Plotting a 3D graph in Latex

Question

I am trying to change the 2D scatter graph into 3D which can also take the value of the P column as z-axis. But the output I got is not smooth and I really don't understand how I can change it into 3D graph which shows the regions where cost DR, BR or SC is optimal for (P:Q:R) coordinates. Can any expert please help me draw a nice 3D graph of the given data? In the code, I am using a minimum dataset for illustration purpose although the actual file is so big with many data points. Here is the code:

\documentclass[border=5mm]{standalone}
\usepackage{pgfplotstable}
\pgfplotsset{compat=1.16}
\pgfplotstableread[col sep=comma]{
P, Q, R, cost
6, 3, 1, SC
6, 2, 2, SC
6, 1, 3, SC
5, 4, 1, DR
5, 3, 2, BR
5, 2, 3, DR
5, 1, 4, DR
4, 5, 1, DR
4, 4, 2, BR
4, 3, 3, BR
}\MyData
\begin{document}
    \begin{tikzpicture}
    % define a few macros for convenience
    \newcommand\AxisW{10cm} % width/height of axis
    \newcommand\AxisXMin{0.5} % xmin/ymin
    \newcommand\AxisRange{10} % range of axis, x y and z
    \begin{axis}[
    % define how the different cases are drawn
    % all should have same mark and draw opacity,
    % but change the color as you prefer
    scatter/classes={
        SC={mark=square, draw opacity=0, fill=blue},
        DR={mark=square, draw opacity=0, fill=red},
        BR={mark=square*, draw opacity=0, fill=green}
    },
% add labels for the axes
xlabel=R,
ylabel=Q,
zlabel=P,
% set up the size of the axis
scale only axis, % width/height applies to axis box alone, without labels
width=\AxisW, height=\AxisW,
% set up the range of the axes
xmin=\AxisXMin, xmax=\AxisXMin+\AxisRange,
ymin=\AxisXMin, ymax=\AxisXMin+\AxisRange,
zmin=\AxisXMin, zmax=\AxisXMin+\AxisRange,
% calculate the mark size - divide by 2 because the size is half the width
mark size={\AxisW/\AxisRange/2},
% set legend entries in one row
legend columns=-1,
% move legend outside top of axis
legend style={at={(0.5,1.02)}, anchor=south},
% have ticks every 1 unit distance
xtick distance=1,ytick distance=1,ztick distance=1,
]
\addplot3 [
scatter, % make a scatter plot
only marks, 
scatter src=explicit symbolic 
]
table[x=R, % use R-column for x-values
y=Q, use Q-column for y-values
z=P, % use P-column for z-values
meta=cost % use cost-column to define which scatter class should be used
] \MyData;
\legend{SC, DR, BR}
\end{axis}
\end{tikzpicture}
\end{document}