8_1_texMapping

Code 8.4, 8.5, Figure 8.4:

8_1_texMapping.frag

#version 300 es precision highp float; precision highp int; out vec4 fragColor; uniform float u_time; uniform vec2 u_resolution; uniform vec2 u_mouse; const float PI = 3.14159265359; //begin rot vec2 rot2(vec2 p, float t){ return vec2(cos(t) * p.x -sin(t) * p.y, sin(t) * p.x + cos(t) * p.y); } vec3 rotX(vec3 p, float t){ return vec3(p.x, rot2(p.yz, t)); } vec3 rotY(vec3 p, float t){ return vec3(p.y, rot2(p.zx, t)).zxy; } vec3 rotZ(vec3 p, float t){ return vec3(rot2(p.xy, t), p.z); } //end rot float text(vec2 st){ return mod(floor(st.s) + floor(st.t), 2.0); } void main(){ vec2 p = (gl_FragCoord.xy * 2.0 - u_resolution) / min(u_resolution.x, u_resolution.y); vec3 cPos = vec3(0.0, 0.0, 0.0); float t = -0.5 * PI * (u_mouse.y / u_resolution.y); vec3 cDir = rotX(vec3(0.0, 0.0, - 1.0), t); vec3 cUp = rotX(vec3(0.0, 1.0, 0.0), t); vec3 cSide = cross(cDir, cUp); float targetDepth = 1.0; vec3 ray = cSide * p.x + cUp * p.y + cDir * targetDepth - cPos; ray = normalize(ray); vec3 groundNormal = vec3(0.0, 1.0, 0.0); float groundHeight = 1.0 + (u_mouse.x / u_resolution.x); if (dot(ray, groundNormal) < 0.0){ vec3 hit = cPos - ray * groundHeight / dot(ray, groundNormal); fragColor.rgb = vec3(text(hit.zx)); } else { fragColor.rgb = vec3(0.0); } fragColor.a = 1.0; }

#version 300 es
precision highp float;
precision highp int;
out vec4 fragColor;
uniform float u_time;
uniform vec2 u_resolution;
uniform vec2 u_mouse;
const float PI = 3.14159265359;

//begin rot
vec2 rot2(vec2 p, float t){
  return vec2(cos(t) * p.x -sin(t) * p.y, sin(t) * p.x + cos(t) * p.y);
}

vec3 rotX(vec3 p, float t){
  return vec3(p.x, rot2(p.yz, t));
}

vec3 rotY(vec3 p, float t){
  return vec3(p.y, rot2(p.zx, t)).zxy;
}

vec3 rotZ(vec3 p, float t){
  return vec3(rot2(p.xy, t), p.z);
}
//end rot

float text(vec2 st){
  return mod(floor(st.s) + floor(st.t), 2.0);
}

void main(){
  vec2 p = (gl_FragCoord.xy * 2.0 - u_resolution) / min(u_resolution.x, u_resolution.y);
  vec3 cPos = vec3(0.0, 0.0, 0.0);
  float t = -0.5 * PI * (u_mouse.y / u_resolution.y);
  vec3 cDir = rotX(vec3(0.0, 0.0, - 1.0), t);
  vec3 cUp = rotX(vec3(0.0, 1.0, 0.0), t);
  vec3 cSide = cross(cDir, cUp);
  float targetDepth = 1.0;
  vec3 ray = cSide * p.x + cUp * p.y + cDir * targetDepth - cPos;
  ray = normalize(ray);
  vec3 groundNormal = vec3(0.0, 1.0, 0.0);
  float groundHeight = 1.0 + (u_mouse.x / u_resolution.x);
  if (dot(ray, groundNormal) < 0.0){
    vec3 hit = cPos - ray * groundHeight / dot(ray, groundNormal);
    fragColor.rgb = vec3(text(hit.zx));
  } else {
    fragColor.rgb = vec3(0.0);
  }
  fragColor.a = 1.0;
}