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use std::collections::HashMap;
use bytemuck::{Pod, Zeroable};
use wgpu::util::DeviceExt;
use crate::{GpuError, context::GpuContext};
pub struct ApplyEffectsOptions<'a> {
pub source: &'a wgpu::Texture,
pub width: u32,
pub height: u32,
pub passes: &'a [EffectPass],
}
#[derive(Clone, Debug)]
pub struct EffectPass {
pub shader: String,
pub uniforms: HashMap<String, UniformValue>,
}
#[derive(Clone, Debug)]
pub enum UniformValue {
Number(f32),
Vector(Vec<f32>),
}
#[repr(C)]
#[derive(Clone, Copy, Pod, Zeroable)]
struct EffectUniformBuffer {
resolution: [f32; 2],
direction: [f32; 2],
scalars: [f32; 4],
}
pub fn apply_effects(
context: &GpuContext,
ApplyEffectsOptions {
source,
width,
height,
passes,
}: ApplyEffectsOptions<'_>,
) -> Result<wgpu::Texture, GpuError> {
let mut current_texture: Option<wgpu::Texture> = None;
for pass in passes {
let input_texture = current_texture.as_ref().unwrap_or(source);
let output_texture =
context.create_render_texture(width, height, "gpu-effect-pass-output");
let input_view = input_texture.create_view(&wgpu::TextureViewDescriptor::default());
let output_view = output_texture.create_view(&wgpu::TextureViewDescriptor::default());
let texture_bind_group = context
.device()
.create_bind_group(&wgpu::BindGroupDescriptor {
label: Some("gpu-effect-texture-bind-group"),
layout: context
.shader_registry()
.effect_texture_bind_group_layout(),
entries: &[
wgpu::BindGroupEntry {
binding: 0,
resource: wgpu::BindingResource::TextureView(&input_view),
},
wgpu::BindGroupEntry {
binding: 1,
resource: wgpu::BindingResource::Sampler(context.linear_sampler()),
},
],
});
let uniform_buffer = context
.device()
.create_buffer_init(&wgpu::util::BufferInitDescriptor {
label: Some("gpu-effect-uniform-buffer"),
contents: bytemuck::bytes_of(&pack_effect_uniforms(pass, width, height)?),
usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
});
let uniform_bind_group = context
.device()
.create_bind_group(&wgpu::BindGroupDescriptor {
label: Some("gpu-effect-uniform-bind-group"),
layout: context
.shader_registry()
.effect_uniform_bind_group_layout(),
entries: &[wgpu::BindGroupEntry {
binding: 0,
resource: uniform_buffer.as_entire_binding(),
}],
});
let pipeline = context.shader_registry().get_effect_pipeline(&pass.shader)?;
let mut encoder = context
.device()
.create_command_encoder(&wgpu::CommandEncoderDescriptor {
label: Some("gpu-effect-command-encoder"),
});
{
let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
label: Some("gpu-effect-render-pass"),
color_attachments: &[Some(wgpu::RenderPassColorAttachment {
view: &output_view,
resolve_target: None,
depth_slice: None,
ops: wgpu::Operations {
load: wgpu::LoadOp::Clear(wgpu::Color::TRANSPARENT),
store: wgpu::StoreOp::Store,
},
})],
depth_stencil_attachment: None,
occlusion_query_set: None,
timestamp_writes: None,
multiview_mask: None,
});
render_pass.set_pipeline(pipeline);
render_pass.set_vertex_buffer(0, context.fullscreen_quad().slice(..));
render_pass.set_bind_group(0, &texture_bind_group, &[]);
render_pass.set_bind_group(1, &uniform_bind_group, &[]);
render_pass.draw(0..6, 0..1);
}
context.queue().submit([encoder.finish()]);
current_texture = Some(output_texture);
}
current_texture.ok_or_else(|| GpuError::UnknownEffectShader {
shader: "missing-effect-pass".to_string(),
})
}
fn pack_effect_uniforms(
pass: &EffectPass,
width: u32,
height: u32,
) -> Result<EffectUniformBuffer, GpuError> {
let shader = pass.shader.as_str();
let sigma = read_number_uniform(pass, "u_sigma")?;
let step = read_number_uniform(pass, "u_step")?;
let direction = read_vec2_uniform(pass, "u_direction")?;
for uniform in pass.uniforms.keys() {
if uniform == "u_sigma" || uniform == "u_step" || uniform == "u_direction" {
continue;
}
return Err(GpuError::UnsupportedUniform {
shader: shader.to_string(),
uniform: uniform.clone(),
});
}
Ok(EffectUniformBuffer {
resolution: [width as f32, height as f32],
direction,
scalars: [sigma, step, 0.0, 0.0],
})
}
fn read_number_uniform(pass: &EffectPass, uniform: &str) -> Result<f32, GpuError> {
let Some(value) = pass.uniforms.get(uniform) else {
return Err(GpuError::MissingUniform {
shader: pass.shader.clone(),
uniform: uniform.to_string(),
});
};
match value {
UniformValue::Number(value) => Ok(*value),
UniformValue::Vector(_) => Err(GpuError::InvalidNumberUniform {
shader: pass.shader.clone(),
uniform: uniform.to_string(),
}),
}
}
fn read_vec2_uniform(pass: &EffectPass, uniform: &str) -> Result<[f32; 2], GpuError> {
let Some(value) = pass.uniforms.get(uniform) else {
return Err(GpuError::MissingUniform {
shader: pass.shader.clone(),
uniform: uniform.to_string(),
});
};
let UniformValue::Vector(values) = value else {
return Err(GpuError::InvalidVectorUniform {
shader: pass.shader.clone(),
uniform: uniform.to_string(),
expected_length: 2,
});
};
if values.len() != 2 {
return Err(GpuError::InvalidVectorUniform {
shader: pass.shader.clone(),
uniform: uniform.to_string(),
expected_length: 2,
});
}
Ok([values[0], values[1]])
}
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