Application prototype #14
@ -73,6 +73,7 @@ fn main() {
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let ctrl_x = create_signal(0.0);
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let ctrl_y = create_signal(0.0);
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let opacity = create_signal(0.6);
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let layer_threshold = create_signal(0.0);
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let display = create_node_ref();
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on_mount(move || {
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@ -116,11 +117,14 @@ fn main() {
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// controls
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uniform vec2 ctrl;
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uniform float opacity;
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uniform int layer_threshold;
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// light and camera
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const float focal_slope = 0.3;
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const vec3 light_dir = normalize(vec3(2., 2., 1.));
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// --- inversive geometry ---
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struct vecInv {
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vec3 sp;
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vec2 lt;
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@ -136,7 +140,26 @@ fn main() {
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);
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}
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vec4 shade_sphere(vecInv v, vec3 pt) {
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// --- shading ---
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struct taggedFrag {
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vec4 color;
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float depth;
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};
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taggedFrag[2] sort(taggedFrag a, taggedFrag b) {
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taggedFrag[2] result;
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if (a.depth < b.depth) {
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result[0] = a;
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result[1] = b;
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} else {
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result[0] = b;
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result[1] = a;
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}
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return result;
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}
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taggedFrag sphere_shading(vecInv v, vec3 pt, vec3 base_color) {
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// the expression for normal needs to be checked. it's
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// supposed to give the negative gradient of the lorentz
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// product between the impact point vector and the sphere
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@ -147,20 +170,13 @@ fn main() {
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vec3 color;
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float incidence = dot(normal_front, light_dir);
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if (incidence < 0.) {
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color = mix(vec3(0.2, 0.0, 0.4), vec3(0.1, 0.0, 0.2), -incidence);
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} else {
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color = mix(vec3(0.4, 0.0, 0.2), vec3(1.0, 0.8, 1.0), incidence);
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}
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return vec4(color, opacity);
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float illum = mix(0.4, 1.0, max(incidence, 0.0));
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return taggedFrag(vec4(illum * base_color, opacity), -pt.z);
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}
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void main() {
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vec2 scr = (2.*gl_FragCoord.xy - resolution) / shortdim;
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vec3 dir = vec3(focal_slope * scr, -1.);
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vecInv v = sphere(vec3(ctrl, -5.), 1.);
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// --- ray-casting ---
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vec2 sphere_cast(vecInv v, vec3 dir) {
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float a = -v.lt.s * dot(dir, dir);
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float b = dot(v.sp, dir);
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float c = -v.lt.t;
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@ -168,18 +184,57 @@ fn main() {
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float scale = -b/(2.*a);
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float adjust = 4.*a*c/(b*b);
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vec3 color = vec3(0.);
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if (adjust < 1.) {
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float offset = sqrt(1. - adjust);
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float u_front = scale * (1. - offset);
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float u_back = scale * (1. + offset);
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if (u_back > 0.) {
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vec4 sphere_color = shade_sphere(v, u_back * dir);
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color = mix(color, sphere_color.rgb, sphere_color.a);
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}
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if (u_front > 0.) {
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vec4 sphere_color = shade_sphere(v, u_front * dir);
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color = mix(color, sphere_color.rgb, sphere_color.a);
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return vec2(
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scale * (1. - offset),
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scale * (1. + offset)
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);
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} else {
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// these parameters describe points behind the camera,
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// so the corresponding fragments won't be drawn
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return vec2(-1., -1.);
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}
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}
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void main() {
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vec2 scr = (2.*gl_FragCoord.xy - resolution) / shortdim;
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vec3 dir = vec3(focal_slope * scr, -1.);
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// initialize two spheres
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vecInv v0 = sphere(vec3(0.5, 0.5, -5. + ctrl.x), 1.);
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vecInv v1 = sphere(vec3(-0.5, -0.5, -5. + ctrl.y), 1.);
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vec3 color0 = vec3(1.0, 0.5, 0.0);
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vec3 color1 = vec3(0.0, 0.5, 1.0);
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// cast rays through the spheres
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vec2 u0 = sphere_cast(v0, dir);
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vec2 u1 = sphere_cast(v1, dir);
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// shade and depth-sort the impact points
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taggedFrag front_hits[2] = sort(
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sphere_shading(v0, u0[0] * dir, color0),
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sphere_shading(v1, u1[0] * dir, color1)
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);
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taggedFrag back_hits[2] = sort(
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sphere_shading(v0, u0[1] * dir, color0),
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sphere_shading(v1, u1[1] * dir, color1)
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);
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taggedFrag middle_frags[2] = sort(front_hits[1], back_hits[0]);
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// finish depth sorting
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taggedFrag frags_by_depth[4];
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frags_by_depth[0] = front_hits[0];
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frags_by_depth[1] = middle_frags[0];
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frags_by_depth[2] = middle_frags[1];
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frags_by_depth[3] = back_hits[1];
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// composite the sphere fragments
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vec3 color = vec3(0.);
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for (int i = 3; i >= layer_threshold; --i) {
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if (frags_by_depth[i].depth > 0.) {
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vec4 frag_color = frags_by_depth[i].color;
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color = mix(color, frag_color.rgb, frag_color.a);
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}
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}
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outColor = vec4(color, 1.);
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@ -208,6 +263,7 @@ fn main() {
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let shortdim_loc = ctx.get_uniform_location(&program, "shortdim");
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let ctrl_loc = ctx.get_uniform_location(&program, "ctrl");
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let opacity_loc = ctx.get_uniform_location(&program, "opacity");
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let layer_threshold_loc = ctx.get_uniform_location(&program, "layer_threshold");
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// create a vertex array and bind it to the graphics context
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let vertex_array = ctx.create_vertex_array().unwrap();
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@ -238,6 +294,7 @@ fn main() {
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// pass the control parameters
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ctx.uniform2f(ctrl_loc.as_ref(), ctrl_x.get() as f32, ctrl_y.get() as f32);
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ctx.uniform1f(opacity_loc.as_ref(), opacity.get() as f32);
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ctx.uniform1i(layer_threshold_loc.as_ref(), layer_threshold.get() as i32);
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// clear the screen and draw the scene
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ctx.clear_color(0.0, 0.0, 0.0, 1.0);
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@ -253,22 +310,28 @@ fn main() {
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type="range",
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min=-1.0,
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max=1.0,
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step=0.01,
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step=0.001,
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bind:valueAsNumber=ctrl_x
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)
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input(
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type="range",
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min=-1.0,
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max=1.0,
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step=0.01,
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step=0.001,
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bind:valueAsNumber=ctrl_y
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)
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input(
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type="range",
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max=1.0,
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step=0.01,
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step=0.001,
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bind:valueAsNumber=opacity
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)
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input(
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type="range",
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max=3.0,
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step=1.0,
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bind:valueAsNumber=layer_threshold
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)
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}
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}
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});
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