寻求满足特定功能的免费几何绘图工具

Hey there! After going through your detailed requirements, I’ve got two reliable free tools that check every single box you listed:

GeoGebra #

This is a total workhorse for geometry tasks, and it nails all your needs:

• Customizable shape gallery: You’ll find circles, squares, triangles, and more—drag to resize, pick any color for outlines or fills instantly.
• Fill enclosed areas: Want to color the overlap of two circles red? Just construct the intersection area (it’s super intuitive) and apply the fill color. You can also fill any closed region you draw, like that curved-side triangle you mentioned (build the shape, select the enclosed space, and color it).
• Connect feature points: It automatically detects key points—midpoints of sides, corners, circle centers, quadrant points on circumferences, you name it. Just click two points and draw a line between them; drawing diameters or connecting midpoints takes seconds.
• Text insertion: Add labels, notes, or any text you need, and tweak the font, size, and position to fit your diagram perfectly.
• Best of all, it’s 100% free to use, with both web and desktop versions available.

Desmos Geometry #

Another fantastic free option that’s super user-friendly:

• Shape customization: Drag shapes to adjust size, rotate them, and choose any color for fills or outlines. The shape library covers all basic geometry shapes plus some more complex ones.
• Fill closed regions: Construct your desired shape (like the square with upper quadrants removed to make that curved triangle) and the tool lets you fill any enclosed area with a click. Overlapping circle fills? No problem at all.
• Feature point connections: It highlights all the key points on your shapes as you work—click any two (say, a circle’s center and a quadrant point) to draw a line instantly. No fumbling to find the right spots.
• Text support: Insert text labels anywhere in your diagram, format them to match your design, and move them around easily.

Both of these tools fix the gaps you noticed in Draw.io (no enclosed area filling) and Paint/Sketchpad (no feature point snapping). Give them a try—they should handle everything you need to create those geometry diagrams smoothly!

备注：内容来源于stack exchange，提问作者user110391