% 定义x和y的取值范围
x = linspace(0, 1, 100);
y = linspace(0, 1, 100);

% 创建网格点矩阵
[X, Y] = meshgrid(x, y);

% 根据条件计算函数P的值
Z = zeros(size(X));
Z(Y <= X & X + Y < 1) = 4*X(Y <= X & X + Y < 1) - 4*X(Y <= X & X + Y < 1).^2 + 4*X(Y <= X & X + Y < 1).*Y(Y <= X & X + Y < 1) - 2*Y(Y <= X & X + Y < 1).^2 - 2*Y(Y <= X & X + Y < 1);
Z(Y/2 <= X & X < Y & X + Y < 1) = 4*X(Y/2 <= X & X < Y & X + Y < 1) - 4*X(Y/2 <= X & X < Y & X + Y < 1).*Y(Y/2 <= X & X < Y & X + Y < 1) + 2*Y(Y/2 <= X & X < Y & X + Y < 1).^2 - 2*Y(Y/2 <= X & X < Y & X + Y < 1);
% 绘制三维图形
figure;
surf(X, Y, Z);
xlabel('x');
ylabel('y');
zlabel('P');
title('3D Plot of P');
% 设置颜色映射
colormap('jet');

% 添加颜色条

% 颜色条范围
caxis([-0.3 1]);