CODEWITHSUNDEEP
opengl-escurve
Evgeny Shurakov
Evgeny Shurakov

Reputation: 6082

Drawing semi-transparent curves in OpenGL ES

My goal is to draw a semi-transparent curve. User moves cursor and I draw the curve under the cursor.

I've tried to use antialiased points to draw line, but I don't know how to make it transparent. I can't use lines to draw the curve, because can't set both antialiasing and line width.

Should I use triangle strip to draw curve?

Upvotes: 0

Views: 2061

Answers (1)

prideout
prideout

Reputation: 3019

Yeah, if you want to do a nice job with this, you could tessellate your wide curve into a triangle strip. There are many papers written about stroke tessellation.

You can then texture your triangle strip with a square alpha texture that has a nice solid, anti-aliased circle in it -- this causes the wide line to appear anti-aliased! Check it out:

http://homepage.mac.com/arekkusu/bugs/invariance/TexAA.html

Very cool stuff.

Upvotes: 2

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