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Ray-cast a translucent sphere

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This commit is contained in:
Aaron Fenyes 2024-08-23 00:16:41 -07:00
parent c78a041dc7
commit d2cecf69db
1 changed files with 52 additions and 29 deletions
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69
app-proto/inversive-display/src/main.rs
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@ -72,6 +72,7 @@ fn main() {
sycamore::render(|| {
let ctrl_x = create_signal(0.0);
let ctrl_y = create_signal(0.0);
let opacity = create_signal(0.6);
let display = create_node_ref();
on_mount(move || {
@ -108,10 +109,17 @@ fn main() {
out vec4 outColor;
// view
uniform vec2 resolution;
uniform float shortdim;
// controls
uniform vec2 ctrl;
uniform float opacity;
// light and camera
const float focal_slope = 0.3;
const vec3 light_dir = normalize(vec3(2., 2., 1.));
struct vecInv {
vec3 sp;
@ -128,8 +136,24 @@ fn main() {
);
}
const float focal_slope = 0.3;
const vec3 light_dir = normalize(vec3(2., 2., 1.));
vec4 shade_sphere(vecInv v, vec3 pt) {
// the expression for normal needs to be checked. it's
// supposed to give the negative gradient of the lorentz
// product between the impact point vector and the sphere
// vector with respect to the coordinates of the impact
// point. i calculated it in my head and decided that
// the result looked good enough for now
vec3 normal_front = normalize(-v.sp + 2.*v.lt.s*pt);
vec3 color;
float incidence = dot(normal_front, light_dir);
if (incidence < 0.) {
color = mix(vec3(0.2, 0.0, 0.4), vec3(0.1, 0.0, 0.2), -incidence);
} else {
color = mix(vec3(0.4, 0.0, 0.2), vec3(1.0, 0.8, 1.0), incidence);
}
return vec4(color, opacity);
}
void main() {
vec2 scr = (2.*gl_FragCoord.xy - resolution) / shortdim;
@ -143,29 +167,20 @@ fn main() {
float scale = -b/(2.*a);
float adjust = 4.*a*c/(b*b);
vec3 color = vec3(0.);
if (adjust < 1.) {
float offset = sqrt(1. - adjust);
float u_front = scale * (1. - offset);
float u_back = scale * (1. + offset);
vec3 color;
if (adjust < 1. && u_front > 0.) {
// the expression for normal needs to be checked. it's
// supposed to give the negative gradient of the lorentz
// product between the impact point vector and the sphere
// vector with respect to the coordinates of the impact
// point. i calculated it in my head and decided that
// the result looked good enough for now
vec3 pt_front = u_front * dir;
vec3 normal_front = normalize(-v.sp + 2.*v.lt.s*pt_front);
float incidence = dot(normal_front, light_dir);
if (incidence < 0.) {
color = mix(vec3(0.2, 0.0, 0.4), vec3(0.1, 0.0, 0.2), -incidence);
} else {
color = mix(vec3(0.4, 0.0, 0.2), vec3(1., 0.8, 1.), incidence);
if (u_back > 0.) {
vec4 sphere_color = shade_sphere(v, u_back * dir);
color = mix(color, sphere_color.rgb, sphere_color.a);
}
if (u_front > 0.) {
vec4 sphere_color = shade_sphere(v, u_front * dir);
color = mix(color, sphere_color.rgb, sphere_color.a);
}
} else {
color = vec3(0.);
}
outColor = vec4(color, 1.);
}
@ -192,6 +207,7 @@ fn main() {
let resolution_loc = ctx.get_uniform_location(&program, "resolution");
let shortdim_loc = ctx.get_uniform_location(&program, "shortdim");
let ctrl_loc = ctx.get_uniform_location(&program, "ctrl");
let opacity_loc = ctx.get_uniform_location(&program, "opacity");
// create a vertex array and bind it to the graphics context
let vertex_array = ctx.create_vertex_array().unwrap();
@ -211,16 +227,17 @@ fn main() {
];
bind_vertex_attrib(&ctx, position_index, 3, &positions);
// set up a repainting routine
create_effect(move || {
// set the resolution
let width = canvas.width() as f32;
let height = canvas.height() as f32;
ctx.uniform2f(resolution_loc.as_ref(), width, height);
ctx.uniform1f(shortdim_loc.as_ref(), width.min(height));
// set up a repainting routine
create_effect(move || {
// pass the control parameters
ctx.uniform2f(ctrl_loc.as_ref(), ctrl_x.get() as f32, ctrl_y.get() as f32);
ctx.uniform1f(opacity_loc.as_ref(), opacity.get() as f32);
// clear the screen and draw the scene
ctx.clear_color(0.0, 0.0, 0.0, 1.0);
@ -246,6 +263,12 @@ fn main() {
step=0.01,
bind:valueAsNumber=ctrl_y
)
input(
type="range",
max=1.0,
step=0.01,
bind:valueAsNumber=opacity
)
}
}
});