Just add

1
Just add

• Water

2
Early Attempt

• Per-Vertex sinusoidal warping of position
• Per-Vertex sinusoidal warping of normal
• All Lighting Per-Vertex
• VS/PS 1

3
Next Attempt

• Still VS/PS1
• Per-Vertex creation of Tangent-Space Basis
• Scrolling Normal-Map coordinates (scrolled in VS)
• Normal-Map sampled in PS, then put in world-space
  and reflected to sample Environment Map
• This is possible with the magic PS
  instructionstexm3x3pad t1, t0_bx2texm3x3pad t2
  , t0_bx2texm3x3vspec t3, t0_bx2
• This performs a 3x3 matrix multiply, reflection,
  and cube-map lookup AMAZING!
• This is impossible to do without dropping into
  the assembly-style shader programming

4
Next Attempt (cont.)

• Additionally, some per-vertex light color
  computation (Gouraud-style)
• Also added reflection-map, perturbed in VS and
  sampled in PS using a second pass
• This required rendering the reflected scene to a
  dynamic texture, and implementing per-pixel
  clipping using the instruction tex-kill
  (simulated user-clip planes)
• This texture is the reflection-map, which is
  then projectively-textured onto the water geometry

5
3rd Times the Charm

• VS/PS 2 (ahh more than 8 instructions in the
  pixel shader! Yay!)
• No more sin/cos stuff
• 4 scrolling bump maps, scrolled in different
  directions and speeds
• Reflection Map (render to texture, 1st pass)
• Refraction Map (render to texture, 2nd pass)
• Real User Clip Planes
• When using Fixed-Function Pipeline, user clip
  planes are expected to be in World Space
• When using Programmable Pipeline, user clip
  planes are expected to be in Clip Space go
  figure! Good ol DirectX

6
3rd Times the Charm (cont.)

• Render everything for real, and then draw water
  using reflection and refraction maps (3rd pass)
• All perturbation occurs in pixel-shader
• All 4 scrolling normal maps are sampled, the
  normals summed and normalized into single normal
• Projective reflection and refraction map
  coordinates are perturbed by this normal
• each is perturbed with a different scaling factor
• Reflection and refraction maps are sampled and
  combined with their respective water color

7
3rd Times the Charm (cont.)

• Fresnel term is calculated using the angle
  between the normal and the view vector
• Creates for much more realistic transparency
  and lighting effects
• Fresnel term defines the blending factor between
  reflection and refraction map
• Looking straight down at water, water should look
  clear
• Looking across/from the side, water should be
  highly reflective

8
Where the Water Meets the Sky

• Sky Dome
• Needs sphere geometry
• Possible with VS/PS1 in a single pass for sky
  color, sun, and moon
• Uses projective texturing for sun and moon
• Additional Normal mapping for moon
• ADDSMOOTH color blending for sun
• Prevents overflow for highly saturated colors
  when using additive blending
• Instead of usual blending of ONESRC ONEDEST
• Uses ONESRC DESTINVSRC
• Base sky color uses simple 1D gradient function
• Atmospheric color scattering performed in Vertex
  Shader