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Just add

Just add. Water. Early Attempt. Per-Vertex sinusoidal warping of position Per-Vertex sinusoidal warping of normal All Lighting Per-Vertex VS/PS 1. Next Attempt. Still VS/PS1 Per-Vertex creation of “Tangent-Space” Basis Scrolling Normal-Map coordinates (scrolled in VS)

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Just add

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  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 Time’s 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 Time’s 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 Time’s 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 ONE*SRC + ONE*DEST • Uses ONE*SRC + DEST*INVSRC • Base sky color uses simple 1D gradient function • Atmospheric color scattering performed in Vertex Shader

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