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Display: bring in ray-casting code

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This commit is contained in:
Aaron Fenyes 2024-09-14 11:46:24 -07:00
parent 49655a8d62
commit cd18d594e0
5 changed files with 583 additions and 6 deletions
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11
app-proto/sketch-outline/Cargo.toml
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@ -9,6 +9,7 @@ default = ["console_error_panic_hook"]
[dependencies]
itertools = "0.13.0"
js-sys = "0.3.70"
nalgebra = "0.33.0"
sycamore = "0.9.0-beta.3"
@ -20,6 +21,16 @@ console_error_panic_hook = { version = "0.1.7", optional = true }
[dependencies.web-sys]
version = "0.3.69"
features = [
'HtmlCanvasElement',
'Performance',
'WebGl2RenderingContext',
'WebGlBuffer',
'WebGlProgram',
'WebGlShader',
'WebGlUniformLocation',
'WebGlVertexArrayObject'
]
[dev-dependencies]
wasm-bindgen-test = "0.3.34"

340
app-proto/sketch-outline/src/display.rs
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@ -1,10 +1,342 @@
use sycamore::prelude::*;
use core::array;
use nalgebra::{DMatrix, DVector, Rotation3, Vector3};
use sycamore::{prelude::*, motion::create_raf};
use web_sys::{
console,
window,
WebGl2RenderingContext,
WebGlProgram,
WebGlShader,
WebGlUniformLocation,
wasm_bindgen::{JsCast, JsValue}
};
fn compile_shader(
context: &WebGl2RenderingContext,
shader_type: u32,
source: &str,
) -> WebGlShader {
let shader = context.create_shader(shader_type).unwrap();
context.shader_source(&shader, source);
context.compile_shader(&shader);
shader
}
fn get_uniform_array_locations<const N: usize>(
context: &WebGl2RenderingContext,
program: &WebGlProgram,
var_name: &str,
member_name_opt: Option<&str>
) -> [Option<WebGlUniformLocation>; N] {
array::from_fn(|n| {
let name = match member_name_opt {
Some(member_name) => format!("{var_name}[{n}].{member_name}"),
None => format!("{var_name}[{n}]")
};
context.get_uniform_location(&program, name.as_str())
})
}
// load the given data into the vertex input of the given name
fn bind_vertex_attrib(
context: &WebGl2RenderingContext,
index: u32,
size: i32,
data: &[f32]
) {
// create a data buffer and bind it to ARRAY_BUFFER
let buffer = context.create_buffer().unwrap();
context.bind_buffer(WebGl2RenderingContext::ARRAY_BUFFER, Some(&buffer));
// load the given data into the buffer. the function `Float32Array::view`
// creates a raw view into our module's `WebAssembly.Memory` buffer.
// allocating more memory will change the buffer, invalidating the view.
// that means we have to make sure we don't allocate any memory until the
// view is dropped
unsafe {
context.buffer_data_with_array_buffer_view(
WebGl2RenderingContext::ARRAY_BUFFER,
&js_sys::Float32Array::view(&data),
WebGl2RenderingContext::STATIC_DRAW,
);
}
// allow the target attribute to be used
context.enable_vertex_attrib_array(index);
// take whatever's bound to ARRAY_BUFFER---here, the data buffer created
// above---and bind it to the target attribute
//
// https://developer.mozilla.org/en-US/docs/Web/API/WebGLRenderingContext/vertexAttribPointer
//
context.vertex_attrib_pointer_with_i32(
index,
size,
WebGl2RenderingContext::FLOAT,
false, // don't normalize
0, // zero stride
0, // zero offset
);
}
#[component]
pub fn Display() -> View {
// canvas
let display = create_node_ref();
// navigation
let pitch_up = create_signal(0.0);
let pitch_down = create_signal(0.0);
let yaw_right = create_signal(0.0);
let yaw_left = create_signal(0.0);
let roll_ccw = create_signal(0.0);
let roll_cw = create_signal(0.0);
let zoom_in = create_signal(0.0);
let zoom_out = create_signal(0.0);
// change listener
let scene_changed = create_signal(true);
/* INSTRUMENTS */
const SAMPLE_PERIOD: i32 = 60;
let mut last_sample_time = 0.0;
let mut frames_since_last_sample = 0;
let mean_frame_interval = create_signal(0.0);
on_mount(move || {
/* SCAFFOLDING */
/* create list of construction elements */
const SPHERE_MAX: usize = 200;
let mut sphere_vec = Vec::<DVector<f64>>::new();
let mut color_vec = Vec::<[f32; 3]>::new();
// timing
let mut last_time = 0.0;
// viewpoint
const ROT_SPEED: f64 = 0.4; // in radians per second
const ZOOM_SPEED: f64 = 0.15; // multiplicative rate per second
let mut orientation = DMatrix::<f64>::identity(5, 5);
let mut rotation = DMatrix::<f64>::identity(5, 5);
let mut location_z: f64 = 5.0;
// display parameters
const OPACITY: f32 = 0.5; /* SCAFFOLDING */
const HIGHLIGHT: f32 = 0.2; /* SCAFFOLDING */
const LAYER_THRESHOLD: i32 = 0; /* DEBUG */
const DEBUG_MODE: i32 = 0; /* DEBUG */
/* INSTRUMENTS */
let performance = window().unwrap().performance().unwrap();
// get the display canvas
let canvas = display.get().unchecked_into::<web_sys::HtmlCanvasElement>();
let ctx = canvas
.get_context("webgl2")
.unwrap()
.unwrap()
.dyn_into::<WebGl2RenderingContext>()
.unwrap();
// compile and attach the vertex and fragment shaders
let vertex_shader = compile_shader(
&ctx,
WebGl2RenderingContext::VERTEX_SHADER,
include_str!("identity.vert"),
);
let fragment_shader = compile_shader(
&ctx,
WebGl2RenderingContext::FRAGMENT_SHADER,
include_str!("inversive.frag"),
);
let program = ctx.create_program().unwrap();
ctx.attach_shader(&program, &vertex_shader);
ctx.attach_shader(&program, &fragment_shader);
ctx.link_program(&program);
let link_status = ctx
.get_program_parameter(&program, WebGl2RenderingContext::LINK_STATUS)
.as_bool()
.unwrap();
let link_msg = if link_status {
"Linked successfully"
} else {
"Linking failed"
};
console::log_1(&JsValue::from(link_msg));
ctx.use_program(Some(&program));
/* DEBUG */
// print the maximum number of vectors that can be passed as
// uniforms to a fragment shader. the OpenGL ES 3.0 standard
// requires this maximum to be at least 224, as discussed in the
// documentation of the GL_MAX_FRAGMENT_UNIFORM_VECTORS parameter
// here:
//
// https://registry.khronos.org/OpenGL-Refpages/es3.0/html/glGet.xhtml
//
// there are also other size limits. for example, on Aaron's
// machine, the the length of a float or genType array seems to be
// capped at 1024 elements
console::log_2(
&ctx.get_parameter(WebGl2RenderingContext::MAX_FRAGMENT_UNIFORM_VECTORS).unwrap(),
&JsValue::from("uniform vectors available")
);
// find indices of vertex attributes and uniforms
let position_index = ctx.get_attrib_location(&program, "position") as u32;
let sphere_cnt_loc = ctx.get_uniform_location(&program, "sphere_cnt");
let sphere_sp_locs = get_uniform_array_locations::<SPHERE_MAX>(
&ctx, &program, "sphere_list", Some("sp")
);
let sphere_lt_locs = get_uniform_array_locations::<SPHERE_MAX>(
&ctx, &program, "sphere_list", Some("lt")
);
let color_locs = get_uniform_array_locations::<SPHERE_MAX>(
&ctx, &program, "color_list", None
);
let resolution_loc = ctx.get_uniform_location(&program, "resolution");
let shortdim_loc = ctx.get_uniform_location(&program, "shortdim");
let opacity_loc = ctx.get_uniform_location(&program, "opacity");
let highlight_loc = ctx.get_uniform_location(&program, "highlight");
let layer_threshold_loc = ctx.get_uniform_location(&program, "layer_threshold");
let debug_mode_loc = ctx.get_uniform_location(&program, "debug_mode");
// create a vertex array and bind it to the graphics context
let vertex_array = ctx.create_vertex_array().unwrap();
ctx.bind_vertex_array(Some(&vertex_array));
// set the vertex positions
const VERTEX_CNT: usize = 6;
let positions: [f32; 3*VERTEX_CNT] = [
// northwest triangle
-1.0, -1.0, 0.0,
-1.0, 1.0, 0.0,
1.0, 1.0, 0.0,
// southeast triangle
-1.0, -1.0, 0.0,
1.0, 1.0, 0.0,
1.0, -1.0, 0.0
];
bind_vertex_attrib(&ctx, position_index, 3, &positions);
// set up a repainting routine
let (_, start_animation_loop, _) = create_raf(move || {
// get the time step
let time = performance.now();
let time_step = 0.001*(time - last_time);
last_time = time;
// get the navigation state
let pitch_up_val = pitch_up.get();
let pitch_down_val = pitch_down.get();
let yaw_right_val = yaw_right.get();
let yaw_left_val = yaw_left.get();
let roll_ccw_val = roll_ccw.get();
let roll_cw_val = roll_cw.get();
let zoom_in_val = zoom_in.get();
let zoom_out_val = zoom_out.get();
// update the assembly's orientation
let ang_vel = {
let pitch = pitch_up_val - pitch_down_val;
let yaw = yaw_right_val - yaw_left_val;
let roll = roll_ccw_val - roll_cw_val;
if pitch != 0.0 || yaw != 0.0 || roll != 0.0 {
ROT_SPEED * Vector3::new(-pitch, yaw, roll).normalize()
} else {
Vector3::zeros()
}
};
let mut rotation_sp = rotation.fixed_view_mut::<3, 3>(0, 0);
rotation_sp.copy_from(
Rotation3::from_scaled_axis(time_step * ang_vel).matrix()
);
orientation = &rotation * &orientation;
// update the assembly's location
let zoom = zoom_out_val - zoom_in_val;
location_z *= (time_step * ZOOM_SPEED * zoom).exp();
if scene_changed.get() {
/* INSTRUMENTS */
// measure mean frame interval
frames_since_last_sample += 1;
if frames_since_last_sample >= SAMPLE_PERIOD {
mean_frame_interval.set((time - last_sample_time) / (SAMPLE_PERIOD as f64));
last_sample_time = time;
frames_since_last_sample = 0;
}
// find the map from construction space to world space
let location = {
let u = -location_z;
DMatrix::from_column_slice(5, 5, &[
1.0, 0.0, 0.0, 0.0, 0.0,
0.0, 1.0, 0.0, 0.0, 0.0,
0.0, 0.0, 1.0, 0.0, u,
0.0, 0.0, 2.0*u, 1.0, u*u,
0.0, 0.0, 0.0, 0.0, 1.0
])
};
let construction_to_world = &location * &orientation;
// update the construction
sphere_vec.clear();
sphere_vec.push(&construction_to_world * DVector::<f64>::from_column_slice(&[0.5, 0.5, 0.0, 0.5, -0.25]));
sphere_vec.push(&construction_to_world * DVector::<f64>::from_column_slice(&[-0.5, -0.5, 0.0, 0.5, -0.25]));
sphere_vec.push(&construction_to_world * DVector::<f64>::from_column_slice(&[0.0, 0.0, 0.0, 0.4, -0.625]));
color_vec.clear();
color_vec.push([1.00_f32, 0.25_f32, 0.00_f32]);
color_vec.push([0.00_f32, 0.25_f32, 1.00_f32]);
color_vec.push([0.75_f32, 0.75_f32, 0.75_f32]);
// 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));
// pass the construction
ctx.uniform1i(sphere_cnt_loc.as_ref(), sphere_vec.len() as i32);
for n in 0..sphere_vec.len() {
let v = &sphere_vec[n];
ctx.uniform3f(
sphere_sp_locs[n].as_ref(),
v[0] as f32, v[1] as f32, v[2] as f32
);
ctx.uniform2f(
sphere_lt_locs[n].as_ref(),
v[3] as f32, v[4] as f32
);
ctx.uniform3fv_with_f32_array(
color_locs[n].as_ref(),
&color_vec[n]
);
}
// pass the display parameters
ctx.uniform1f(opacity_loc.as_ref(), OPACITY);
ctx.uniform1f(highlight_loc.as_ref(), HIGHLIGHT);
ctx.uniform1i(layer_threshold_loc.as_ref(), LAYER_THRESHOLD);
ctx.uniform1i(debug_mode_loc.as_ref(), DEBUG_MODE);
// draw the scene
ctx.draw_arrays(WebGl2RenderingContext::TRIANGLES, 0, VERTEX_CNT as i32);
// clear the scene change flag
scene_changed.set(false);
} else {
frames_since_last_sample = 0;
mean_frame_interval.set(-1.0);
}
});
start_animation_loop();
});
view! {
/* [TO DO] switch back to integer-valued parameters when that becomes
possible again */
canvas(width="750", height="750", tabindex="0")
/* TO DO */
// switch back to integer-valued parameters when that becomes possible
// again
canvas(ref=display, width="750", height="750", tabindex="0")
}
}

7
app-proto/sketch-outline/src/identity.vert Normal file
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@ -0,0 +1,7 @@
#version 300 es
in vec4 position;
void main() {
gl_Position = position;
}

227
app-proto/sketch-outline/src/inversive.frag Normal file
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@ -0,0 +1,227 @@
#version 300 es
precision highp float;
out vec4 outColor;
// --- inversive geometry ---
struct vecInv {
vec3 sp;
vec2 lt;
};
// --- uniforms ---
// construction. the SPHERE_MAX array size seems to affect frame rate a lot,
// even though we should only be using the first few elements of each array
const int SPHERE_MAX = 200;
uniform int sphere_cnt;
uniform vecInv sphere_list[SPHERE_MAX];
uniform vec3 color_list[SPHERE_MAX];
// view
uniform vec2 resolution;
uniform float shortdim;
// controls
uniform float opacity;
uniform float highlight;
uniform int layer_threshold;
uniform bool debug_mode;
// light and camera
const float focal_slope = 0.3;
const vec3 light_dir = normalize(vec3(2., 2., 1.));
const float ixn_threshold = 0.005;
const float INTERIOR_DIMMING = 0.7;
// --- sRGB ---
// map colors from RGB space to sRGB space, as specified in the sRGB standard
// (IEC 61966-2-1:1999)
//
// https://www.color.org/sRGB.pdf
// https://www.color.org/chardata/rgb/srgb.xalter
//
// in RGB space, color value is proportional to light intensity, so linear
// color-vector interpolation corresponds to physical light mixing. in sRGB
// space, the color encoding used by many monitors, we use more of the value
// interval to represent low intensities, and less of the interval to represent
// high intensities. this improves color quantization
float sRGB(float t) {
if (t <= 0.0031308) {
return 12.92*t;
} else {
return 1.055*pow(t, 5./12.) - 0.055;
}
}
vec3 sRGB(vec3 color) {
return vec3(sRGB(color.r), sRGB(color.g), sRGB(color.b));
}
// --- shading ---
struct taggedFrag {
int id;
vec4 color;
vec3 pt;
vec3 normal;
};
taggedFrag[2] sort(taggedFrag a, taggedFrag b) {
taggedFrag[2] result;
if (a.pt.z > b.pt.z) {
result[0] = a;
result[1] = b;
} else {
result[0] = b;
result[1] = a;
}
return result;
}
taggedFrag sphere_shading(vecInv v, vec3 pt, vec3 base_color, int id) {
// 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 = normalize(-v.sp + 2.*v.lt.s*pt);
float incidence = dot(normal, light_dir);
float illum = mix(0.4, 1.0, max(incidence, 0.0));
return taggedFrag(id, vec4(illum * base_color, opacity), pt, normal);
}
// --- ray-casting ---
// if `a/b` is less than this threshold, we approximate `a*u^2 + b*u + c` by
// the linear function `b*u + c`
const float DEG_THRESHOLD = 1e-9;
// the depths, represented as multiples of `dir`, where the line generated by
// `dir` hits the sphere represented by `v`. if both depths are positive, the
// smaller one is returned in the first component. if only one depth is
// positive, it could be returned in either component
vec2 sphere_cast(vecInv v, vec3 dir) {
float a = -v.lt.s * dot(dir, dir);
float b = dot(v.sp, dir);
float c = -v.lt.t;
float adjust = 4.*a*c/(b*b);
if (adjust < 1.) {
// as long as `b` is non-zero, the linear approximation of
//
// a*u^2 + b*u + c
//
// at `u = 0` will reach zero at a finite depth `u_lin`. the root of the
// quadratic adjacent to `u_lin` is stored in `lin_root`. if both roots
// have the same sign, `lin_root` will be the one closer to `u = 0`
float square_rect_ratio = 1. + sqrt(1. - adjust);
float lin_root = -(2.*c)/b / square_rect_ratio;
if (abs(a) > DEG_THRESHOLD * abs(b)) {
return vec2(lin_root, -b/(2.*a) * square_rect_ratio);
} else {
return vec2(lin_root, -1.);
}
} else {
// the line through `dir` misses the sphere completely
return vec2(-1., -1.);
}
}
void main() {
vec2 scr = (2.*gl_FragCoord.xy - resolution) / shortdim;
vec3 dir = vec3(focal_slope * scr, -1.);
// cast rays through the spheres
const int LAYER_MAX = 12;
taggedFrag frags [LAYER_MAX];
int layer_cnt = 0;
for (int id = 0; id < sphere_cnt; ++id) {
// find out where the ray hits the sphere
vec2 hit_depths = sphere_cast(sphere_list[id], dir);
// insertion-sort the fragments we hit into the fragment list
float dimming = 1.;
for (int side = 0; side < 2; ++side) {
float hit_z = -hit_depths[side];
if (0. > hit_z) {
for (int layer = layer_cnt; layer >= 0; --layer) {
if (layer < 1 || frags[layer-1].pt.z >= hit_z) {
// we're not as close to the screen as the fragment
// before the empty slot, so insert here
if (layer < LAYER_MAX) {
frags[layer] = sphere_shading(
sphere_list[id],
hit_depths[side] * dir,
dimming * color_list[id],
id
);
}
break;
} else {
// we're closer to the screen than the fragment before
// the empty slot, so move that fragment into the empty
// slot
frags[layer] = frags[layer-1];
}
}
layer_cnt = min(layer_cnt + 1, LAYER_MAX);
dimming = INTERIOR_DIMMING;
}
}
}
/* DEBUG */
// in debug mode, show the layer count instead of the shaded image
if (debug_mode) {
// at the bottom of the screen, show the color scale instead of the
// layer count
if (gl_FragCoord.y < 10.) layer_cnt = int(16. * gl_FragCoord.x / resolution.x);
// convert number to color
ivec3 bits = layer_cnt / ivec3(1, 2, 4);
vec3 color = mod(vec3(bits), 2.);
if (layer_cnt % 16 >= 8) {
color = mix(color, vec3(0.5), 0.5);
}
outColor = vec4(color, 1.);
return;
}
// highlight intersections and cusps
for (int i = layer_cnt-1; i >= 1; --i) {
// intersections
taggedFrag frag0 = frags[i];
taggedFrag frag1 = frags[i-1];
float ixn_sin = length(cross(frag0.normal, frag1.normal));
vec3 disp = frag0.pt - frag1.pt;
float ixn_dist = max(
abs(dot(frag1.normal, disp)),
abs(dot(frag0.normal, disp))
) / ixn_sin;
float ixn_highlight = 0.5 * highlight * (1. - smoothstep(2./3.*ixn_threshold, 1.5*ixn_threshold, ixn_dist));
frags[i].color = mix(frags[i].color, vec4(1.), ixn_highlight);
frags[i-1].color = mix(frags[i-1].color, vec4(1.), ixn_highlight);
// cusps
float cusp_cos = abs(dot(dir, frag0.normal));
float cusp_threshold = 2.*sqrt(ixn_threshold * sphere_list[frag0.id].lt.s);
float cusp_highlight = highlight * (1. - smoothstep(2./3.*cusp_threshold, 1.5*cusp_threshold, cusp_cos));
frags[i].color = mix(frags[i].color, vec4(1.), cusp_highlight);
}
// composite the sphere fragments
vec3 color = vec3(0.);
for (int i = layer_cnt-1; i >= layer_threshold; --i) {
if (frags[i].pt.z < 0.) {
vec4 frag_color = frags[i].color;
color = mix(color, frag_color.rgb, frag_color.a);
}
}
outColor = vec4(sRGB(color), 1.);
}

4
app-proto/sketch-outline/src/main.rs
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@ -29,14 +29,14 @@ fn main() {
Element {
id: String::from("wing_b"),
label: String::from("Wing B"),
color: [1.00_f32, 0.25_f32, 0.00_f32],
color: [0.00_f32, 0.25_f32, 1.00_f32],
rep: DVector::<f64>::from_column_slice(&[-0.5, -0.5, 0.0, 0.5, -0.25])
},
Element {
id: String::from("central"),
label: String::from("Central"),
color: [0.75_f32, 0.75_f32, 0.75_f32],
rep: DVector::<f64>::from_column_slice(&[0.0, 0.0, 0.0, 0.25, -1.0])
rep: DVector::<f64>::from_column_slice(&[0.0, 0.0, 0.0, 0.25, 1.0])
}
])
}