vec2 st = gl_FragCoord.xy/u_resolution.xy; //将绘图区的坐标归一到 0.0~0.1 http://cesium.xin/wordpress/archives/webgl-basic-knowladge.html
vec4 color = texture2D(u_texture_1,st); // 读取纹理

你看一下之前的文章

uniform vec2 u_resolution;
uniform sampler2D u_texture_1;

void main(){
vec2 st = gl_FragCoord.xy/u_resolution.xy;
vec4 color = texture2D(u_texture_1,st);
gl_FragColor = color;
}

想麻烦你这边讲一下这段代码的含义，我在settings.json中配置了图片，可是没有效果