[rs] Change the texture sample type for the cube example from Float to Uint, and move the mandelbrot->color mapping functionality from the texel generation code to the fragment shader.

wgpu/examples/cube/main.rs

@@ -2,7 +2,7 @@
 mod framework;
 
 use bytemuck::{Pod, Zeroable};
-use std::{borrow::Cow, iter, mem};
+use std::{borrow::Cow, mem};
 use wgpu::util::DeviceExt;
 
 #[repr(C)]
@@ -67,7 +67,7 @@ fn create_vertices() -> (Vec<Vertex>, Vec<u16>) {
 
 fn create_texels(size: usize) -> Vec<u8> {
     (0..size * size)
-        .flat_map(|id| {
+        .map(|id| {
             // get high five for recognizing this ;)
             let cx = 3.0 * (id % size) as f32 / (size - 1) as f32 - 2.0;
             let cy = 2.0 * (id / size) as f32 / (size - 1) as f32 - 1.0;
@@ -78,10 +78,7 @@ fn create_texels(size: usize) -> Vec<u8> {
                 y = 2.0 * old_x * y + cy;
                 count += 1;
             }
-            iter::once(0xFF - (count * 5) as u8)
-                .chain(iter::once(0xFF - (count * 15) as u8))
-                .chain(iter::once(0xFF - (count * 50) as u8))
-                .chain(iter::once(0xFF))
+            count
         })
         .collect()
 }
@@ -155,20 +152,11 @@ impl framework::Example for Example {
                     visibility: wgpu::ShaderStage::FRAGMENT,
                     ty: wgpu::BindingType::Texture {
                         multisampled: false,
-                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
+                        sample_type: wgpu::TextureSampleType::Uint,
                         view_dimension: wgpu::TextureViewDimension::D2,
                     },
                     count: None,
                 },
-                wgpu::BindGroupLayoutEntry {
-                    binding: 2,
-                    visibility: wgpu::ShaderStage::FRAGMENT,
-                    ty: wgpu::BindingType::Sampler {
-                        comparison: false,
-                        filtering: true,
-                    },
-                    count: None,
-                },
             ],
         });
         let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
@@ -191,7 +179,7 @@ impl framework::Example for Example {
             mip_level_count: 1,
             sample_count: 1,
             dimension: wgpu::TextureDimension::D2,
-            format: wgpu::TextureFormat::Rgba8UnormSrgb,
+            format: wgpu::TextureFormat::R8Uint,
             usage: wgpu::TextureUsage::SAMPLED | wgpu::TextureUsage::COPY_DST,
         });
         let texture_view = texture.create_view(&wgpu::TextureViewDescriptor::default());
@@ -204,22 +192,13 @@ impl framework::Example for Example {
             &texels,
             wgpu::ImageDataLayout {
                 offset: 0,
-                bytes_per_row: Some(std::num::NonZeroU32::new(4 * size).unwrap()),
+                bytes_per_row: Some(std::num::NonZeroU32::new(size).unwrap()),
                 rows_per_image: None,
             },
             texture_extent,
         );
 
         // Create other resources
-        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
-            address_mode_u: wgpu::AddressMode::ClampToEdge,
-            address_mode_v: wgpu::AddressMode::ClampToEdge,
-            address_mode_w: wgpu::AddressMode::ClampToEdge,
-            mag_filter: wgpu::FilterMode::Nearest,
-            min_filter: wgpu::FilterMode::Linear,
-            mipmap_filter: wgpu::FilterMode::Nearest,
-            ..Default::default()
-        });
         let mx_total = Self::generate_matrix(sc_desc.width as f32 / sc_desc.height as f32);
         let mx_ref: &[f32; 16] = mx_total.as_ref();
         let uniform_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
@@ -240,10 +219,6 @@ impl framework::Example for Example {
                     binding: 1,
                     resource: wgpu::BindingResource::TextureView(&texture_view),
                 },
-                wgpu::BindGroupEntry {
-                    binding: 2,
-                    resource: wgpu::BindingResource::Sampler(&sampler),
-                },
             ],
             label: None,
         });

wgpu/examples/cube/shader.wgsl

@@ -22,13 +22,13 @@ fn vs_main(
 }
 
 [[group(0), binding(1)]]
-var r_color: texture_2d<f32>;
-[[group(0), binding(2)]]
-var r_sampler: sampler;
+var r_color: texture_2d<u32>;
 
 [[stage(fragment)]]
 fn fs_main(in: VertexOutput) -> [[location(0)]] vec4<f32> {
-    return textureSample(r_color, r_sampler, in.tex_coord);
+    let tex = textureLoad(r_color, vec2<i32>(in.tex_coord * 256.0), 0);
+    let v = f32(tex.x) / 255.0;
+    return vec4<f32>(1.0 - (v * 5.0), 1.0 - (v * 15.0), 1.0 - (v * 50.0), 1.0);
 }
 
 [[stage(fragment)]]