precision mediump float;
varying vec2 vTextureCoord;
uniform sampler2D uSampler;
void main() {
float screen_w = 100.0;
float screen_h = 100.0;
float rest_x = mod(gl_FragCoord.x + 1.0, screen_w);
float rest_y = mod(gl_FragCoord.y + 10.0, screen_h);
vec4 color = texture2D(uSampler, vTextureCoord);
bool line = (rest_x <= 0.5) || (rest_y <= 0.5);
// float alpha = line ? 0.1 : 0.0;
if (line) {
color.x = (color.x + 0.1) / 2.0;
color.y = (color.y + 0.1) / 2.0;
color.z = (color.z + 0.1) / 2.0;
}
gl_FragColor = vec4(
color.xyz, color.a);
}