Plot area with equation
조회 수: 2 (최근 30일)
이전 댓글 표시
Hello everyone,
I want to plot an area on a sphere, which is defined with the following equations:
R = 50
could somebody help?
Best regards
Alex
댓글 수: 0
채택된 답변
Abdolkarim Mohammadi
2020년 7월 17일
편집: Abdolkarim Mohammadi
2020년 7월 18일
r = 50;
NumPoints = 500;
[UnitX,UnitY,UnitZ] = sphere (NumPoints);
RealX = r * UnitX;
RealY = r * UnitY;
RealZ = r * UnitZ;
x = RealX(:);
y = RealY(:);
z = RealZ(:);
Mask = 2.*y .* (sqrt(r.^2-x.^2-y.^2)./(r.^2)).* sind(15) ...
+ ((r.^2-2*x.^2-2*y.^2)./(r.^2)) .* cosd(15) ...
>= cosd(5.8);
% ----------------
figure ('Position', [62,182,1172,338]);
MaskPatchPositive = all ([Mask,z>0], 2);
MaskPatchNegative = all ([Mask,z<0], 2);
% ----------------
subplot (1,3, 1);
hold on
surf (RealX,RealY,RealZ, ...
'EdgeAlpha', 0.05, ...
'FaceAlpha', 0.05);
scatter3 (x(Mask),y(Mask),z(Mask),9, ...
'MarkerEdgeColor', 'none', ...
'MarkerFaceColor', 'r');
hold off
view ([-35,45]);
grid ('on');
box ('on');
daspect ('auto');
ax = gca;
ax.BoxStyle = 'full';
title ('All points');
% ----------------
subplot (1,3, 2);
hold on
surf (RealX,RealY,RealZ, ...
'EdgeAlpha', 0.1, ...
'FaceAlpha', 0.1);
scatter3 (x(MaskPatchPositive),y(MaskPatchPositive),z(MaskPatchPositive),9, ...
'MarkerEdgeColor', 'none', ...
'MarkerFaceColor', 'r');
hold off
xlim ([-5,5]);
ylim ([0,15]);
zlim ([45,50]);
grid ('on');
box ('on');
daspect ([1,1,1]);
view ([-60,30]);
ax = gca;
ax.BoxStyle = 'full';
title ('Upper part');
% ----------------
subplot (1,3, 3);
hold on
surf (RealX,RealY,RealZ, ...
'EdgeAlpha', 0.1, ...
'FaceAlpha', 0.1);
scatter3 (x(MaskPatchNegative),y(MaskPatchNegative),z(MaskPatchNegative),9, ...
'MarkerEdgeColor', 'none', ...
'MarkerFaceColor', 'r');
hold off
xlim ([-5,5]);
ylim ([0,15]);
zlim ([-50,-45]);
grid ('on');
box ('on');
daspect ([1,1,1]);
view ([-60,30]);
ax = gca;
ax.BoxStyle = 'full';
title ('Lower part');
댓글 수: 3
Abdolkarim Mohammadi
2020년 7월 18일
편집: Abdolkarim Mohammadi
2020년 7월 18일
You are right. I read the post again and realized that I wrote the condition for = cos(5.8) mistakenly, instead of >= cos(5.8). I revised the code and plots and there is no need for Epsilon anymore. You can increase NumPoints to get better accuracy. If the new code is correct, please mark it as the accepted answer. Thanks.
추가 답변 (0개)
참고 항목
카테고리
Help Center 및 File Exchange에서 Delaunay Triangulation에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!