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refactor projections into their own module

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This commit is contained in:
Hartmut Seichter 2022-12-09 21:30:47 +01:00
parent 4e59d730fc
commit a7e92ba70a
6 changed files with 124 additions and 174 deletions
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2
src/main.rs
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@ -9,6 +9,7 @@ use crate::scene::*;
use crate::utils::*;
use crate::viewer::*;
use bevy::{prelude::*, window::PresentMode, render::camera::CameraProjectionPlugin};
use offaxis::{offaxis_camera_setup, OffAxisProjection};
@ -17,6 +18,7 @@ mod scene;
mod screeninfo;
mod utils;
mod viewer;
mod projection;
fn main() {
App::new()

100
src/offaxis.rs
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@ -7,6 +7,7 @@ use bevy::math::Mat4;
use crate::screeninfo::ScreenInfo;
use crate::viewer::*;
use crate::projection::*;
#[derive(Component, Debug, Clone, Reflect)]
#[reflect(Component, Default)]
@ -16,66 +17,10 @@ pub struct OffAxisProjection {
aspect: f32,
}
pub fn make_projection_rh_from_frustum(left: f32, right: f32, bottom: f32, top: f32, near:f32, far:f32) -> Mat4
{
// based on OpenSceneGraph / glFrustum implementation
let a = (right + left) / (right - left);
let b: f32 = (top + bottom) / (top - bottom);
let c= if far.abs() > f32::MAX { -1.0 } else { -(far + near) / (far - near)};
let d = if far.abs() > f32::MAX { -2.0 * near } else { -2.0 * far * near / (far - near) };
Mat4::from_cols(
Vec4::new(2.0 * near/(right-left),0.0,0.0,0.0),
Vec4::new(0.0,2.0*near/(top-bottom), 0.0,0.0),
Vec4::new(a, b, c, -1.0),
Vec4::new(0.0, 0.0, d, 0.0))
}
pub fn make_projection_rh_from_frustum_reversed(left: f32, right: f32, bottom: f32, top: f32, near:f32, far:f32) -> Mat4
{
assert!(near > 0.0);
//
// reversed z 0..1 projection based on https://thxforthefish.com/posts/reverse_z/
//
let a = (right + left) / (right - left);
let b: f32 = (top + bottom) / (top - bottom);
// let c= if far.abs() > f32::MAX { -1.0 } else { -(far + near) / (far - near)};
// let d = if far.abs() > f32::MAX { -2.0 * near } else { -2.0 * far * near / (far - near) };
let c = near / (far - near);
let d = far * near / (far - near);
Mat4::from_cols(
Vec4::new(2.0 * near/(right-left),0.0,0.0,0.0),
Vec4::new(0.0,2.0*near/(top-bottom), 0.0,0.0),
Vec4::new(a, b, c, -1.0),
Vec4::new(0.0, 0.0, d, 0.0))
}
pub fn make_projection_rh_custom(fov_y: f32, aspect_ratio: f32, z_near: f32, z_far: f32) -> Mat4
{
let tan_fovy = (fov_y * 0.5).tan(); // use half angle beta
let right = tan_fovy * aspect_ratio * z_near;
let left = -right;
let top = tan_fovy * z_near;
let bottom = -top;
//make_projection_rh_from_frustum(left, right, bottom, top, z_near, z_far)
make_projection_rh_from_frustum_reversed(left, right, bottom, top, z_near, z_far)
}
impl CameraProjection for OffAxisProjection {
fn get_projection_matrix(&self) -> Mat4 {
make_projection_rh_custom(45.0_f32.to_radians(), self.aspect, self.near, self.far)
// Mat4::perspective_rh(45.0_f32.to_radians(),
@ -101,7 +46,7 @@ impl Default for OffAxisProjection {
Self {
near: 0.1,
far: 1000.0,
aspect: 1.0,
aspect: 1.5,
}
}
}
@ -141,42 +86,3 @@ pub fn offaxis_camera_setup(mut commands: Commands) {
}
#[cfg(test)]
mod tests {
use bevy::prelude::Mat4;
use super::make_projection_rh_from_frustum;
#[test]
fn compare_projections() {
// build an on-axis frustum
let fovy = 33.0_f32;
let aspect_ratio = 1.6666_f32;
let z_near = 1.0_f32;
let z_far = 500.0_f32;
let tan_fovy = (fovy * 0.5).to_radians().tan(); // use half angle beta
let right = tan_fovy * aspect_ratio * z_near;
let left = -right;
let top = tan_fovy * z_near;
let bottom = -top;
let mat_frust = make_projection_rh_from_frustum(left, right, bottom, top, z_near, z_far);
println!("mat 1 {:?}",mat_frust);
let mat_pers = Mat4::perspective_rh_gl(fovy.to_radians(),aspect_ratio,z_near,z_far);
println!("mat 2 {:?}",mat_pers);
assert!(mat_frust.abs_diff_eq(mat_pers, f32::EPSILON));
}
}

94
src/projection.rs Normal file
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@ -0,0 +1,94 @@
use bevy::prelude::*;
use bevy::math::Mat4;
/// creates a conventional projection matrix from frustum planes
///
/// returns a potentially off-axis projection matrix
pub fn make_projection_rh_from_frustum(left: f32, right: f32, bottom: f32, top: f32, near:f32, far:f32) -> Mat4
{
// based on OpenSceneGraph / glFrustum implementation
let a = (right + left) / (right - left);
let b: f32 = (top + bottom) / (top - bottom);
let c= if far.abs() > f32::MAX { -1.0 } else { -(far + near) / (far - near)};
let d = if far.abs() > f32::MAX { -2.0 * near } else { -2.0 * far * near / (far - near) };
Mat4::from_cols(
Vec4::new(2.0 * near / (right-left),0.0,0.0,0.0),
Vec4::new(0.0, 2.0 *near / (top-bottom), 0.0,0.0),
Vec4::new(a, b, c, -1.0),
Vec4::new(0.0, 0.0, d, 0.0))
}
/// creates a projection from a frustum planes with a reversed depth mapped to [0..1]
pub fn make_projection_rh_from_frustum_reversed(left: f32, right: f32, bottom: f32, top: f32, z_near:f32, z_far:f32) -> Mat4
{
assert!(z_near > 0.0 && z_far > 0.0);
//
// reversed z 0..1 projection based on https://thxforthefish.com/posts/reverse_z/
//
let a = (right + left) / (right - left);
let b: f32 = (top + bottom) / (top - bottom);
let c = z_near / (z_far - z_near);
let d = z_far * z_near / (z_far - z_near);
Mat4::from_cols(
Vec4::new(2.0 * z_near / (right-left),0.0,0.0,0.0),
Vec4::new(0.0, 2.0 * z_near / (top-bottom), 0.0,0.0),
Vec4::new(a, b, c, -1.0),
Vec4::new(0.0, 0.0, d, 0.0))
}
pub fn make_projection_rh_custom(fov_y: f32, aspect_ratio: f32, z_near: f32, z_far: f32) -> Mat4
{
let tan_fovy = (fov_y * 0.5).tan(); // use half angle beta
let right = tan_fovy * aspect_ratio * z_near;
let left = -right;
let top = tan_fovy * z_near;
let bottom = -top;
//make_projection_rh_from_frustum(left, right, bottom, top, z_near, z_far)
make_projection_rh_from_frustum_reversed(left, right, bottom, top, z_near, z_far)
}
#[cfg(test)]
mod tests {
use bevy::prelude::Mat4;
use super::make_projection_rh_from_frustum;
#[test]
fn compare_projections() {
// build an on-axis frustum
let fovy = 33.0_f32;
let aspect_ratio = 1.6666_f32;
let z_near = 1.0_f32;
let z_far = 1000.0_f32;
let tan_fovy = (fovy * 0.5).to_radians().tan(); // use half angle beta
let right = tan_fovy * aspect_ratio * z_near;
let left = -right;
let top = tan_fovy * z_near;
let bottom = -top;
let mat_frust = make_projection_rh_from_frustum(left, right, bottom, top, z_near, z_far);
println!("mat 1 {:?}",mat_frust);
let mat_pers = Mat4::perspective_rh_gl(fovy.to_radians(),aspect_ratio,z_near,z_far);
println!("mat 2 {:?}",mat_pers);
assert!(mat_frust.abs_diff_eq(mat_pers, f32::EPSILON));
}
}

76
src/scene.rs
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@ -33,7 +33,6 @@ fn generalized_projection_stereo(eyePos : Vec3)
}
fn generalized_projection (
projectionScreen: ProjectionScreen,
eyePos: Vec3,
@ -100,77 +99,4 @@ pub fn build_scene(
..default()
});
// camera
// let mut cam = Camera3dBundle {
// transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
// ..default()
// };
// commands.spawn(cam);
// commands.spawn((Person, Position { x: 10.0, y: 10.0 }));
// commands.spawn()
// .insert(Person)
// .insert(Position { x: 10.0, y: 10.0 } );
// camera
// commands.spawn_bundle(OffAxisProjection {
// transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
// ..default()
// });
}
// pub fn modify_frustum(mut query: Query<&Frustum>)
// {
// let mut rng = rand::thread_rng();
// for mut q in query.iter() {
// for mut p in q.planes {
// println!("{:?}",p);
// let mut n = p.normal_d();
// n.w += rng.gen::<f32>();
// p = Plane::new(n);
// println!("{:?}",p);
// // p.normal_d() += rng.gen();
// }
// // println!("{:?}",q.frustum.planes.len());
// }
// }
// pub fn modify_projection(mut query: Query<&Projection>)
// {
// let mut rng = rand::thread_rng();
// for mut q in query.iter() {
// print!("{:?}",q);
// }
// }
// pub fn print_positions(query: Query<&Position>) {
// for _position in query.iter() {
// _ = 33;
// // println!("position {:?} {:?}", position.x, position.y)
// }
// }
// Problem with off-axis
// projection 2401, 240
}

15
src/screeninfo.rs
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@ -1,5 +1,5 @@
use bevy::{prelude::*, math::bool, render::primitives::Frustum};
use bevy::{prelude::*, math::bool, prelude::shape::Quad };
use rand::prelude::*;
use bevy::render::primitives::Plane;
@ -44,6 +44,19 @@ impl ScreenInfo {
}
}
pub fn build_debug_geometry(&self,
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
)
{
// plane
commands.spawn(PbrBundle {
mesh: meshes.add(Mesh::from( Quad { size: Vec2 { x: self.width, y: self.height }, flip:false })),
material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
..default()
});
}
pub fn update(&mut self) -> &mut Self {

11
src/viewer.rs
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@ -1,4 +1,6 @@
use bevy::{prelude::*, window::PresentMode, render::camera::CameraProjectionPlugin};
use crate::screeninfo::ScreenInfo;
// use offaxis::{offaxis_camera_setup, OffAxisProjection};
@ -36,10 +38,17 @@ pub fn simulate_viewer(mut query: Query<&mut Viewer>)
//v.position += Vec3::Y * 0.005;
v.alpha += 0.01;
let radius = 1.5;
v.position = Vec3::new(v.alpha.sin()*radius,v.alpha.cos()*radius + 1.0_f32,15.0);
let z_distance = 8.0_f32;
v.position = Vec3::new(v.alpha.sin()*radius,v.alpha.cos()*radius + 1.0_f32,z_distance);
let vm = Mat4::look_at_rh(v.position, Vec3::ZERO, Vec3::Y);
println!("{:?}",vm);
// view matrices should be orientation only