49 lines
2.0 KiB
WebGPU Shading Language
49 lines
2.0 KiB
WebGPU Shading Language
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#define_import_path bevy_core_pipeline::oit
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#import bevy_pbr::mesh_view_bindings::{view, oit_layers, oit_layer_ids, oit_settings}
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#ifdef OIT_ENABLED
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// Add the fragment to the oit buffer
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fn oit_draw(position: vec4f, color: vec4f) {
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// Don't add fully transparent fragments to the list
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// because we don't want to have to sort them in the resolve pass
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if color.a < oit_settings.alpha_threshold {
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return;
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}
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// get the index of the current fragment relative to the screen size
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let screen_index = i32(floor(position.x) + floor(position.y) * view.viewport.z);
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// get the size of the buffer.
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// It's always the size of the screen
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let buffer_size = i32(view.viewport.z * view.viewport.w);
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// gets the layer index of the current fragment
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var layer_id = atomicAdd(&oit_layer_ids[screen_index], 1);
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// exit early if we've reached the maximum amount of fragments per layer
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if layer_id >= oit_settings.layers_count {
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// force to store the oit_layers_count to make sure we don't
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// accidentally increase the index above the maximum value
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atomicStore(&oit_layer_ids[screen_index], oit_settings.layers_count);
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// TODO for tail blending we should return the color here
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return;
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}
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// get the layer_index from the screen
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let layer_index = screen_index + layer_id * buffer_size;
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let rgb9e5_color = bevy_pbr::rgb9e5::vec3_to_rgb9e5_(color.rgb);
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let depth_alpha = pack_24bit_depth_8bit_alpha(position.z, color.a);
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oit_layers[layer_index] = vec2(rgb9e5_color, depth_alpha);
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}
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#endif // OIT_ENABLED
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fn pack_24bit_depth_8bit_alpha(depth: f32, alpha: f32) -> u32 {
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let depth_bits = u32(saturate(depth) * f32(0xFFFFFFu) + 0.5);
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let alpha_bits = u32(saturate(alpha) * f32(0xFFu) + 0.5);
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return (depth_bits & 0xFFFFFFu) | ((alpha_bits & 0xFFu) << 24u);
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}
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fn unpack_24bit_depth_8bit_alpha(packed: u32) -> vec2<f32> {
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let depth_bits = packed & 0xFFFFFFu;
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let alpha_bits = (packed >> 24u) & 0xFFu;
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return vec2(f32(depth_bits) / f32(0xFFFFFFu), f32(alpha_bits) / f32(0xFFu));
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}
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