` uniform sampler2D uSampler; varying highp vec2 vTextureCoord; varying highp vec3 vLighting; // Why it is necessary to set precission for the fragment shader? //Vertex shader works without this, but fragment shader //doesn't work without this code row (as I see). //Why the different behaviour exist? void main() { highp vec4 texelColor = texture2D(uSampler, vTextureCoord); gl_FragColor = vec4(texelColor.rgb * vLighting, texelColor.a); // gl_FragColor = mix ( vColor , texture2D(uSampler, vTextureCoord), 0.6 ); // gl_FragColor = texture2D(uSampler, vTextureCoord); // gl_FragColor == vec4(1.0 , 1.0 , 1.0 , 1.0 ) ; }`