Own reflections

Multiplying a color with a value makes the color brighter or darker.

Adding a color with a value makes the color brighter.

Subtracting a color with a value makes the color darker.

fract(u_time) gives back a values that moves from 0.0 -> 1.0 and starts again at 0.0

To specify to which value it modulates you can use float m = mod(u_time,.5).

Mirror effect

If you move the uv by 0.5 into the center and then use abs() you can create a kaleido/mirror effect.

vec2 uv = gl_FragCoord.xy/u_resolution;
uv -= vec2(0.5);
uv = abs(uv)

Invert colors/values

If you want to invert the colors that you have you can substract your color/value from 1.0 float invertValue = 1.0 - value vec3 invColor = vec3(1.0) - color

If you want to test if a value is smaller than a threshold value you can subtract the value from 1.0

val = step(0.2,0.5) returns 1.0 -> true
1.0 - val = 0 -> false

val2 = step(0.8,0.5) = 0 -> false
1.0 - val = 1 -> true

Coloring

To color you can for example calculate the distance field or the shaper and then just multiply it with a color vec3 or use mix(color1,color2, shape)

Abs Function

Using abs on coordinates creates symmetry around axes when we moved the canvas coord system to the center.

Subtracting

We can create interesting shapes if we take a box as the base and then subtract other boxes from that shape