o=c*i-j*k;if(m=Math.sqrt(h*h+l*l+o*o)){m=1/m;h*=m;l*=m;o*=m}else o=l=h=0;d[0]=k;d[1]=h;d[2]=c;d[3]=0;d[4]=i;d[5]=l;d[6]=j;d[7]=0;d[8]=f;d[9]=
o;d[10]=b;d[11]=0;d[12]=-(k*e+i*g+f*a);d[13]=-(h*e+l*g+o*a);d[14]=-(c*e+j*g+b*a);d[15]=1;return d};mat4.str=function(a){return"["+a[0]+", "+a[1]+", "+a[2]+", "+a[3]+", "+a[4]+", "+a[5]+", "+a[6]+", "+a[7]+", "+a[8]+", "+a[9]+", "+a[10]+", "+a[11]+", "+a[12]+", "+a[13]+", "+a[14]+", "+a[15]+"]"};quat4={};quat4.create=function(a){var b=new glMatrixArrayType(4);if(a){b[0]=a[0];b[1]=a[1];b[2]=a[2];b[3]=a[3]}return b};quat4.set=function(a,b){b[0]=a[0];b[1]=a[1];b[2]=a[2];b[3]=a[3];return b};
quat4.calculateW=function(a,b){var c=a[0],d=a[1],e=a[2];if(!b||a==b){a[3]=-Math.sqrt(Math.abs(1-c*c-d*d-e*e));return a}b[0]=c;b[1]=d;b[2]=e;b[3]=-Math.sqrt(Math.abs(1-c*c-d*d-e*e));return b};quat4.inverse=function(a,b){if(!b||a==b){a[0]*=1;a[1]*=1;a[2]*=1;return a}b[0]=-a[0];b[1]=-a[1];b[2]=-a[2];b[3]=a[3];return b};quat4.length=function(a){var b=a[0],c=a[1],d=a[2];a=a[3];return Math.sqrt(b*b+c*c+d*d+a*a)};
quat4.normalize=function(a,b){b||(b=a);var c=a[0],d=a[1],e=a[2],g=a[3],f=Math.sqrt(c*c+d*d+e*e+g*g);if(f==0){b[0]=0;b[1]=0;b[2]=0;b[3]=0;return b}f=1/f;b[0]=c*f;b[1]=d*f;b[2]=e*f;b[3]=g*f;return b};quat4.multiply=function(a,b,c){c||(c=a);var d=a[0],e=a[1],g=a[2];a=a[3];var f=b[0],h=b[1],i=b[2];b=b[3];c[0]=d*b+a*f+e*i-g*h;c[1]=e*b+a*h+g*f-d*i;c[2]=g*b+a*i+d*h-e*f;c[3]=a*b-d*f-e*h-g*i;return c};
quat4.multiplyVec3=function(a,b,c){c||(c=b);var d=b[0],e=b[1],g=b[2];b=a[0];var f=a[1],h=a[2];a=a[3];var i=a*d+f*g-h*e,j=a*e+h*d-b*g,k=a*g+b*e-f*d;d=-b*d-f*e-h*g;c[0]=i*a+d*-b+j*-h-k*-f;c[1]=j*a+d*-f+k*-b-i*-h;c[2]=k*a+d*-h+i*-f-j*-b;return c};quat4.toMat3=function(a,b){b||(b=mat3.create());var c=a[0],d=a[1],e=a[2],g=a[3],f=c+c,h=d+d,i=e+e,j=c*f,k=c*h;c=c*i;var l=d*h;d=d*i;e=e*i;f=g*f;h=g*h;g=g*i;b[0]=1-(l+e);b[1]=k-g;b[2]=c+h;b[3]=k+g;b[4]=1-(j+e);b[5]=d-f;b[6]=c-h;b[7]=d+f;b[8]=1-(j+l);return b};
quat4.toMat4=function(a,b){b||(b=mat4.create());var c=a[0],d=a[1],e=a[2],g=a[3],f=c+c,h=d+d,i=e+e,j=c*f,k=c*h;c=c*i;var l=d*h;d=d*i;e=e*i;f=g*f;h=g*h;g=g*i;b[0]=1-(l+e);b[1]=k-g;b[2]=c+h;b[3]=0;b[4]=k+g;b[5]=1-(j+e);b[6]=d-f;b[7]=0;b[8]=c-h;b[9]=d+f;b[10]=1-(j+l);b[11]=0;b[12]=0;b[13]=0;b[14]=0;b[15]=1;return b};quat4.slerp=function(a,b,c,d){d||(d=a);var e=c;if(a[0]*b[0]+a[1]*b[1]+a[2]*b[2]+a[3]*b[3]<0)e=-1*c;d[0]=1-c*a[0]+e*b[0];d[1]=1-c*a[1]+e*b[1];d[2]=1-c*a[2]+e*b[2];d[3]=1-c*a[3]+e*b[3];return d};
quat4.str=function(a){return"["+a[0]+", "+a[1]+", "+a[2]+", "+a[3]+"]"};</script>
<script id="frag_shader" type="x-shader/x-fragment">
precision mediump float;
varying vec4 Color;
void main(void) {
gl_FragColor = Color;
}
</script>
<script id="vert-shader" type="x-shader/x-vertex">
attribute vec3 VertexPosition;
attribute vec4 VertexColor;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
varying vec4 Color;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(VertexPosition, 1.0);
Color = VertexColor;
}
</script>
<script type="text/javascript">
var gl;
function initGL(canvas) {
try {
gl = canvas.getContext("webgl");
gl.viewportWidth = canvas.width;
gl.viewportHeight = canvas.height;
} catch (e) {
}
if (!gl) {
alert("Could not initialise WebGL, sorry :-(");
}
}
function getShader(gl, id) {
var shaderScript = document.getElementById(id);
if (!shaderScript) {
return null;
}
var str = "";
var k = shaderScript.firstChild;
while (k) {
if (k.nodeType == 3) {
str += k.textContent;
}
k = k.nextSibling;
}
var shader;
if (shaderScript.type == "x-shader/x-fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (shaderScript.type == "x-shader/x-vertex") {
shader = gl.createShader(gl.VERTEX_SHADER);
} else {
return null;
}
gl.shaderSource(shader, str);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert(gl.getShaderInfoLog(shader));
return null;
}
return shader;
}
var shaderProgram;
function initShaders() {
var fragmentShader = getShader(gl, "frag_shader");
var vertexShader = getShader(gl, "vert-shader");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "VertexPosition");
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
shaderProgram.vertexColorAttribute = gl.getAttribLocation(shaderProgram, "VertexColor");
gl.enableVertexAttribArray(shaderProgram.vertexColorAttribute);
shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
}
var mvMatrix = mat4.create();
var pMatrix = mat4.create();
function setMatrixUniforms() {
gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
}
var triangleVertexPositionBuffer;
var triangleVertexColorBuffer;
var squareVertexPositionBuffer;
var squareVertexColorBuffer;
function initBuffers() {
triangleVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer);
var vertices = [
0.0, 1.0, 0.0,
-1.0, -1.0, 0.0,
1.0, -1.0, 0.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
triangleVertexPositionBuffer.itemSize = 3;
triangleVertexPositionBuffer.numItems = 3;
triangleVertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexColorBuffer);
var colors = [
1.0, 0.0, 0.0, 1.0,
0.0, 1.0, 0.0, 1.0,
0.0, 0.0, 1.0, 1.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
triangleVertexColorBuffer.itemSize = 4;
triangleVertexColorBuffer.numItems = 3;
// XXX asn 2 discussed in class: change the square to a colored hexagon
squareVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
vertices = [
1.0-.5, 1.0, .0,
-1.0-.5, 1.0, .0,
1.0-.5, -1.0, .0,
-1.0-.5, -1.0, .0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
squareVertexPositionBuffer.itemSize = 3;
squareVertexPositionBuffer.numItems = 4;
squareVertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexColorBuffer);
colors = [];
for (var i=0; i < 4; i++) {
colors = colors.concat([0.5*i, 1-0.5*i, 1*(i&1), 1.0]);
}
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW);
squareVertexColorBuffer.itemSize = 4;
squareVertexColorBuffer.numItems = 4;
}
function drawScene() {
gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT);
mat4.perspective(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0, pMatrix);
mat4.identity(mvMatrix);
mat4.translate(mvMatrix, [-1.5, 0.0, -4.0]);
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, triangleVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, triangleVertexColorBuffer);
gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, triangleVertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);
setMatrixUniforms();
gl.drawArrays(gl.TRIANGLES, 0, triangleVertexPositionBuffer.numItems);
mat4.translate(mvMatrix, [3.0, 0.0, 0.0]);
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, squareVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexColorBuffer);
gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, squareVertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);
setMatrixUniforms();
gl.drawArrays(gl.TRIANGLE_FAN, 0, squareVertexPositionBuffer.numItems);
}
function begin_WebGL() {
var canvas = document.getElementById("canvas");
initGL(canvas);
initShaders();
initBuffers();
gl.clearColor(0, 0, 0, 1);
//gl.enable(gl.DEPTH_TEST);
drawScene();
}
</script>
</head>
<body onload="begin_WebGL();">
<canvas id="canvas" style="border: none;" width="800" height="480"></canvas>
</body>`enter code here`
</html>
答案 0 :(得分：3)
我不想放弃分配（因为.....）的解决方案，但你可以将它作为一个提升：正如你所看到的，这里是顶点上面的来源：
// XXX asn 2 discussed in class: change the square to a colored hexagon
squareVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, squareVertexPositionBuffer);
vertices = [
1.0-.5, 1.0, .0,
-1.0-.5, 1.0, .0,
1.0-.5, -1.0, .0,
-1.0-.5, -1.0, .0
];
顶点是坐标（x，y，z）。 0, 0, 0应该是对象的中心。 -.5很奇怪，应该删除。
您需要绘制多个三角形。为此使用三角形风扇。你应该读这个：GL_TRIANGLE FAN Explanation
所以你需要指定类似的东西：
B---C
/ \ / \
G---A---D
\ / \ /
F---E
六边形有7 + 1个顶点。 A-B-C-D-E-F-G-B（最后一个连接G和B）
它将创建这些三角形：
提示：注意：
之间的区别 gl.drawArrays(-> gl.TRIANGLES <-, 0, triangleVertexPositionBuffer.numItems);和
gl.drawArrays(-> gl.TRIANGLE_FAN <-, 0, squareVertexPositionBuffer.numItems);
（上一个）方格被定义为：
A--B
|\ |
| \|
D--C
您可以使用sin / cos，半径和边数来计算它们，而不是指定坐标。
这样您就可以创建许多基本的几何形状