Edge Falloff
A shader that creates a falloff effect on the edges of the screen.
#ifdef GL_ES
precision mediump float;
#define GLSLIFY 1
#endif
uniform vec2 u_resolution;
uniform float u_time;
uniform vec2 u_mouse;
#define GLSLIFY 1
void main() {
vec2 uv = gl_FragCoord.xy/u_resolution.xy;
//uv.x *= u_resolution.x/u_resolution.y;
uv=fract(uv*3.0);
//定義框
float L = smoothstep(0.1, 0.12, uv.x);
float B = smoothstep(0.1, 0.12, uv.y);
float R = smoothstep(0.1, 0.12, 1.-uv.x);
float T = smoothstep(0.1, 0.12, 1.-uv.y);
float rect = L*B*R*T; //黑顏料使用乘法, 白顏料使用加法
//vec2 uv2= uv*2.0-1.0;
//float rect2 = smoothstep(0.2, 0.29, abs(uv2.x))
//+smoothstep(0.6, 0.65, abs(uv2.y));
gl_FragColor = vec4(vec3(rect),1.0);
}