So I've got this class where I have to make a simple game in OpenGL.
I want to make space invanders (basically).
So how in the world should I make anything appear on my screen that looks decent at all? :(
I found some code, finally, that let me import a 3DS object. It was sweet I thought and went and put it in a class to make it a little more modular and usable (http://www.spacesimulator.net/tut4_3dsloader.html).
However, either the program I use (Cheetah3d) is exporting the uv map incorrectly and/or the code for reading in a .bmp that ISN'T the one that came with the demo. The image is all weird. Very hard to explain.
So I arrive at my question. What solution should I use to draw objects? Should I honestly expect to spend hours guessing at vertices to make a space invader ship? Then also try to map a decent texture to this object as well? The code I am using draws the untextured object just fine but I can't begin to go mapping the texture to it because I don't know what vertices correspond to what polygons etc.
Thanks SO for any suggestions on what I should do. :D
You could draw textured quads, provided you have a texture loader.
I really wouldn't worry too much about your "uv map" - if you can get your vertices right then you can generally cludge something anyway. That's what I'd do.
Related
I am going to split this question in 3 parts
First, I've been given this problem, and I don't know where to start, if you have been solving related problem, would you give me some hints and keywords to help me do some more research?
I have done some research on my own
So here is some 2D chest CT scans (sorry due to reputation rule i can't implement images directly)
All photos are in the same angle. So I think I can simply read each photo to a vector of pixels, do some thresh holding to make all black and black-ish pixels going to be a non-colored pixel. Next, I'll create a vector called vector_of_photo of those vectors. Then the index of each vector in vector_of_photo are now the Z-index.
Now I can render a 3d photo from those vectors of pixels right?
In the second place, I got trouble understand raycasting algorithm,
I think the idea here is, when I already got a box of pixel then everytime I rotate the box, it cast straight-lines from that angle of the camera to the box, each line found a has-colored pixel going to stop casting and render that pixel (or more specific, copy the pixel to the exactly location on the plane).
Did I understand it correctly?
At last, the OPENGL/c++ part is just the option I think I'm going to use to solve this problem. And I'm not pretty sure it is a good idea or not, so give me some more hint about the programming language, library or module I should take a look at.
I happen to be working on the same problem in my spare time. Haha :)
Here is one approach to your problem:
Load the images into your application, such that you get the 3D volumetric dataset that you describe
Remove all points that don't fit within some range of values (e.g. 0.4/1.0 to 0.6/1.0 brightness). You may need to apply preprocessing and filtering.
Fit a mesh to the resulting point cloud with open-source software. Here is a good blog post about that
https://towardsdatascience.com/5-step-guide-to-generate-3d-meshes-from-point-clouds-with-python-36bad397d8ba
Take the resulting mesh (probably, an STL file) and visualize it in any software your want (Blender 3D, Unity 3D, Cinema 4D, a custom OpenGL application), anything really.
My own approach to this problem is very similar to the one you suggest in your question, and I have already made some headway. Therefore, I thought it would be good to suggest another route.
NOTE Please be aware that what you are working on is not a trivial problem. It's a large project, and there are many Commerical companies that put years into doing just this. This is a great project for learning OpenGL, rendering, and other concepts. It's perfectly doable, but you may be looking at several months of work, and lots of trial and error. Good luck!
Its not often that two people would happen to work on the same problem, so if you want to discuss further, feel free to contact me over linkedin and/or post a comment below. www.linkedin.com/in/michael-sohnen-a2454b1b2
So I have a project with a lot of data points that are tracked through time, around 10k. What I really want to do is draw a line through each data track. However, everything I have tried seems to really tank performance. I'm really not sure where to start with something this big. My first guess would be spline meshes but, I don't think it would be performant enough.
I've also dabbled a little bit with procedural meshes but, haven't been able to get too far with that either.
My next guess would be something in Niagara as that is how I am drawing the dots currently but, since ribbons can't be drawn on the GPU they aren't good option either. Maybe there is something like a line sprite that I can utilize? I'm not really sure.
I believe there is a way to maybe draw lines similar to that of debug lines which I think might work but, I don't really have a clue where to start on that one.
If anyone has any ideas or can point me in the right direction or have already done something similar I would really appreciate any help!
I want to make a small 2D game in C++. I need to know how to actually render the game. I understand the basics behind opengl, you load vertices into an vbo, load the textures into a vbo and then you can use a draw call using a shader to interpret it. But how do I actually do it in 2D. Do I really only need a vbo storing a single square, and then all the textures, with which I use gltransform to change based on the details of the sprite I am rendering? How do I actually reference the texture I need for the sprite if it is all in one big vbo?
Do you really want to implement this yourself? There are a lot of free libraries out there that do this for you, and are quite good at it (e.g. SFML, SDL, cocos2d-x etc.).
If you're worried about performance issues or something along those lines, then stop, because you're most likely wrong.
If, however, you want to learn how it's done, then by all means do it... but it's still a good idea to install one of these free open source libraries and look at their source code, as it's been in use (in production!) for quite some time now.
I know it's not a direct answer to your question, sorry if it doesn't help you.
Just learning the basics of OpenGL for a class and was looking for something challenging and interesting to try and draw. Any suggestions?
Aiming to photorealism (just plain models, lights, materials, textures, etc.) is one thing, but what is even more interesting in my opinion is demoscene and all kinds of non-photorealistic effects. The idea of a demo is to program some nice animated graphics that automatically change from one effect to another or tell some sort of a story, and have a background music. Here you can find some videos. Just take a look at what some others have done and use your imagination. That's the funniest part of 3D programming in my opinion. Of course what you'll first program would be something extremely simple when compared to those videos on youtube, but everyone has to start from somewhere. Simple also doesn't need to be ugly. Some random suggestions:
mathematical shapes with sin(), cos(), etc.
alpha blending, especially addition blending (glBlendFunc(GL_ONE, GL_ONE);)
terrain rendering
read 3d model data from a file. (Wavefront .OBJ is a relatively simple one)
feedback effects with glCopyTexImage2D, which copies pixels from screen to a texture (in real life you shouldn't use this because it's too slow, but when learning the basics it's ok)
etc...
You might consider building an OBJ viewer. You will get the experience you're looking for, and it's a pretty good project for a beginning 3D graphics programmer, in terms of difficulty.
I believe opengl has built in shapes such as a teapot that you can call and have it draw. For starters, I'd stick with easy shapes like squares, circles, and cones. Try drawing a wireframe model first since that's the easiest, by using either quadstrips ,triangles or just poly lines. After you've gotten that down, learn to set up lighting and materials so you can draw a solid model.
At school we had a very interesting assignement to get started with OpenGL that I will share. The long term goal was to modelize a living room so you basically have to draw:
A table.
Two chairs.
A carpet.
A sofa
Some stuff that you might find interesting to add on the table for
instance a TV!
When you have all the things done, try to polish the scene a little bit by adding some lighting effects!
Hint: for all the objects you simply need to start with a basic rectangle. Then you can construct your scene step by step using translations/rotations.
I am fairly new to openGL. I have a 3d game that I have running, and it seems to go fairly well. What I would like to do is display an image straight onto the screen, and I am not sure the easiest way to do that. My only idea is to draw a rectangle right in front of the screen and use the image as the texture. It seems like there should be an easier way.
This is for menu screens, and things, so if there is a better way to do that as well, please let me know.
I would recommend setting up OpenGL for 2D rendering via gluOrtho2d(); then, load the image into a texture and, as you said, draw it to the screen by creating a polygon and binding the texture to it. A good example can be found here.
You've got the basic idea. The other obvious alternative is to use glDrawPixels() but I think you'll find the texture method has much better performance. If you're feeling frisky, you might also take a look at Pixel Buffer Objects.
Good luck!