rt3DS/source/vshader.v.pica
2023-04-10 15:45:27 -04:00

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.constf myconst(0.0, 1.0, 0.01, 1000.0)
.constf myconst2(0.5, 999.0, 0.0, 0.0)
.alias zeros myconst.xxxx
.alias halfs myconst2.xxxx
.alias ones myconst.yyyy
.alias near myconst.zzzz
.alias far myconst.wwww
.alias noHit myconst2.yyyy
.consti bounceLoopParams(3, 0, 1, 0)
.consti calcSphereLoopParams(2, 0, 1, 0)
.setb b0 true
.alias true b0
; xyz center (in world space)
; w radius (in world space)
.fvec spheres[3]
; material albedo
.fvec sphereColors[3]
; random numbers
.fvec rand[4]
.in inOrigin v0
.in inLowerLeftCorner v1
.in inHorizontal v2
.in inVertical v3
.in inST v4
.in inPos v5
.in inUV v6
.out outPos position
.out outUV texcoord0
.out outColor color
.proc main
; outPos = inPos
mov outPos, inPos
; outUV = inUV
mov outUV, inUV
; r1 = inOrigin
mov r1, inOrigin
; r2 = inDirection
mov r2.xyz, inLowerLeftCorner
mov r3.xy, inST.xy
mad r2.xyz, inHorizontal, r3.x, r2.xyz
mad r2.xyz, inVertical, r3.y, r2.xyz
; set initial color to (1, 1, 1)
; as lights are not implemented yet
mov r4.xyz, ones
; calculate light bounces
for bounceLoopParams
; setup random numbers for this iteration
mov r11, rand[aL]
; reset max ray distance
mov r4.w, far
; set albedo to a large number for sphere hit check
mov r10.xyz, far
; for each sphere
for calcSphereLoopParams
; r3 = spheres[i]
mov r3, spheres[aL]
; do calculation
; call calcSphere
; vec3 oc = origin - center
add r8.xyz, r1.xyz, -r3.xyz
; float a = dot(direction, direction)
dp3 r9.x, r2.xyz, r2.xyz
; float halfB = dot(oc, direction)
dp3 r9.y, r8.xyz, r2.xyz
; float radiusSquared = radius * radius
mul r8.w, r3.w, r3.w
; float c = dot(oc, oc) - radius * radius
dp3 r9.z, r8.xyz, r8.xyz
add r9.z, r9.z, -r8.w
; float halfBSquared = halfB * halfB;
mul r8.w, r9.y, r9.y
; float ac = a * c;
mul r9.w, r9.x, r9.z
; float discriminant = bSquared - ac
add r8.w, r8.w, -r9.w
; if discriminant < 0, exit procedure early
cmp zeros, gt, gt, r8.w
jmpc cmp.x, calcSphereExit
; calculate t
; float sqrtDiscriminant = sqrt(discriminant)
rsq r8.w, r8.w
rcp r8.w, r8.w
; a = 1 / a
rcp r9.x, r9.x
; float root = (-halfB - sqrtDiscriminant) / a
add r9.z, -r9.y, -r8.w
mul r9.z, r9.z, r9.x
; if root < min distance, check other root
cmp near, gt, gt, r9.z
jmpc cmp.x, calcSphereCheckOtherRoot
; if root > max distance, check other root
cmp r9.z, gt, gt, r4.w
jmpc cmp.x, calcSphereCheckOtherRoot
; if root is in range, finalize calculations
jmpu true, calcSphereFin
calcSphereCheckOtherRoot:
; float root = (-halfB + sqrtDiscriminant) / a
add r9.z, -r9.y, r8.w
mul r9.z, r9.z, r9.x
; if root < min distance, check other root
cmp near, gt, gt, r9.z
jmpc cmp.x, calcSphereExit
; if root > max distance, check other root
cmp r9.z, gt, gt, r4.w
jmpc cmp.x, calcSphereExit
calcSphereFin:
; change max distance to closest hit
mov r4.w, r9.z
; calculate new origin
mul r5.xyz, r2.xyz, r9.zzz
add r5.xyz, r5.xyz, r1.xyz
; calculate normal
add r7.xyz, r5.xyz, -r3.xyz
rcp r3.w, r3.w
mul r7.xyz, r7.xyz, r3.w
; set albedo
mov r10.xyz, sphereColors[aL].xyz
; early exit label
calcSphereExit:
nop
; done with calculation
.end
; check if noHit > albedo
cmp noHit.xyz, le, le, r10.xyz
breakc cmp.x
jmpc cmp.x, noHitLabel
; multiply color by albedo
mul r4.xyz, r4.xyz, r10.xyz
; set r1 to new ray origin
mov r1.xyz, r5.xyz
; set r2 to new ray direction
add r2.xyz, r7.xyz, r11.xyz
.end
noHitLabel:
; copy final color to output
mov outColor.xyz, r4.xyz
; set alpha to 1
mov outColor.w, ones
end
.end
; Calculate Sphere Intersection
; -----------------------------
;
; Inputs
; ------
; r1.xyz: ray origin
; r2.xyz: ray direction
; r3.xyz: sphere origin
; r3.w: sphere radius
; r4.w: min distance
; r11.xyzw: random numbers
;
; Outputs
; -------
; r4.w: new min distance
; r10.xyz: albedo
;
; Temporaries
; -----------
; r5.xyz: new origin
; r6.xyz: new direction
; r7.xyz: hit normal
; r8.xyzw: used for calculations
; r9.xyzw: used for calculations