Scratch

Oh, you finally figured out a method 
I'm sorry to say, however, that if you tilt the cube at a standard isometric perspective (more or less) the draw order still messes up. (like so)

Also, it's flashy, and it appears to clear before it finishes drawing.

... I thought of an idea for a 3D engine. It would be deathly slow, but I think it might work. For each pixel, pretend it is like a ray coming from your eye. find where it hits a surface, and make the pixel on the screen that color. You could add extra variables to the surfaces, like shiny-ness, so you could bounce your ray off the surface you just touched onto another surface, where you would take that color and do some math with it to combine it with your other surface's color and so on. The problem is that I'm having trouble thinking of a way to see where a ray intersects a surface, or if it does at all. Could you help?

So THAT'S what ray-tracing is. Thanks, there are so many different ways to make 3D. I learned something new!    But I would still like an answer to my question 

zubblewu wrote:

applejack wrote:

... I thought of an idea for a 3D engine. It would be deathly slow, but I think it might work. For each pixel, pretend it is like a ray coming from your eye. find where it hits a surface, and make the pixel on the screen that color. You could add extra variables to the surfaces, like shiny-ness, so you could bounce your ray off the surface you just touched onto another surface, where you would take that color and do some math with it to combine it with your other surface's color and so on. The problem is that I'm having trouble thinking of a way to see where a ray intersects a surface, or if it does at all. Could you help?

That's called ray tracing 

applejack wrote:

So THAT'S what ray-tracing is. Thanks, there are so many different ways to make 3D. I learned something new!    But I would still like an answer to my question 

zubblewu wrote:

applejack wrote:

... I thought of an idea for a 3D engine. It would be deathly slow, but I think it might work. For each pixel, pretend it is like a ray coming from your eye. find where it hits a surface, and make the pixel on the screen that color. You could add extra variables to the surfaces, like shiny-ness, so you could bounce your ray off the surface you just touched onto another surface, where you would take that color and do some math with it to combine it with your other surface's color and so on. The problem is that I'm having trouble thinking of a way to see where a ray intersects a surface, or if it does at all. Could you help?

That's called ray tracing 

You can check out this project by me for a simple raytracer. 

LS97 wrote:

And, for the culling:

I honestly doubt you'll ever need any when rendering a cube. For other purposes, the methods will be way too slow (I think even the quickest way would have to loop through all the other polygons to determine whether they cover the one you want)... assuming you're talking about occlusion culling.

I am talking about occlusion culling. Right now, I'm using a not-so-accurate method where I test the average Z positions. I am actively working on a better version though.

And yes, you do have to check each polygon against the other, making efficient occlusion tests is a hard CS problem which people are working on even today.

Last edited by Hardmath123 (2012-05-21 01:41:55)

Cool but when I turned the thing around, one part was rendered in front of the part that was meant to be at the front.

I like it, but why do you call this OpenGL? 

Very good. I can't wait to see the new versions with bug fixes. :3

Almost too good to be just in Scratch!    And 1 sprite 1 script, too!
And even though this is a slightly technical project, it does belong in Show and Tell. You could just mention "1S1S 3D graphics" in the title to attract people who don't know what OpenGL is. 

scimonster wrote:

Almost too good to be just in Scratch!    And 1 sprite 1 script, too!
And even though this is a slightly technical project, it does belong in Show and Tell. You could just mention "1S1S 3D graphics" in the title to attract people who don't know what OpenGL is. 

I'm not so sure it goes in show and tell.  In the past, projects like this were put in Advanced Topics, because of the advanced code.  Y'know, because of the advanced-ness.

Last edited by gbear605 (2012-05-21 18:03:48)

Hardmath123 wrote:

scimonster wrote:

Almost too good to be just in Scratch!    And 1 sprite 1 script, too!
And even though this is a slightly technical project, it does belong in Show and Tell. You could just mention "1S1S 3D graphics" in the title to attract people who don't know what OpenGL is. 

I put this in the ATs deliberately, because this project uses hard math and tries to simulate a complex programming library. It's the kind of thing we Advanced Scratchers love, so I wanted to see how they would react, what questions they would have.

Another, bigger, reason was the fact that I was asking for the answer to a complex math problem (depth testing), and I was pretty sure I was only gonna get a response from our geniuses over at the ATs, not from people at the Show and Tell (no offense to the Show & Tell guys, it's just that I don't see much complex math around there).

So please move it back to the ATs. Thanks! 

I'll buy those arguments 

Could some of the stuff on this blog help you?

(with the z-indexing)

Last edited by rookwood101 (2012-05-22 13:43:32)