Sunday, April 19, 2009

Boxes, Cylinders, and Spheres (Oh My!)

After deciding to use PhysX in combination with DirectX 11 last week, I thought about how I would go about drawing simple 3D shapes. In the samples and lessons, PhysX uses GLUT with has some shape drawing functions built-in. While DX9 has similar functions, neither DX10 nor XNA do. I believe it is safe to assume that DX11 will not have them either. I can understand why they were removed. They don't really make sense anymore in a programmable pipeline system. What is the vertex format of the shape created?

While most people these days get around it by creating a mesh in a 3D modeling application and then importing it into their game, I prefer to have my simple 3D shapes constructed programatically. This allows me to easily change the detail of the mesh without worrying about exporting/importing an entire new model.

Instead of implementing it in DX10 and C++ first, I decided to implement it in XNA. This allowed me to focus on the algorithms themselves and not have to worry about any C++ issues getting in the way.

My initial implementation was a static class that had static methods in it that built the shapes and returned the vertex buffer and index buffer. This worked well, but I thought it still placed too much burden on the user to remember how many vertices they had just created and how many triangles they were going to draw.

In order to make things simpler, I changed it to be a normal, instantiated class that contained the static methods that created an instance of the class. This allowed me to store the vertex count, triangle count, as well as the buffers in instance properties in the class. I even threw in a Draw method to make it incredibly simple to use the generated shape.

Because this is such a basic, fundamental class that can benefit several people ( have seen various people requesting something like this), I have decided to share it with the public.

You may download the C# file from here:

You can also download the entire test project here:

To use, simply create a shape using one of the static methods:
Shape3D sphere = Shape3D.CreateSphere(GraphicsDevice, 1, 12, 12);

To draw, in your Effect block, call the Draw method on the shape:

The Create methods are made to follow the same structure as the DX9 shape drawing functions. You can read more about those here:

Sunday, April 12, 2009

Tactical RPG

I've been engrossed with learning about DX11 lately. I've looked at slide presentations, listened to audio recordings of speeches, and read various articles discussing the new features being introduced. I believe it's a great understatement to say that I'm excited about DX11. I've finally come to the conclusion that once I have a DX11 GPU, I'm going to rewrite my procedural planet code using DX11.

In the meantime, I've decided to take about 1 month to implement a prototype for a tactical RPG I've been thinking about. I started about 2 weeks ago, and I plan to finish it by the end of April. One of my main goals is to have it completely mouse driven so that it can be played on a tablet.

I believe it is coming along rather well. I have a really nice 2D camera set up that behaves similar to Google Maps. You can use the mouse to drag around the view and you can zoom in and out using the scroll wheel. I have basic movement and attacking implemented as well. I even have one of my graphic designer friends making up some art for me. Overall, it should shape up to be a pretty decent prototype. Maybe I will even release it to the public, source and all.


New content for Banjo-Kazooie: Nuts & Bolts was released last week. As a result, I pulled out the game again and played it some more. I wasted several hours just messing around with the vehicle editor to make various contraptions. I started thinking about how much fun it was to just tinker around like that without really following any goals, and then I started wondering about how hard it would be to implement a similar system myself.

Almost 4 years ago, I had implemented a "domino simulator" using what was then known as the NovodeX physics engine. It is now known as PhysX, is owned by Nvidia, and has hardware acceleration. So, I downloaded the SDK and played around with some of the samples.

First, the good. I was simply astounded by how many samples were provided in the SDK. There are 37 samples and 89 "lessons", all with documentation. It is amazing. Plus, the hardware acceleration really helps speed the physics engine up. One of the samples was getting about 40fps in software mode and 130fps in hardware mode. That was on a 9800M GT.

The bad is more about C++ than PhysX. I decided to create a C++ project from scratch and then add all of the libraries and code necessary to get the first lesson from the SDK working. It was horrific. It took me 3 hours to get everything to compile and run. In the end, here is what was in my project:

5 include directories
3 static libraries
- added to both the project and VS itself
- had to add one directly to solution to get to compile
12 include files (separate from the include directories)
8 cpp files
1 dll

Remember, all of that was to run the FIRST lesson, which is just three shapes on a plane. In C#, it would have been 3-4 DLLs and one CS file. As I said, this is more of a complaint about C++ and not PhysX. I forgot how tedious it was to setup a project for the first time. I do plan to stick with PhysX though, because once I do port my procedural planet code over to C++/DX11, then I will want a nice physics engine to go along with it, and it might was well be the only one with hardware acceleration.

Until next time...