Lua code which hardcodes a glsl raytracer demo
Posted: Wed Feb 24, 2016 12:21 am
Okay. So I thought, "wouldn't it be fun if I wrote a Lua program to program a hardcoded binary search tree in GLSL?" So I did it, and then before I implemented stuff other than the sphere solver, I realized that you only have a small number of words for gpu instructions to be stored. So you can't actually go over like 200 spheres in my raycaster...
ANYWAY, here's the code.
ANYWAY, here's the code.
Code: Select all
--How to create the raycast GLSL code
-- call generateglslcaster(data)
-- returns a string of glsl code
-- the code contains a function called raycast
--How to call the raycast function
--bool raycast(in vec3 o,in vec3 d,out vec3 pos,out vec3 norm,out vec4 color)
-- Returns whether the ray hit anything
-- o is the origin of the ray
-- d is the direction of the ray
-- pos is where the ray hits the object
-- norm is the normal of where the ray hits the object
-- color is the color of the object the ray hit
--Groups nearest spheres together
--This make a log-time ray search
--Way better than octrees... if you don't need to move anything.
local function partition(spheres)
if #spheres==1 then
return spheres[1]
else
local newspheres={}
local taken={}
for i=1,#spheres do
if not taken[i] then
local b0=spheres[i]
local bestr=1/0
local bestj
for j=i+1,#spheres do
if not taken[j] then
local b1=spheres[j]
local r
local d=((b1.x-b0.x)*(b1.x-b0.x)
+(b1.y-b0.y)*(b1.y-b0.y)
+(b1.z-b0.z)*(b1.z-b0.z))^0.5
if d+b0.r<b1.r then
r=b1.r
elseif d+b1.r<b0.r then
r=b0.r
else
r=(d+b0.r+b1.r)/2
end
if r<bestr then
bestr=r
bestj=j
end
end
end
if bestj then
taken[i]=true
taken[bestj]=true
local b1=spheres[bestj]
local d=((b1.x-b0.x)*(b1.x-b0.x)
+(b1.y-b0.y)*(b1.y-b0.y)
+(b1.z-b0.z)*(b1.z-b0.z))^0.5
if d+b0.r<b1.r then
newspheres[#newspheres+1]={
a=b0;
b=b1;
x=b1.x;
y=b1.y;
z=b1.z;
r=b1.r;
}
elseif d+b1.r<b0.r then
newspheres[#newspheres+1]={
a=b0;
b=b1;
x=b0.x;
y=b0.y;
z=b0.z;
r=b0.r;
}
else
local c0=((b0.r-b1.r)/d+1)/2
local c1=((b1.r-b0.r)/d+1)/2
newspheres[#newspheres+1]={
a=b0;
b=b1;
x=c0*b0.x+c1*b1.x;
y=c0*b0.y+c1*b1.y;
z=c0*b0.z+c1*b1.z;
r=bestr;
}
end
end
end
end
for i=1,#spheres do
if not taken[i] then
newspheres[#newspheres+1]=spheres[i]
end
end
return partition(newspheres)
end
end
--Bounds all the objects into minimum size spheres.
--Because the only datatype is sphere, this is kind of useless, but whatever.
--I _was_ planning on adding more shapes
local function makespheres(data)
local spheres={}
for i=1,#data do
local g=data[i]
if g.type=="sphere" then
spheres[i]={
x=g.cx;
y=g.cy;
z=g.cz;
r=g.r;
g=g;
}
end
end
return spheres
end
--code to check if the ray intersects a partition sphere
local pcheck=[[
$tco=$c-o;
$tu=dot(d,co);
$tv2=u*u-dot(co,co)+$r;
$tif(0<v2&&0<u+sqrt(v2)&&u-sqrt(v2)<bestt){
$t //Optimization: &&0<u+sqrt(v2)&&u-sqrt(v2)<bestt
$t //I haven't tested it but I think square roots are significantly faster than more if statements
]]
--Solves the intersection of the ray and a sphere object
--sets hit distance, hit position, hit norm, and color
local solvesphere=[[
$t vec3 co=$c-o;
$t float u=dot(d,co);
$t float v2=u*u-dot(co,co)+$r;
$t if(0<v2){
$t float t=u-sqrt(v2);
$t if(0<t&&t<bestt){
$t bestt=t;
$t pos=o+t*d;
$t norm=normalize(pos-$c);
$t color=$q;
$t }
$t }
]]
--recursively hardcodes the partition checks and object solvers.
local function writecode(p,tabs)
tabs=(tabs or "").."\t"
local s0=string.gsub(pcheck,"$(.)",function(c)
if c=="c" then
return "vec3("..p.x..","..p.y..","..p.z..")"
elseif c=="r" then
return p.r*p.r
elseif c=="t" then
return tabs
end
end)
local g=p.g
if g then
if g.type=="sphere" then
local s1=string.gsub(solvesphere,"$(.)",function(c)
if c=="c" then
return "vec3("..g.cx..","..g.cy..","..g.cz..")"
elseif c=="r" then
return g.r*g.r
elseif c=="t" then
return tabs
elseif c=="q" then
return "vec4("..g.cr..","..g.cg..","..g.cb..",1)"
end
end)
return s0..s1..tabs.."}\n"
--elseif g.type=="convexmesh" then LOLOLOL Not going to happen
end
else
return s0..writecode(p.a,tabs)..writecode(p.b,tabs)..tabs.."}\n"
end
end
--Makes the glsl ray caster from the given data
local function generateglslcaster(data)
local part=partition(makespheres(data))
return [[
bool raycast(in vec3 o,in vec3 d,out vec3 pos,out vec3 norm,out vec4 color){
d=normalize(d);
float bestt=1.0f/0.0f;
vec3 co;
float u;
float v2;
]]..writecode(part)..[[
return bestt<1.0/0.0;
}
]]
end
--Trash code after this point.
--Make a bunch of spheres.
local data={}
for i=1,64 do
--shitty non-uniform distribution.
local cx=math.random()-0.5
local cy=math.random()-0.5
local cz=math.random()-0.5
local c=7.5/(cx*cx+cy*cy+cz*cz)^0.5
cx,cy,cz=c*cx,c*cy,c*cz
data[i]={
type="sphere";
cx=cx;
cy=cy;
cz=cz;
cr=math.random();
cg=math.random();
cb=math.random();
r=math.random();
}
end
data[65]={
type="sphere";
cx=0;
cy=0;
cz=0;
cr=0.25;
cg=0.25;
cb=0.75;
r=5;
}
--Create the caster
local caster=generateglslcaster(data)
--Create the tracer
--This is the part you rewrite to make less cruddy
local effecttracer=[[
extern float w=800;
extern float h=600;
extern vec3 cp=vec3(0,0,0);
extern vec3 cx=vec3(1,0,0);
extern vec3 cy=vec3(0,1,0);
extern vec3 cz=vec3(0,0,1);
extern vec3 lightdir=normalize(vec3(1,1,1));
vec4 effect( vec4 _color, Image texture, vec2 p, vec2 screen_coords )
{
vec3 throwaway3;
vec4 throwaway4;
vec3 pos=cp;
//Notice how I'm not subtracting cz. It's because left hand rule is for cool peeps.
vec3 dir=w/h*(2*p.x-1)*cx+(1-2*p.y)*cy+cz;
vec3 norm;
vec4 color;
vec4 sumcolor=vec4(0,0,0,1);
vec4 mulcolor=vec4(1,1,1,1);
for(int i=0;i<10;i++){
bool hit=raycast(pos,dir,pos,norm,color);
if(!hit){
return sumcolor;
}
//Some craptastic light stuff.
hit=raycast(pos,lightdir,throwaway3,throwaway3,throwaway4);
if(!hit){
sumcolor+=0.5*max(0,dot(norm,lightdir))*mulcolor*color;
}
mulcolor*=color;
dir-=2*dot(dir,norm)*norm;
}
return sumcolor;
}
]]
--Compile the fragment shader
local effect=love.graphics.newShader(caster..effecttracer)
--In case you want to do something cool, hve a canvas
local canvas=love.graphics.newCanvas(800,600,"hdr")
love.graphics.setShader(effect)
--Position and angles... sort of.
local pos={10,10,10}
local mx,my=0,0
local sin=math.sin
local cos=math.cos
local function anglesyx(x,y)
local cx,sx=cos(x),sin(x)
local cy,sy=cos(y),sin(y)
--Inefficient. Oh well. This is trash code.
return {cy,0,-sy},{sx*sy,cx,cy*sx},{cx*sy,-sx,cx*cy}
end
function love.draw()
love.graphics.draw(canvas)
end
love.mouse.setRelativeMode(true)
function love.mousemoved(x,y,dx,dy)
mx=mx+dx
my=my+dy
local cx,cy,cz=anglesyx(my/256,mx/256)
effect:send("cx",cx)
effect:send("cy",cy)
effect:send("cz",cz)
end
local t=0
function love.update(dt)
t=t+dt
effect:send("lightdir",{0.5^0.5*sin(t),0.5^0.5,0.5^0.5*cos(t)})
if love.keyboard.isDown("escape") then
love.event.quit()
end
local cx,cy,cz=anglesyx(my/256,mx/256)
local dx=0;
local dz=0;
if love.keyboard.isDown("w") then
dz=dz+1
end
if love.keyboard.isDown("a") then
dx=dx-1
end
if love.keyboard.isDown("s") then
dz=dz-1
end
if love.keyboard.isDown("d") then
dx=dx+1
end
local d2=dx*dx+dz*dz
if 0<d2 then
local d=d2^0.5
dx=dx/d
dz=dz/d
end
if love.keyboard.isDown("lshift") then
dx=dx/16
dz=dz/16
end
pos[1]=pos[1]+dt*4*(dx*cx[1]+dz*cz[1])
pos[2]=pos[2]+dt*4*(dx*cx[2]+dz*cz[2])
pos[3]=pos[3]+dt*4*(dx*cx[3]+dz*cz[3])
effect:send("cp",pos)
end
lol