#version 430
layout(points) in;
layout(triangle_strip, max_vertices = 48) out;



uniform mat4 View;
uniform mat4 Projection;
uniform vec3 eye_position;
uniform float triangle_step;

layout(location = 0) out vec2 texture_coord;

vec3 vpos = gl_in[0].gl_Position.xyz;
vec3 forward = normalize(eye_position - vpos);
vec3 right = normalize(cross(forward, vec3(0, 1, 0)));
vec3 up = normalize(cross(forward, right));

void EmitPoint(vec2 offset)
{
	vec3 pos = right * offset.x + up * offset.y + vpos;
	gl_Position = Projection * View * vec4(pos, 1.0);
	EmitVertex();
}

void EmitPoint2(vec3 offset)
{
    vec3 pos = vec3(vpos.x + offset.x, vpos.y + offset.y, vpos.z + offset.z);
    gl_Position = Projection * View * vec4(pos, 1);
    EmitVertex();
}

void main()
{
	float ds = triangle_step;

	// Create a quad using triangle strip
	//
	//	3---------2
	//  | \       |
	//  |    \    |
	//  |       \ |
	//  0---------1
	//
	// Triangles: (0, 1, 3), (1, 2, 3)
	float offset_size = 1.0f;

	//FATA SPATE
	texture_coord = vec2(0.0f);
	EmitPoint2(vec3(-ds, -ds, 0));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(ds, -ds, 0));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(-ds, ds, 0));
	EndPrimitive();
	texture_coord = vec2(0.0f);
	EmitPoint2(vec3(-ds, -ds, -0.5f));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(-ds, ds, -0.5f));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(ds, -ds, -0.5f));
	EndPrimitive();


	//3 - 1
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(-ds, ds, 0));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(ds, -ds, 0));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(ds, -ds, -0.5f));
	EndPrimitive();
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(-ds, ds, 0));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(ds, -ds, -0.5f));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(-ds, ds, -0.5f));
	EndPrimitive();

	//3 - 0
	texture_coord = vec2(0, offset_size);
	EmitPoint2(vec3(-ds, ds, 0));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(-ds, ds, -0.5f));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(-ds, -ds, -0.5f));
	EndPrimitive();
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(-ds, -ds, 0));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(-ds, ds, 0.0f));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(-ds, -ds, -0.5f));
	EndPrimitive();

	// 0 - 1
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(ds, -ds, 0));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(-ds, -ds, 0.0f));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(-ds, -ds, -0.5f));
	EndPrimitive();
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(ds, -ds, 0));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(-ds, -ds, -0.5f));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(ds, -ds, -0.5f));
	EndPrimitive();

	// PRIMUL TRIUNGHI

	//FATA SPATE

	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(ds, -ds, 0));
	texture_coord = vec2(offset_size);
	EmitPoint2(vec3(ds, ds, 0));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(-ds, ds, 0));
	EndPrimitive();
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(ds, -ds, -0.5f));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(-ds, ds, -0.5f));
	texture_coord = vec2(offset_size);
	EmitPoint2(vec3(ds, ds, -0.5f));
	EndPrimitive();

	//3 - 1
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(-ds, ds, 0));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(ds, -ds, -0.5f));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(ds, -ds, 0));
	EndPrimitive();
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(-ds, ds, 0));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(-ds, ds, -0.5f));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(ds, -ds, -0.5f));
	EndPrimitive();

	//3 - 2
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(-ds, ds, 0));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(ds, ds, 0.0f));
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(ds, ds, -0.5f));
	EndPrimitive();
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(-ds, ds, 0));
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(ds, ds, -0.5f));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(-ds, ds, -0.5f));
	EndPrimitive();

	//2 - 1
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(ds, ds, -0.5f));
	texture_coord = vec2(0.0f, offset_size);
	EmitPoint2(vec3(ds, ds, 0.0f));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(ds, -ds, 0.0f));
	EndPrimitive();
	texture_coord = vec2(offset_size, offset_size);
	EmitPoint2(vec3(ds, ds, -0.5f));
	texture_coord = vec2(0.0f, 0.0f);
	EmitPoint2(vec3(ds, -ds, 0.0f));
	texture_coord = vec2(offset_size, 0.0f);
	EmitPoint2(vec3(ds, -ds, -0.5f));
	EndPrimitive();

}