#version 410 compatibility

layout(vertices = 4) out;

uniform int tess_level;

in float dist[gl_MaxPatchVertices];

void main()
{
	gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position;
	gl_out[gl_InvocationID].gl_TexCoord[0] = gl_in[gl_InvocationID].gl_TexCoord[0];
	gl_out[gl_InvocationID].gl_TexCoord[1] = gl_in[gl_InvocationID].gl_TexCoord[1];

	const float min_tess_dist = 800.0;
	float t = clamp(1.0 - dist[0] / min_tess_dist, 0.0, 1.0);
	int tess = int(t * float(tess_level - 1.0)) + 1;

	gl_TessLevelInner[0] = tess;
	gl_TessLevelInner[1] = tess;

	gl_TessLevelOuter[0] = tess;
	gl_TessLevelOuter[1] = tess;
	gl_TessLevelOuter[2] = tess;
	gl_TessLevelOuter[3] = tess;
}