renderer_stencil.rs

use notan::prelude::*;

const VERT: ShaderSource = notan::vertex_shader! {
    r#"
    #version 450
    layout(location = 0) in vec2 a_pos;
    layout(location = 1) in vec3 a_color;

    layout(location = 0) out vec3 v_color;

    void main() {
        v_color = a_color;
        gl_Position = vec4(a_pos - 0.5, 0.0, 1.0);
    }
    "#
};

const FRAG: ShaderSource = notan::fragment_shader! {
    r#"
    #version 450
    precision mediump float;

    layout(location = 0) in vec3 v_color;
    layout(location = 0) out vec4 color;

    void main() {
        color = vec4(v_color, 1.0);
    }
    "#
};

#[derive(AppState)]
struct State {
    clear_options: ClearOptions,
    mask_pipeline: Pipeline,
    pipeline: Pipeline,
    mask_vbo: Buffer,
    vbo: Buffer,
}

#[notan_main]
fn main() -> Result<(), String> {
    notan::init_with(setup).draw(draw).build()
}

fn setup(gfx: &mut Graphics) -> State {
    let clear_options = ClearOptions {
        color: Some(Color::new(0.1, 0.2, 0.3, 1.0)),
        depth: None,
        stencil: Some(0),
    };

    let vertex_info = VertexInfo::new()
        .attr(0, VertexFormat::Float32x2)
        .attr(1, VertexFormat::Float32x3);

    let stencil_maks_opts = StencilOptions {
        stencil_fail: StencilAction::Keep,
        depth_fail: StencilAction::Keep,
        pass: StencilAction::Replace,
        compare: CompareMode::Always,
        read_mask: 0xff,
        write_mask: 0xff,
        reference: 1,
    };

    let mask_pipeline = gfx
        .create_pipeline()
        .from(&VERT, &FRAG)
        .with_vertex_info(&vertex_info)
        .with_stencil(stencil_maks_opts)
        .build()
        .unwrap();

    let stencil_opts = StencilOptions {
        stencil_fail: StencilAction::Keep,
        depth_fail: StencilAction::Keep,
        pass: StencilAction::Keep,
        compare: CompareMode::Equal,
        read_mask: 0xff,
        write_mask: 0x00,
        reference: 1,
    };

    let pipeline = gfx
        .create_pipeline()
        .from(&VERT, &FRAG)
        .with_vertex_info(&vertex_info)
        .with_stencil(stencil_opts)
        .build()
        .unwrap();

    // masking vertices
    #[rustfmt::skip]
    let mask_vertices = [
        0.5, 1.35, 1.0, 1.0, 1.0,
        0.25, 0.85, 1.0, 1.0, 1.0,
        0.75, 0.85, 1.0, 1.0, 1.0,

        0.75, 0.85, 1.0, 1.0, 1.0,
        0.5, 0.35, 1.0, 1.0, 1.0,
        1.0, 0.35, 1.0, 1.0, 1.0,

        0.25, 0.85, 1.0, 1.0, 1.0,
        0.0, 0.35, 1.0, 1.0, 1.0,
        0.5, 0.35, 1.0, 1.0, 1.0,

        0.5, 0.35, 1.0, 1.0, 1.0,
        0.25, -0.15, 1.0, 1.0, 1.0,
        0.75, -0.15, 1.0, 1.0, 1.0,

        1.0, 0.35, 1.0, 1.0, 1.0,
        0.75, -0.15, 1.0, 1.0, 1.0,
        1.25, -0.15, 1.0, 1.0, 1.0,

        0.0, 0.35, 1.0, 1.0, 1.0,
        -0.25, -0.15, 1.0, 1.0, 1.0,
        0.25, -0.15, 1.0, 1.0, 1.0,
    ];

    let mask_vbo = gfx
        .create_vertex_buffer()
        .with_info(&vertex_info)
        .with_data(&mask_vertices)
        .build()
        .unwrap();

    // triangle
    #[rustfmt::skip]
    let vertices = [
        0.5, 1.0, 1.0, 0.2, 0.3,
        0.0, 0.0, 0.1, 1.0, 0.3,
        1.0, 0.0, 0.1, 0.2, 1.0,
    ];

    let vbo = gfx
        .create_vertex_buffer()
        .with_info(&vertex_info)
        .with_data(&vertices)
        .build()
        .unwrap();

    State {
        clear_options,
        mask_pipeline: mask_pipeline,
        pipeline: pipeline,
        mask_vbo: mask_vbo,
        vbo: vbo,
    }
}

fn draw(gfx: &mut Graphics, state: &mut State) {
    let mut renderer = gfx.create_renderer();

    renderer.begin(Some(state.clear_options));

    // Render the mask
    renderer.set_pipeline(&state.mask_pipeline);
    renderer.bind_buffer(&state.mask_vbo);
    renderer.draw(0, 18);

    renderer.end();

    // render the triangle
    renderer.begin(None);
    renderer.set_pipeline(&state.pipeline);
    renderer.bind_buffer(&state.vbo);
    renderer.draw(0, 3);

    renderer.end();

    gfx.render(&renderer);
}