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Circle 2D Map

Posted: Sat Nov 12, 2011 7:26 am
by arsenavin
Hello, i am newbie here..
Currently i am developing 3D environment + 2D map for my final project (Opengl,C++)
My problem is how to draw the "Circle Shape" Map to the 3D environment screen?
It like a GTA interactive map..
Image
Any idea?

Re: Circle 2D Map

Posted: Sat Nov 12, 2011 10:22 pm
by leileilol
GTA3 does it by a circle texture with an alpha with a GE128 blend and a depthwrite, and many small textures of the map in little pieces (since PS2 cache sucks)
then it reads the depth of that circle texture to trim it to that circle
A second alpha-blended circle is applied on top to soften the transition with a black circle border.

Re: Circle 2D Map

Posted: Sun Nov 13, 2011 3:11 am
by arsenavin
leileilol wrote:GTA3 does it by a circle texture with an alpha with a GE128 blend and a depthwrite, and many small textures of the map in little pieces (since PS2 cache sucks)
then it reads the depth of that circle texture to trim it to that circle
A second alpha-blended circle is applied on top to soften the transition with a black circle border.

I am need a deeper explanation here..thanx by the way.