1_2_bilerp

Code 1.3, Figure 1.4:

1_2_bilerp.frag

#version 300 es precision highp float; out vec4 fragColor; uniform float u_time; uniform vec2 u_resolution; void main(){ vec2 pos = gl_FragCoord.xy / u_resolution.xy; vec3[4] col4 = vec3[]( vec3(1.0, 0.0, 0.0), vec3(0.0, 0.0, 1.0), vec3(0.0, 1.0, 0.0), vec3(1.0, 1.0, 0.0) ); vec3 col = mix(mix(col4[0], col4[1], pos.x), mix(col4[2], col4[3], pos.x), pos.y); fragColor = vec4(col, 1.0); }

#version 300 es
precision highp float;
out vec4 fragColor;
uniform float u_time;
uniform vec2 u_resolution;

void main(){
  vec2 pos = gl_FragCoord.xy / u_resolution.xy;
  vec3[4] col4 = vec3[](
    vec3(1.0, 0.0, 0.0),
    vec3(0.0, 0.0, 1.0),
    vec3(0.0, 1.0, 0.0),
    vec3(1.0, 1.0, 0.0)
  );
  
  vec3 col = mix(mix(col4[0], col4[1], pos.x), mix(col4[2], col4[3], pos.x), pos.y);
  fragColor = vec4(col, 1.0);
}