// Fragment stage of a tree drawn with `FloraMaterial` or `GrowthMaterial` (main pass, forward
// only): Bevy's `pbr.wesl` with the leaf's surface and the season's snow before lighting and the
// light through the leaf after it. Wood (no FLORA_LEAF) is StandardMaterial's, under the snow.
import bevy_pbr::{
render::{
pbr_functions::alpha_discard,
pbr_fragment::pbr_input_from_standard_material,
forward_io::{VertexOutput, FragmentOutput},
pbr_functions::{apply_pbr_lighting, main_pass_post_lighting_processing},
mesh_view_bindings::view,
},
decal::clustered::apply_decals,
};
@if(VISIBILITY_RANGE_DITHER)
import bevy_pbr::render::pbr_functions::visibility_range_dither;
@if(FLORA_DETAIL && !FLORA_LEAF)
import package::shading::common::bark_surface;
@if(FLORA_DETAIL && FLORA_LEAF)
import package::shading::common::leaf_detail;
@if(FLORA_TOON)
import package::shading::common::{toon_lighting, toon_rim};
@if(FLORA_LEAF)
import package::shading::common::{leaf_surface, leaf_transmission};
import package::shading::common::{snow_on, snow_shelter, facing_normal, LEAF_FROST};
@if(FLORA_SEE_THROUGH)
import package::shading::common::see_through;
@if(FLORA_FIRE && !FLORA_LEAF)
import package::shading::common::{fire_at, wood_char, char_wood, ember_flicker, ember_glow, EMBER, EMBER_NITS};
@if(FLORA_FIRE && !FLORA_LEAF)
import bevy_pbr::render::mesh_view_bindings::globals;
@if(FLORA_FIRE && FLORA_LEAF)
import package::shading::common::{scorch_leaf, LEAF_FLAME, LEAF_FLAME_NITS};
@fragment
fn fragment(
vertex_output: VertexOutput,
@builtin(front_facing) is_front: bool,
) -> FragmentOutput {
var in = vertex_output;
// In the crossfade section of a visibility range, discard according to the dither pattern.
@if(VISIBILITY_RANGE_DITHER)
visibility_range_dither(in.position, in.visibility_range_dither);
// A camera sees through the trees in front of what it follows (`SeeThroughTrees`).
@if(FLORA_SEE_THROUGH)
see_through(in.world_position.xyz, in.position.xy, view.world_position);
var pbr_input = pbr_input_from_standard_material(in, is_front);
pbr_input.material.base_color = alpha_discard(
pbr_input.material.flags,
pbr_input.material.alpha_cutoff,
pbr_input.material.base_color
);
@if(FLORA_DETAIL && !FLORA_LEAF)
bark_surface(&pbr_input, in.uv, in.uv_b.x);
// A flower (vertex alpha 0, `FoliageParams::blossom`) is a plain petal: no leaf scan, veins or
// leaf gloss.
@if(FLORA_LEAF && VERTEX_COLORS)
let flower = in.color.a < 0.5;
@if(FLORA_LEAF && !VERTEX_COLORS)
let flower = false;
@if(FLORA_DETAIL && FLORA_LEAF)
if !flower {
leaf_detail(&pbr_input, in.uv);
}
@if(FLORA_LEAF)
if !flower {
leaf_surface(&pbr_input, in.uv, in.uv_b);
}
// The fire (`FloraFire`): wood chars from the ground up as the fire where it stands chars, and
// its cracks glow while it burns; a leaf scorches brown and glows as it burns away (both from
// the vertex stage, in its colour's alpha).
var ember = vec3<f32>(0.0);
@if(FLORA_FIRE && !FLORA_LEAF) {
let fire = fire_at(in.world_position.xyz);
if fire.x > 0.0 {
var h = 0.0;
@if(VERTEX_UVS_B)
h = in.uv_b.y;
var uv = vec2<f32>(0.0);
@if(VERTEX_UVS_A)
uv = in.uv;
let charred = wood_char(fire.x, h);
let crack = char_wood(&pbr_input, charred, uv);
let flicker = ember_flicker(in.world_position.xyz, globals.time);
ember = EMBER * EMBER_NITS * ember_glow(fire.y) * charred * crack * flicker;
}
}
@if(FLORA_FIRE && FLORA_LEAF && VERTEX_COLORS) {
if !flower {
scorch_leaf(&pbr_input, saturate(in.color.a - 1.0));
ember = LEAF_FLAME * LEAF_FLAME_NITS * max(in.color.a - 2.0, 0.0);
}
}
// The season's snow (none in summer, which leaves the surface as it was): on the side of a leaf
// card the camera sees, if that side faces up, and a dusting on every leaf, as much as the leaf
// sees of the sky; on the wood, by its own normal. A leaf under snow lets no light through.
@if(FLORA_LEAF)
let snowed = snow_on(
&pbr_input,
facing_normal(pbr_input.world_position.xyz, pbr_input.V),
snow_shelter(in.uv_b.y),
LEAF_FROST,
);
@else
let snowed = snow_on(&pbr_input, pbr_input.world_normal, 1.0, 0.0);
apply_decals(&pbr_input);
var out: FragmentOutput;
@if(FLORA_TOON)
out.color = toon_lighting(pbr_input);
@else
out.color = apply_pbr_lighting(pbr_input);
@if(FLORA_LEAF)
out.color = vec4<f32>(
out.color.rgb + view.exposure * leaf_transmission(pbr_input, in.uv_b.y, flower) * (1.0 - snowed),
out.color.a
);
@if(FLORA_TOON)
out.color = vec4<f32>(out.color.rgb * toon_rim(pbr_input.world_normal, pbr_input.V), out.color.a);
// Embers and burning leaves give light of their own, after the toon rim, which would darken it.
@if(FLORA_FIRE)
out.color = vec4<f32>(out.color.rgb + view.exposure * ember, out.color.a);
out.color = main_pass_post_lighting_processing(pbr_input, out.color);
return out;
}