test.tesc

#version 430

// number of CPs in patch
layout (vertices = 3) out;

uniform vec3 viewPos;
uniform sampler2D heightsTexture;

// from VS (use empty modifier [] so we can say anything)
in vec3 vPosition[];
in vec2 vTexCoord[];

in VS_OUT {
  vec3 FragPos;
  vec2 TexCoords;
  vec3 TangentLightPos;
  vec3 TangentViewPos;
  vec3 TangentFragPos;
} tc_in[];

// to evluation shader. will be used to guide positioning of generated points
out vec3 evaluationpoint_wor[];
out vec2 tcTexCoord[];

bool newMet = false;

out TC_OUT
{
  vec3 FragPos;
  vec2 TexCoords;
  vec3 TangentLightPos;
  vec3 TangentViewPos;
  vec3 TangentFragPos;
} tc_out[];

const float levelOfDetail = 512;
const float maxLodDistance = 8;
const float k = levelOfDetail * maxLodDistance;

float LOD(vec3 posV, vec3 cam){
  float dist = distance(posV, cam);

  int n = int(log2(clamp(k / dist, 1, levelOfDetail)));
	return float(1<<n);
}
 
void main () {
  tc_out[gl_InvocationID].FragPos         = tc_in[gl_InvocationID].FragPos;
	tc_out[gl_InvocationID].TexCoords       = tc_in[gl_InvocationID].TexCoords;
	tc_out[gl_InvocationID].TangentLightPos = tc_in[gl_InvocationID].TangentLightPos;
	tc_out[gl_InvocationID].TangentViewPos  = tc_in[gl_InvocationID].TangentViewPos;
  tc_out[gl_InvocationID].TangentFragPos  = tc_in[gl_InvocationID].TangentFragPos;

  tcTexCoord[gl_InvocationID]  = vTexCoord[gl_InvocationID];

  evaluationpoint_wor[gl_InvocationID] = vPosition[gl_InvocationID];

  float TessLevelInner = 1;
  float e0, e1, e2;
  vec3 d0, d1, d2;

  e0 = e1 = e2 = 1;

  if (gl_InvocationID == 0) {
    vec3 v0 = gl_in[0].gl_Position.xyz;
    vec3 v1 = gl_in[1].gl_Position.xyz;
    vec3 v2 = gl_in[2].gl_Position.xyz;

    vec3 bTriangle = (gl_in[0].gl_Position.xyz + gl_in[1].gl_Position.xyz + gl_in[2].gl_Position.xyz)/3;
    TessLevelInner = LOD(bTriangle, viewPos);

    d0 = v1+(v2-v1)/2;
    d1 = v0+(v2-v0)/2;
    d2 = v0+(v1-v0)/2;

    e0 = LOD(d0,viewPos);
    e1 = LOD(d1,viewPos);
    e2 = LOD(d2,viewPos);
  }
 
  gl_TessLevelInner[0] = TessLevelInner; // number of nested primitives to generate
  gl_TessLevelOuter[0] = e0; // times to subdivide first side
  gl_TessLevelOuter[1] = e1; // times to subdivide second side
  gl_TessLevelOuter[2] = e2; // times to subdivide third side
}