Fun With Shadows
After completely rewriting and restructuring the code from my custom OpenGL graphics engine which I made in University, this is the first project I pursued. I wanted to fully understand how shadows worked in a graphics pipeline and implement it in an engine of my own.
To do this I needed a terrain for a shadow to be cast onto. Originally I just loaded in a large model for this but I eventually decided to create my own terrain building system.
Features:
Percentage Closer Filtering (PCF) Shadows (A very brief explanation)
First, the scene is rendered from the light's perspective onto a separate Framebuffer as a depth-only pass. This texture is then sent to the shader of all objects which will receive a shadow. In the shader, the vector's world-space position is transformed so it's position is relative to the light position. After some perspective dividing and remapping the co-ordinates to the (0, 1) range, this depth value is compared with the value of the depth texture to determine whether the fragment is in shadow.
The process so far describes regular shadow mapping, PCF shadow mapping adds a few more steps. It takes multiple samples around the point on the shadow map and then takes an average of them. This method results in the emulation of soft shadows.
Frustum shadow box
For the sake of efficiency on larger scenes, the area which is rendered to the shadow map is carefully fit around the viewing frustum of the main camera. Some minor tweaks and adjustments were then made to the size of this box to avoid shadows of offscreen objects popping into existence.
Terrain
The terrain in this projects consists of a grid of points calculated at runtime. the heights of these points are determined by a height map which is read into the program.
The terrain also has support for up to 4 textures which can be blended using a separate texture called a blend map. the red, green, blue and black values from the blend map determine the amount of these textures to be used.
Fog Effect
A bonus feature I added was a simple fog effect. The further away the fragment is from the camera, the stronger the chosen fog colour is mixed.
Implementation
Full code on GitHub -->
