using a GPU for OpenGL on a remote machine seems tricky
The idea was to support systems which don't have GPU's. I think it is rare for cloud services to give you GPU access, because I don't think it's possible to share access to GPU's in the same way as CPU and other resources.
I am also dreaming of a website like shadertoy that let's you program game logic along side your shader.
I think, as eiffie said, one of the main appeals for such a CPU emulator would be to run glsl-style logic alongside the shader, so as to provide you with some state between frames.
Thanks @Syntopia, of course the code was never designed to be used directly. It was just a support layer behind the glsl that the programmer would never see. Here is an example of some C++ compiled from a GLSL shader. The main thing to notice is how vector swizzle .xyzw, .rgba .etc are serialized as permute() function calls:
float sdBox(vec3 p, vec3 b) {
vec3 d = abs(p) - b;
return min(max(d.permute(0), max(d.permute(1), d.permute(2))), 0.0f) + length(max(d, 0.0f));
}
float map(vec3 pos) {
float speed = 1.0f;
vec3 grid = floor(pos);
vec3 gmod = mod(grid, 2.0f);
vec3 rmod = mod(grid, 4.0f) - 2.0f;
float tm = fract(iGlobalTime * speed);
rmod *= cos(tm * PI) - 1.0f;
float g = floor(mod(iGlobalTime * speed, 3.0f));
if (g == 0.0f) {
if (gmod.permute(1) * gmod.permute(0) == 1.0f) {
pos[2] += rmod.permute(0) * rmod.permute(1) * 0.5f;
}
} else if (g == 1.0f) {
if (gmod.permute(1) * gmod.permute(2) == 1.0f) {
pos[0] += rmod.permute(1);
}
} else if (g == 2.0f) {
if (gmod.permute(2) == 0.0f) {
pos[1] += rmod.permute(2) * rmod.permute(0) * 0.5f;
}
}
grid = floor(pos);
pos = pos - grid;
pos = pos * 2.0f - 1.0f;
float len = 0.9f;
float d = sdBox(pos, vec3(len));
bool skip = false;
if (mod(grid.permute(0), 2.0f) == 0.0f && mod(grid.permute(1), 2.0f) == 0.0f) {
skip = true;
}
if (mod(grid.permute(0), 2.0f) == 0.0f && mod(grid.permute(2), 2.0f) == 0.0f) {
skip = true;
}
if (mod(grid.permute(1), 2.0f) == 0.0f && mod(grid.permute(2), 2.0f) == 1.0f) {
skip = true;
}
if (skip) {
d = 100.0f;
vec3 off = vec3(2.0f, 0.0f, 0.0f);
for (int i = 0; i < 3; ++i) {
float a = sdBox(pos + off, vec3(len));
float b = sdBox(pos - off, vec3(len));
d = min(d, min(a, b));
off = off.permute(2, 0, 1);
}
d *= 0.5f;
} else {
d *= 0.8f;
}
return d;
}
vec3 surfaceNormal(vec3 pos) {
vec3 delta = vec3(0.01f, 0.0f, 0.0f);
vec3 normal;
normal[0] = map(pos + delta.permute(0, 1, 2)) - map(pos - delta.permute(0, 1, 2));
normal[1] = map(pos + delta.permute(1, 0, 2)) - map(pos - delta.permute(1, 0, 2));
normal[2] = map(pos + delta.permute(2, 1, 0)) - map(pos - delta.permute(2, 1, 0));
return normalize(normal);
}
float aoc(vec3 origin, vec3 ray) {
float delta = 0.05f;
const int samples = 8;
float r = 0.0f;
for (int i = 1; i <= samples; ++i) {
float t = delta * float(i);
vec3 pos = origin + ray * t;
float dist = map(pos);
float len = abs(t - dist);
r += len * pow(2.0f, -float(i));
}
return r;
}
vec3 mainImage(vec2 uv) {
vec3 eye = normalize(vec3(uv, 1.0f - dot(uv, uv) * 0.33f));
vec3 origin = vec3(0.0f);
eye = eye * yrot(iGlobalTime) * xrot(iGlobalTime);
float speed = 0.5f;
float j = iGlobalTime * speed;
float f = fract(j);
float g = 1.0f - f;
f = f * f * g + (1.0f - g * g) * f;
f = f * 2.0f - 1.0f;
float a = floor(j) + f * floor(mod(j, 2.0f));
float b = floor(j) + f * floor(mod(j + 1.0f, 2.0f));
origin.permute(0) += 0.5f + a;
origin.permute(1) += 0.5f;
origin.permute(2) += 0.5f + b;
float t = 0.0f;
float d = 0.0f;
for (int i = 0; i < 32; ++i) {
vec3 pos = origin + eye * t;
d = map(pos);
t += d;
}
vec3 worldPos = origin + eye * t;
vec3 norm = surfaceNormal(worldPos);
float prod = max(0.0f, dot(norm, -eye));
float amb = 0.0f;
vec3 ref = reflect(eye, norm);
vec3 spec = vec3(0.0f);
prod = pow(1.0f - prod, 2.0f);
vec3 col = vec3(0.1f, 0.3f, 0.5f);
spec *= col;
col = mix(col, spec, prod);
float shade = pow(max(1.0f - amb, 0.0f), 4.0f);
float fog = 1.0f / (1.0f + t * t * 0.2f) / shade;
vec3 final = col;
final = mix(final, vec3(1.0f), fog);
fog = 1.0f / (1.0f + t * t * 0.1f);
return vec3(final * fog);
}
@marius any details about how your float fob thing worked?
November 29, 2009, 12:32:26 AM
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