# Colour interference when two surfaces overlap

5 views (last 30 days)
xin on 18 Jun 2024
Commented: xin on 19 Jun 2024
Colour interference when two surfaces overlap, how to solve it？

Piyush Kumar on 18 Jun 2024
Edited: Piyush Kumar on 18 Jun 2024
Hi @xin,
If you are talking about the blending of colours at the point where surfaces intersect or overlap, I will try to explain with an example.
[X,Y] = meshgrid(linspace(-2, 2, 50));
Z = @(x,y,c) x.^2 + y.^2 + c;
figure(1)
surf(X, Y, +Z(X,Y,-4), 'FaceColor','g', 'FaceAlpha',0.5, 'EdgeColor','none')
hold on
surf(X, Y, -Z(X,Y,-4), 'FaceColor','r', 'FaceAlpha',0.5, 'EdgeColor','none')
hold off
grid on
I have specified only 2 colours for the 2 surfaces repectively, but multiple colours are visible. This blending effect is a result of the rendering process in MATLAB, where the semi-transparent (due to 'FaceAlpha',0.5) surfaces allow for the underlying color to show through, creating a visual effect of color mixing or interference.
To avoid this color blending effect and maintain the solid colors you've specified without seeing a mix at the intersections, you can:
• Increase the Opacity: Setting 'FaceAlpha' to 1 (or removing the 'FaceAlpha' setting, as its default value is 1) will make the surfaces fully opaque, preventing the underlying color from showing through.
[X,Y] = meshgrid(linspace(-2, 2, 50));
Z = @(x,y,c) x.^2 + y.^2 + c;
figure(1)
% Making the surfaces opaque by removing 'FaceAlpha'
surf(X, Y, +Z(X,Y,-4), 'FaceColor','g', 'EdgeColor','none')
hold on
surf(X, Y, -Z(X,Y,-4), 'FaceColor','r', 'EdgeColor','none')
hold off
grid on
Piyush Kumar on 18 Jun 2024
Can you share the code you are using?
xin on 19 Jun 2024
Of course,please import the data into the workspace at first.

### Categories

Find more on Lighting, Transparency, and Shading in Help Center and File Exchange

R2018b

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!