main.rs

use bevy::{prelude::*, render::{mesh::Indices, pipeline::{PipelineDescriptor, PrimitiveTopology, RenderPipeline}, shader::{ShaderStage, ShaderStages}}};

/// This example illustrates how to add a custom attribute to a mesh and use it in a custom shader.
fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_startup_system(setup)
        .run();
}

const VERTEX_SHADER: &str = r#"
#version 450
layout(location = 0) in vec3 Vertex_Position;

layout(set = 0, binding = 0) uniform CameraViewProj {
    mat4 ViewProj;
};
layout(set = 1, binding = 0) uniform Transform {
    mat4 Model;
};
void main() {
    gl_Position = ViewProj * Model * vec4(Vertex_Position, 1.0);
}
"#;

const FRAGMENT_SHADER: &str = r#"
#version 450
layout(location = 0) out vec4 o_Target;

void main() {
    o_Target = vec4(0.6, 0.4, 0.2, 1.0);
}
"#;

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut pipelines: ResMut<Assets<PipelineDescriptor>>,
    mut shaders: ResMut<Assets<Shader>>,
) {
    // Create a new shader pipeline
    let pipeline_handle = pipelines.add(PipelineDescriptor::default_config(ShaderStages {
        vertex: shaders.add(Shader::from_glsl(ShaderStage::Vertex, VERTEX_SHADER)),
        fragment: Some(shaders.add(Shader::from_glsl(ShaderStage::Fragment, FRAGMENT_SHADER))),
    }));

    let v_arr = vec![
        [-0.5, -0.5, -0.5],
        [0.5, -0.5, -0.5],
        [0.5, 0.5, -0.5],
        [-0.5, 0.5, -0.5],
    ];

    let v_f32 = vec![
        -0.5, -0.5, -0.5,
        0.5, -0.5, -0.5,
        0.5, 0.5, -0.5,
        -0.5, 0.5, -0.5,
    ];

    let indices = vec![0, 1, 2, 2, 3, 0];

    let mut mesh = Mesh::new(PrimitiveTopology::TriangleList);
    mesh.set_indices(Some(Indices::U32(indices)));
    mesh.set_attribute(Mesh::ATTRIBUTE_POSITION, v_f32); //Change from v_f32 to v_arr to render the plane

    // plane
    commands.spawn_bundle(MeshBundle {
        mesh: meshes.add(mesh),
        render_pipelines: RenderPipelines::from_pipelines(vec![RenderPipeline::new(
            pipeline_handle,
        )]),
        ..Default::default()
    });
    // camera
    commands.spawn_bundle(PerspectiveCameraBundle {
        transform: Transform::from_xyz(3.0, 5.0, 8.0).looking_at(Vec3::ZERO, Vec3::Y),
        ..Default::default()
    });
}