Keypress Commands
 - ESC to quit
 - P to switch polygon rendering
 - R to switch render mode
 - S to switch render shapes
 - Left_Arrow to strafe left
 - Right_Arrow to strafe right
 - Up_Arrow to move foward
 - Down_Arrow to move back
 - Mouse to look
 - Hold Shift + Mouse Scroll to change ambient intensity
 - Hold Alt + Mouse Scroll to change diffuse intensity
 - Hold Cntrl + Mouse Scroll to change specular intensity
 - Hold Cntrl + Shift + Mouse Scroll to change specular highlight sharpness / shinyness
 - W to switch from constant to varying materials per object
 - C to switch the type of light
 - E to switch the scene and lighting type in the multi-light rendering mode
 - F to switch text soft edges
 - T to switch text outlining
 - G to switch text glow
 - Hold V + Mouse Scroll to change text edge distance (font thickness)
 - Hold B + Mouse Scroll to change text edge alias distance (font fuzziness or blur)
 - Hold N + Mouse Scroll to change outline distance
 - Hold M + Mouse Scroll to change outline thickness
 - Hold H + Mouse Scroll to change glow distance
 - Hold J + Mouse Scroll to change glow alias distance glow fuzziness or blur)
 - O to activate post processing with 3x3, 5x5, and two-step separated 9x9 kernels
 - I to switch between post proccessing modes (0 none, 1 invert, 2 grayscale, 3 3x3 kernels, 4 5x5 kernels, 5 two-step 9x9 kernels)
 - K to switch between 3x3, 5x5, and 9x9 kernels
    - 3x3 kernels (0 unsharp mask, 1 sharpen, 2 emboss, 3 gaussian blur, 4 box blur, 5 edge detect)
    - 5x5 kernels (0 gaussian blur, 1 unsharp mask)
    - 9x9 kernels (0 gaussian blur, 1 lapacian blur, 2 poisson blur, 3 rayleigh blur, 4 spherical blur)
 - Hold A + Mouse Scroll (while 9x9 kernel 0, 1, or 2) to adjust kernel amplitude (kernel bell curve intensity or height)
 - Hold U + Mouse Scroll (while 9x9 kernel 0, 1, or 2) to adjust kernel mu (kernel bell curve center)
 - Hold L + Mouse Scroll (while 9x9 kernel 0, 1, or 2) to adjust kernel sigma (kernel bell curve width)
 - Q to render particles
 - Space to draw multiple instances of geometry
 - Enter to draw vertex normals
 - Y to shift object normals away from surface (inflate objects like balloons)
 - Z to switch blinn-phong specular lighting and phong lighting
 - X to view point shadow depth maps as skybox cubemap (lights 1-4)
 - Hold , + Mouse Scroll to adjust exposure
 - Hold . + Mouse Scroll to adjust gamma correction
 - / to switch rendering to deferred shading (only multi-light example)
 - ' to switch between deferred shading buffer layers (input files rendering during first deferred shading render before lighting)