OpenGL Odd black circle on glutSolidSpheres

Recommended Posts

Hello, haven't been able to find anything via the search: I've got a simple opengl windows app which draws a couple of spheres (drawn using glutSolidSphere routine). When I do the following : glMatrixMode (GL_PROJECTION); glLoadIdentity (); glFrustum (-2.0, 2.0, -2.0, 2.0, 1.5, 50.0); and recompile/run the program everything works fine EXCEPT there are two odd black circles on my spheres. <can't seem to post a pic, will add a link if I can't figure this out> Basically I'm wondering if there's an obvious reason that switching to projection mode/using my specified frustum would cause those circles to appear. When I move the sphere(s) to the far left side they turn from black to white, and it seems to be controlled by the lighting (one light in the scene). When they go to the right side it stays black. Any help appreciated, if its not obvious don't feel bad about just moving on :)

Share on other sites
http://img180.imageshack.us/img180/8681/sphereswithblemishoz1.jpg

Here's the image, the circles move with the spheres.

Share on other sites
Hmm... if you change your background colour, does this colour appear in the "spots", or do they remain black? If they do change with the background colour, then perhaps (although this seems odd to me, given their placement) the spheres are too close to your near plane, or, conversely, your near plane is too far out.

Share on other sites
Oddly it remains black if I change the background color to, say, green.

Create an account

Register a new account

• Partner Spotlight

• Forum Statistics

• Total Topics
627684
• Total Posts
2978627
• Similar Content

• Both functions are available since 3.0, and I'm currently using glMapBuffer(), which works fine.
But, I was wondering if anyone has experienced advantage in using glMapBufferRange(), which allows to specify the range of the mapped buffer. Could this be only a safety measure or does it improve performance?
Note: I'm not asking about glBufferSubData()/glBufferData. Those two are irrelevant in this case.
• By xhcao
Before using void glBindImageTexture(    GLuint unit, GLuint texture, GLint level, GLboolean layered, GLint layer, GLenum access, GLenum format), does need to make sure that texture is completeness.
• By cebugdev
hi guys,
are there any books, link online or any other resources that discusses on how to build special effects such as magic, lightning, etc. in OpenGL? i mean, yeah most of them are using particles but im looking for resources specifically on how to manipulate the particles to look like an effect that can be use for games,. i did fire particle before, and I want to learn how to do the other 'magic' as well.
Like are there one book or link(cant find in google) that atleast featured how to make different particle effects in OpenGL (or DirectX)? If there is no one stop shop for it, maybe ill just look for some tips on how to make a particle engine that is flexible enough to enable me to design different effects/magic
let me know if you guys have recommendations.
• By dud3
How do we rotate the camera around x axis 360 degrees, without having the strange effect as in my video below?
Mine behaves exactly the same way spherical coordinates would, I'm using euler angles.
Tried googling, but couldn't find a proper answer, guessing I don't know what exactly to google for, googled 'rotate 360 around x axis', got no proper answers.

References:
Code: https://pastebin.com/Hcshj3FQ
The video shows the difference between blender and my rotation:

• By Defend
I've had a Google around for this but haven't yet found some solid advice. There is a lot of "it depends", but I'm not sure on what.
My question is what's a good rule of thumb to follow when it comes to creating/using VBOs & VAOs? As in, when should I use multiple or when should I not? My understanding so far is that if I need a new VBO, then I need a new VAO. So when it comes to rendering multiple objects I can either:
* make lots of VAO/VBO pairs and flip through them to render different objects, or
* make one big VBO and jump around its memory to render different objects.
I also understand that if I need to render objects with different vertex attributes, then a new VAO is necessary in this case.
If that "it depends" really is quite variable, what's best for a beginner with OpenGL, assuming that better approaches can be learnt later with better understanding?

• 9
• 14
• 12
• 10
• 12