/*
Crafter®.Graphics
Copyright (C) 2025 Catcrafts®
Catcrafts.net

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3.0 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
*/

#version 450
#extension GL_EXT_mesh_shader : require

layout (binding = 0) uniform UBO 
{
	mat4 modelProjectionView;
	uint stride;
	float spacing;
	uint padding[14];
} ubo;

struct VertexType
{
    float height;
	float padding[3];
    vec4 color;
};

layout (binding = 1) buffer VERTEX 
{
	VertexType pos[];
} vertex;


layout(local_size_x = 64, local_size_y = 1, local_size_z = 1) in;
layout(triangles, max_vertices = 256, max_primitives = 128) out;

layout (location = 0) out PerVertexData
{
  vec4 color;
} outVert[]; 

void main()
{
	SetMeshOutputsEXT(256, 128);

	uint linearID = gl_GlobalInvocationID.x;
    uint quadX = linearID % ubo.stride;
    uint quadZ = linearID / ubo.stride;

	VertexType vertex1 = vertex.pos[quadZ * ubo.stride + quadX];
	VertexType vertex2 = vertex.pos[quadZ * ubo.stride + quadX + 1];
	VertexType vertex3 = vertex.pos[(quadZ+1) * ubo.stride + quadX];
	VertexType vertex4 = vertex.pos[(quadZ+1) * ubo.stride + quadX + 1];

	uint vertexID = gl_LocalInvocationID.x*4;

	gl_MeshVerticesEXT[vertexID].gl_Position = 	   ubo.modelProjectionView * vec4(ubo.spacing*quadX, 				0, 	ubo.spacing*quadZ, 1); // Top-left
	gl_MeshVerticesEXT[vertexID + 1].gl_Position = ubo.modelProjectionView * vec4(ubo.spacing*quadX+ubo.spacing, 	0, 	ubo.spacing*quadZ, 1); // Top-right
	gl_MeshVerticesEXT[vertexID + 2].gl_Position = ubo.modelProjectionView * vec4(ubo.spacing*quadX, 				0,	ubo.spacing*quadZ+ubo.spacing, 1); // Bottom-left
	gl_MeshVerticesEXT[vertexID + 3].gl_Position = ubo.modelProjectionView * vec4(ubo.spacing*quadX+ubo.spacing,	0, 	ubo.spacing*quadZ+ubo.spacing, 1); // Bottom-right

	outVert[vertexID].color = vertex1.color;
	outVert[vertexID + 1].color = vertex2.color;
	outVert[vertexID+ 2].color = vertex3.color;
	outVert[vertexID + 3].color = vertex4.color;

	uint triangleID = gl_LocalInvocationID.x*2;

	gl_PrimitiveTriangleIndicesEXT[triangleID] = uvec3(vertexID+2, vertexID+1, vertexID);
	gl_PrimitiveTriangleIndicesEXT[triangleID + 1] = uvec3(vertexID+3, vertexID+1, vertexID+2);
}