GLSL Checkerboard Pattern

Question

i want to shade the quad with checkers:

f(P)=[floor(Px)+floor(Py)]mod2.

My quad is:

glBegin(GL_QUADS);    
  glVerte         


        

Answer 1

May I suggest the following:

float result = mod(dot(vec2(1.0), step(vec2(0.5), fract(v_uv * u_repeat))), 2.0);

• v_uv is a vec2 of UV values,
• u_repeat is a vec2 of how many times the pattern should be repeated for each axis.
• result is 0 or 1, you can use it in mix function to provide colors, for example:

gl_FragColor = mix(vec4(1.0, 1.0, 1.0, 1.0), vec4(0.0, 0.0, 0.0, 1.0) result);