How can i have my sphere act as a canvas in viewport

[Linuxuser1234 1]

I would like my sphere to act as a canvas so i can draw lines images etc over a bitmap image of the earth  how can i accomplish this  

[Pat Foley 51]

consider Pi~22/7

 Let the circumference of circle ~  2 * 22/7 

'Convert quarter turn to degree 0.25 round * 44/7   ::  0.25 round    360 degree/1 round = 

 

' Cross out 0.25 round/1 * 360 degree/1 round = 90 degree  

 

'Do same transformation on spin axis. 

 

'Either use law of tangents 13th century spherical triangle work or the newer haversine 1835 to plot x,y I know only a few magic triangles (1,1,sqt(2) = gives 45)   (1, sqt(3), 2 = 30,60) to give you a start.      

 

sqt(2) /2 ~ .707x .707y  Draw out on paper each quadrant to determine signs.      

 

 

 

 

 

 

    

[Linuxuser1234 1]

@Pat Foley What Procedure  would i use to use the equation  

[Pat Foley 51]

On paper.

draw a line Left to right on middle You cut your troubles in half.

draw a line Top to bottom down the center you made a quadrant. 

draw circle holding pencil with smaller fingers put thumbnail at 0.0 and rotate paper with other hand. 

draw in the 45's 30's 60s.  gets you one full sized circle. 

 

Rotate the paper on edge to "transform" it to side view. Notice how original circle flattens to be as thin as a shadow.  You should be able to make your own procedures! Once you get the fundamentals down on paper. 🙂         

   

 

[Linuxuser1234 1]

@Pat Foley

Edited November 6, 2022 by Linuxuser1234

[Pat Foley 51]

Looks like a good start 🙂

 

Here's my stab at it.  I viewed some JavaScript source and looked at the shader code in older Emba' blog article.  What is your target and what video card... That is your business.  Another approach is taking aircraft ground school classes about 5/8 weather plus the instructor can provide a flight to point what various clouds look like. 

 

This has Southern Oscillation Index SOI plus NOI drawn on the bitmap. Remember spherical triangle angles add to more than Euclidean triangle.