/*--------------------------------
    Stencil functions
----------------------------------*/

function matcore.StencilStart()
    render.ClearStencil()
    render.SetStencilEnable( true )
    render.SetStencilWriteMask( 1 )
    render.SetStencilTestMask( 1 )
    render.SetStencilFailOperation( STENCILOPERATION_KEEP )
    render.SetStencilZFailOperation( STENCILOPERATION_KEEP )
    render.SetStencilPassOperation( STENCILOPERATION_REPLACE )
    render.SetStencilCompareFunction( STENCILCOMPARISONFUNCTION_ALWAYS )
    render.SetStencilReferenceValue( 1 )
    render.SetColorModulation( 1, 1, 1 )
end

function matcore.StencilStartC(m)
    render.ClearStencil()
    render.SetStencilEnable( true )
    render.SetStencilWriteMask( m )
    render.SetStencilTestMask( 1 )
    render.SetStencilFailOperation( STENCILOPERATION_KEEP )
    render.SetStencilZFailOperation( STENCILOPERATION_KEEP )
    render.SetStencilPassOperation( STENCILOPERATION_REPLACE )
    render.SetStencilCompareFunction( STENCILCOMPARISONFUNCTION_ALWAYS )
    render.SetStencilReferenceValue( 1 )
    render.SetColorModulation( 1, 1, 1 )
end

function matcore.StencilReplace(v)
    render.SetStencilCompareFunction( STENCILCOMPARISONFUNCTION_EQUAL )
    render.SetStencilPassOperation( STENCILOPERATION_REPLACE )
    render.SetStencilReferenceValue(v or 1)
end

function matcore.StencilEnd()
    render.SetStencilEnable( false )
end

/*--------------------------------
    Circles
----------------------------------*/

function matcore.DrawCircle(posx, posy, radius, color)
    local poly = { }
    local v = 40
    for i = 0, v do
        poly[i+1] = {x = math.sin(-math.rad(i/v*360)) * radius + posx, y = math.cos(-math.rad(i/v*360)) * radius + posy}
    end
    draw.NoTexture()
    surface.SetDrawColor(color)
    surface.DrawPoly(poly)
end