I already asked this question but I didn't get my answer. Btw I found some thing new.I want to show a 3D model from a wrl file exported by solid works.The file contains triangle's vertices and I am drawing them with glBegin(GL_TRIANGLES), But it doesn't looks nice and doesn't seems quite 3D! I tried gluSphere to draw an sphere in that scene with same lighting setting and it seems very nice and 3D!!!!
Is there some thing about Glu ?
Should I use Glu for draw triangles?
To get a good shading you should also supply normals for the triangles.
Related
I have model of skull loaded from .obj file based on this tutorial . As long as I understand texture mapping of cube (make triangle on texture in range of [0,1], select one of six side, select triangle of two triangles on this side and map it with your triangle from texture), I have problem with thinking for any solution to texture mapping my skull. There are few thousands of triangles on it and I think that texture mapping them manually is more than wrong.
Is there any solution for this problem? I'll appreciate any piece of code since it may tell me more than just description of solution.
You can generate your UV coordinates automatically, but this will probably produce badly looking ouput except for very simple textures.
For detailed textures that have eyes, ears, etc., you need to crate your UV coordinates by hand in some 3d modeling tool like is Blender 3d, 3DS Max etc... There is a lot of tutorials all over the internet how to do that. (https://www.youtube.com/watch?v=eCGGe4jLo3M)
I want to represent my Objects as textured convex Polygons. For the most part those will just be rotated rectangles but i want to support convex shapes too and thats where the problems arise.
I worked with Blender a while ago and there you could unwrap the 3D-Objects and explicetely tell Blender which vertex of the Shape has which Position on the Texture.
Would it maybe be better to just request the Texture to have the size of the bounding Rectangle of the Shape so I can just apply the texture with SFML?
PS: Im sorry i cant post pictures to clarify my question.
or OpenGL
In OpenGL, typically you'll have two (or more!) vertex attributes: position and texture coordinate. That's basically saying which vertex of the Shape has which Position on the Texture.
That's what SFML has to be doing internally, and since its Open-Source, you might just peek inside and see if your "bounding rectangle" idea has a chance of working (my guess is that it indeed does).
I have been asked to do 3D sphere and adding textures to it so that it looks like different planets in the Solar System. However 3ds max was not mentioned as mandatory.
So, how can I make 3D spheres using OpenGL and add textures to it? using glutsphere or am I suppose to do it some other method and how to textures ?
The obvious route would be gluSphere (note, it's glu, not glut) with gluQuadricTexture to get the texturing done.
I am not sure if glutSolidSphere has texture coordinates (as far as I can remeber they were not correct, or not existant). I remember that this was a great resource to get me started on the subject though:
http://paulbourke.net/texture_colour/texturemap/
EDIT:
I just remembered that subdividing an icosahedron gives a better sphere. Also texture coordinates are easier to implement that way:
see here:
http://www.gamedev.net/topic/116312-request-for-help-texture-mapping-a-subdivided-icosahedron/
and
http://www.sulaco.co.za/drawing_icosahedron_tutorial.htm
and
http://student.ulb.ac.be/~claugero/sphere/
I would like to draw a simple 2D stickman on the screen. I also want it to be anti-aliased.
The problem is that I want to use a bones system, which will be written after I would know how to draw the stickman itself based on the joints positions. This means I can't use sprites - I want my stickman to be fully controlable in the code.
It would be great if it will be possible to draw curves too.
Drawing a 3D stickman using a model would also be great if not better. The camera will be positioned like it's 2D, but I would still have depth. The problem is that I only have experience in Maya, and exporting and vertex weighting of the model in OpenGL seems like a mess...
I tried to find libraries for 2D anti-aliased drawing or enable multi-sampling and draw normally, but I had no luck. I also tried to use OpenGL's native anti-aliasing but it seems deprecated and the line joins are bad...
I don't want it to be too complicated because, well, it shouldn't be - it's just the first part of my program, and it's drawing a stickman...
I hope you guys can help me, I'm sure you know better than me :)
You could enable GL_SMOOTH. To check if you device supports your required line width for smooth lines, you can use glGet(GL_SMOOTH_LINE_WIDTH_RANGE);
If you want your code to be generic, you can also use antialiased textures.
Take a look at this link
http://www.opengl.org/resources/code/samples/advanced/advanced97/notes/node62.html
The only way to get antialiasing is use GL library which knows how to get antialiased GL context, for example, SDL. As of stickman, you can draw him with colored polygons.
I want to draw many spheres (~100k) using OpenGL. So far, I'm doing something like
for (int i=0; i<pnum; i++){
glPushMatrix();
glTranslatef(bpos[i].x, bpos[i].y, bpos[i].z);
glCallList(DListSPHERE);
glPopMatrix();
}
Before using proper spheres, I used GL_POINTS. That allowed me to call glDrawArrays with an array containing all points which was very efficient. Is there a better way than the above code to draw many, identical objects?
Have a look at this page on instancing: it contains many references:
Some test made that shows when to use instancing and when not: http://www.ozone3d.net/blogs/lab/?p=87
An OpenGL implementation of a pseduo-instancing (recommended for old hardware).
glsl_pseudo_instancing.pdf
OpenGL instancing:
http://www.opengl.org/registry/specs/EXT/draw_instanced.txt
See also Geometry instancing on Wikipedia.
If you draw ~100k spheres, you might want to consider raycasting them instead of using polygon meshes to approximate them. The papers GPU-Based Ray-Casting of Quadratic Surfaces by Sigg et al. (2006) and Splatting Illuminated Ellipsoids with Depth Correction by Gumhold (2003) show how to do this. If you do this, you can reuse much of your fast point sprite code.
You could use point sprites and a fragment shader to duplicate the effect of a rendered sphere without the actual sphere geometry. I would try instancing first, however.