Pieter Germishuys

Xilath - Asteroids game update

Xilath - ShaderManager (Nearing completion)

With the Shader

Xilath - Base update

Tests and The Big Mission

Xilath - Game Engine (BSP Loader)

Xilath - Game Engine (Shadowing)

Xilath - Game Engine (Mirrors)

Xilath - Game Engine update

Game Engine design

What a fantastic evening - SaDeveloper Durban Event

Tommorow is the big day.

Tutorial 7 - Render to Texture

[Download the source]
Have you ever seen water reflecting the environment? This can be done with a technique called render to texture. Let's look at what it involves.
What is render to texture?
Render to texture describes the operation of "saving/capturing" a render target (surface)to a texture.

Let's take an example:

The top left hand corner is a sprite rendered with the textured that we have "saved/captured" from a render target (surface).
The steps to follow the render to a texture.
The easiest way of capturing a render target (surface) to a texture is by taking the following steps.
1) Declare a Texture to capture to.
2) Declare a Surface that will be your new render target
3) Get the surface of the texture
4) Save the original back buffer (color buffer) in a temporary surface
5) Set the render target of the device to a
6 ) Render the objects that you want to save into the texture
7) Set the render target to the original render target.

7 easy steps to remember (I hope).

The code
Declaring your objects.

Tutorial 6 - Alpha Blending

[Download the source]
Today we are going to discuss a very interesting topic, Alpha blending.
What is alpha blending?
"The real world is composed of transparent, translucent, and opaque objects. Alpha blending is a technique for adding transparency information for translucent objects. It is implemented by rendering polygons through a stipple mask whose on-off density is proportional to the transparency of the object. The resultant color of a pixel is a combination of the foreground and background color. Typically, alpha has a normalized value of 0 to 1 for each color pixel. new pixel = (alpha)(pixel A color) + (1 - alpha)(pixel B color)"

Let's take an example:

Looks cool doesn't it? This is called alpha blending, where you have a alpha component for each pixel.
How does it work?
Pretty boring stuff
Let's take 2 pixels. One is already in the back buffer (Color buffer) and one is being sent to the back buffer (Color buffer).
Source's Pixel Color (The pixel on the triangle) = (127, 255, 0,    0); //This being an alpha value of 127 (50%) and Red (255), Green(0), Blue(0)
Destination's Pixel Color (The pixel in the back buffer) = (127,    0, 0, 255); //This being an alpha value of 127 (50%) and Red (0), Green(0), Blue(255)

New Pixel Color = Source*Alpha/max_Alpha + Destination*(max_Alpha-Alpha)/max_Alpha
New Pixel Color = 255 * 127/255 + 255 * (255 - 127) / 127
New Pixel Color = 50% Red + 100% Blue (I might be off with the calculation though)
This means the 2 pixels get blended and placed in the back buffer (Color buffer)

How do I make it work?
The interesting stuff
We use the simple set of render states that DirectX so happily offers us.

Xilath - The Class Diagram

Managed DirectX and C# - Temple Demo