dyna3/app-proto/inversive-display/src/main.rs

// based on the WebGL example in the `wasm-bindgen` guide
//
//   https://rustwasm.github.io/wasm-bindgen/examples/webgl.html
//
// and this StackOverflow answer by wangdq
//
//   https://stackoverflow.com/a/39684775
//

extern crate js_sys;
use sycamore::{prelude::*, rt::{JsCast, JsValue}};
use web_sys::{console, WebGl2RenderingContext, WebGlShader};

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
}

// 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
    );
}

fn main() {
    // set up a config option that forwards panic messages to `console.error`
    #[cfg(feature = "console_error_panic_hook")]
    console_error_panic_hook::set_once();
    
    sycamore::render(|| {
        let ctrl_x = create_signal(0.0);
        let ctrl_y = create_signal(0.0);
        let radius_x = create_signal(1.0);
        let radius_y = create_signal(1.0);
        let opacity = create_signal(0.5);
        let highlight = create_signal(0.2);
        let layer_threshold = create_signal(0.0);
        let display = create_node_ref();
        
        on_mount(move || {
            // get the display canvas
            let canvas = display
                .get::<DomNode>()
                .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));
            
            // find indices of vertex attributes and uniforms
            let position_index = ctx.get_attrib_location(&program, "position") as u32;
            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 radius_loc = ctx.get_uniform_location(&program, "radius");
            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");
            
            // 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
            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));
                
                // pass the control parameters
                ctx.uniform2f(ctrl_loc.as_ref(), ctrl_x.get() as f32, ctrl_y.get() as f32);
                ctx.uniform2f(radius_loc.as_ref(), radius_x.get() as f32, radius_y.get() as f32);
                ctx.uniform1f(opacity_loc.as_ref(), opacity.get() as f32);
                ctx.uniform1f(highlight_loc.as_ref(), highlight.get() as f32);
                ctx.uniform1i(layer_threshold_loc.as_ref(), layer_threshold.get() as i32);
                
                // draw the scene
                ctx.draw_arrays(WebGl2RenderingContext::TRIANGLES, 0, VERTEX_CNT as i32);
            });
        });
        
        view! {
            div(id="app") {
                canvas(ref=display, width="600", height="600")
                input(
                    type="range",
                    min=-1.0,
                    max=1.0,
                    step=0.001,
                    bind:valueAsNumber=ctrl_x
                )
                input(
                    type="range",
                    min=-1.0,
                    max=1.0,
                    step=0.001,
                    bind:valueAsNumber=ctrl_y
                )
                input(
                    type="range",
                    min=0.5,
                    max=1.5,
                    step=0.001,
                    bind:valueAsNumber=radius_x
                )
                input(
                    type="range",
                    min=0.5,
                    max=1.5,
                    step=0.001,
                    bind:valueAsNumber=radius_y
                )
                input(
                    type="range",
                    max=1.0,
                    step=0.001,
                    bind:valueAsNumber=opacity
                )
                input(
                    type="range",
                    max=1.0,
                    step=0.001,
                    bind:valueAsNumber=highlight
                )
                input(
                    type="range",
                    max=3.0,
                    step=1.0,
                    bind:valueAsNumber=layer_threshold
                )
            }
        }
    });
}