Crafter.Graphics/MeshShaderMixedVoxelGrid.glsl

/*
 * 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 sizeX;
    uint sizeY;
    uint sizeZ;
} ubo;

struct VoxelType
{
    uint type;
};

layout (binding = 1) buffer VOXELS
{
	VoxelType voxel[];
} voxels;

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

shared uint writeCounter;

layout(local_size_x = 16, local_size_y = 1, local_size_z = 1) in;
layout(triangles, max_vertices = 128, max_primitives = 192) out;
void main()
{
    if (gl_LocalInvocationIndex == 0) {
        writeCounter = 0;
    }

    barrier();

    uint type = voxels.voxel[gl_GlobalInvocationID.x].type;

    if(type != 0) {
        uint old = atomicAdd(writeCounter, 1);
        uint z = gl_GlobalInvocationID.x / (ubo.sizeX * ubo.sizeY);
        uint y = (gl_GlobalInvocationID.x % (ubo.sizeX * ubo.sizeY)) / ubo.sizeX;
        uint x = gl_GlobalInvocationID.x % ubo.sizeX;

        float zF = float(z);
        float yF = float(y);
        float xF = float(x);

        uint oldVertexOffset = old*8;

        gl_MeshVerticesEXT[oldVertexOffset + 0].gl_Position = ubo.modelProjectionView * vec4(xF - 0.5, yF - 0.5, zF - 0.5, 1.0);
        gl_MeshVerticesEXT[oldVertexOffset + 1].gl_Position = ubo.modelProjectionView * vec4(xF + 0.5, yF - 0.5, zF - 0.5, 1.0);
        gl_MeshVerticesEXT[oldVertexOffset + 2].gl_Position = ubo.modelProjectionView * vec4(xF + 0.5, yF + 0.5, zF - 0.5, 1.0);
        gl_MeshVerticesEXT[oldVertexOffset + 3].gl_Position = ubo.modelProjectionView * vec4(xF - 0.5, yF + 0.5, zF - 0.5, 1.0);
        gl_MeshVerticesEXT[oldVertexOffset + 4].gl_Position = ubo.modelProjectionView * vec4(xF - 0.5, yF - 0.5, zF + 0.5, 1.0);
        gl_MeshVerticesEXT[oldVertexOffset + 5].gl_Position = ubo.modelProjectionView * vec4(xF + 0.5, yF - 0.5, zF + 0.5, 1.0);
        gl_MeshVerticesEXT[oldVertexOffset + 6].gl_Position = ubo.modelProjectionView * vec4(xF + 0.5, yF + 0.5, zF + 0.5, 1.0);
        gl_MeshVerticesEXT[oldVertexOffset + 7].gl_Position = ubo.modelProjectionView * vec4(xF - 0.5, yF + 0.5, zF + 0.5, 1.0);

        uint oldPrimOffset = old*12;

        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 0] = uvec3(oldVertexOffset + 2, oldVertexOffset + 1, oldVertexOffset + 0);
        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 1] = uvec3(oldVertexOffset + 0, oldVertexOffset + 3, oldVertexOffset + 2);

        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 2] = uvec3(oldVertexOffset + 4, oldVertexOffset + 5, oldVertexOffset + 6);
        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 3] = uvec3(oldVertexOffset + 4, oldVertexOffset + 6, oldVertexOffset + 7);

        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 4] = uvec3(oldVertexOffset + 0, oldVertexOffset + 1, oldVertexOffset + 5);
        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 5] = uvec3(oldVertexOffset + 5, oldVertexOffset + 4, oldVertexOffset + 0);

        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 6] = uvec3(oldVertexOffset + 3, oldVertexOffset + 6, oldVertexOffset + 2);
        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 7] = uvec3(oldVertexOffset + 3, oldVertexOffset + 7, oldVertexOffset + 6);

        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 8] = uvec3(oldVertexOffset + 7, oldVertexOffset + 3, oldVertexOffset + 0);
        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 9] = uvec3(oldVertexOffset + 4, oldVertexOffset + 7, oldVertexOffset + 0);

        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 10] = uvec3(oldVertexOffset + 1, oldVertexOffset + 2, oldVertexOffset + 6);
        gl_PrimitiveTriangleIndicesEXT[oldPrimOffset + 11] = uvec3(oldVertexOffset + 6, oldVertexOffset + 5, oldVertexOffset + 1);
    }

    barrier();

    SetMeshOutputsEXT(writeCounter*8, writeCounter*12);

    SetMeshOutputsEXT(128, 192);
}


/**

 int z = gl_GlobalInvocationID.x / (ubo.sizeX * ubo.sizeY);
        int y = (gl_GlobalInvocationID.x % (ubo.sizeX * ubo.sizeY)) / ubo.sizeX;
        int x = gl_GlobalInvocationID.x % ubo.sizeX;

        // Top (y+1) if within bounds
        if (y < ubo.sizeY - 1 && vertex.pos[gl_GlobalInvocationID.x + ubo.sizeX]) {

        }

        // Bottom (y-1) if within bounds
        if (y > 0 && vertex.pos[gl_GlobalInvocationID.x - ubo.sizeX]) {

        }

        // Left (x-1) if within bounds
        if (x > 0 && vertex.pos[gl_GlobalInvocationID.x - 1]) {

        }

        // Right (x+1) if within bounds
        if (x < ubo.sizeX - 1 && vertex.pos[gl_GlobalInvocationID.x + 1]) {

        }

        // Front (z+1) if within bounds
        if (z < ubo.sizeZ - 1 && vertex.pos[gl_GlobalInvocationID.x + ubo.sizeX * ubo.sizeY]) {

        }

        // Back (z-1) if within bounds
        if (z > 0 && vertex.pos[gl_GlobalInvocationID.x - ubo.sizeX * ubo.sizeY]) {

        }
        **/