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shaders/16bit_arithmetic/compute_buffer_fp16_fallback.comp
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| #version 450 | ||
| /* Copyright (c) 2020-2024, Arm Limited and Contributors | ||
| * | ||
| * SPDX-License-Identifier: Apache-2.0 | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 the "License"; | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
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| // Allows us to use float16_t for arithmetic purposes. | ||
| #extension GL_EXT_shader_explicit_arithmetic_types_float16 : require | ||
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| // Allows us to use int16_t, uint16_t and float16_t for buffers. | ||
| #extension GL_EXT_shader_16bit_storage : require | ||
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| layout(local_size_x = 8, local_size_y = 8) in; | ||
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| layout(constant_id = 0) const uint WIDTH = 1; | ||
| layout(constant_id = 1) const uint HEIGHT = 1; | ||
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| layout(set = 0, binding = 0) readonly buffer SSBO | ||
| { | ||
| // It is possible to use native 16-bit types in SSBOs and UBOs. We could use uvec2 here and unpack manually. | ||
| // The key feature of 16-bit storage is to allow scalar access to 16-bit values however. | ||
| // Avoiding extra unpacking and packing can also be useful. | ||
| f16vec4 blob_data[]; | ||
| }; | ||
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| layout(rgba16f, set = 0, binding = 1) writeonly uniform mediump image2D o_results; | ||
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| layout(push_constant) uniform Registers | ||
| { | ||
| // Fallback for implementations which do not support PushConstant16. | ||
| uint num_blobs; | ||
| float seed; | ||
| ivec2 range; | ||
| } | ||
| registers; | ||
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| // This is very arbitrary. Expends a ton of arithmetic to compute | ||
| // something that looks similar to a lens flare. | ||
| f16vec4 compute_blob(f16vec2 pos, f16vec4 blob, float16_t seed) | ||
| { | ||
| f16vec2 offset = pos - blob.xy; | ||
| f16vec4 rg_offset = offset.xxyy * f16vec4(0.95hf, 1.0hf, 0.95hf, 1.0hf); | ||
| f16vec4 bs_offset = offset.xxyy * f16vec4(1.05hf, 1.1hf + seed, 1.05hf, 1.1hf + seed); | ||
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| f16vec4 rg_dot = rg_offset * rg_offset; | ||
| f16vec4 bs_dot = bs_offset * bs_offset; | ||
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| // Dot products can be somewhat awkward in FP16, since the result is a scalar 16-bit value, and we don't want that. | ||
| // To that end, we compute at least two dot products side by side, and rg_offset and bs_offset are swizzled | ||
| // such that we avoid swizzling across a 32-bit boundary. | ||
| f16vec4 dots = f16vec4(rg_dot.xy + rg_dot.zw, bs_dot.xy + bs_dot.zw) * blob.w; | ||
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| // Now we have square distances to blob center. | ||
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| // Gotta have some FMAs, right? :D | ||
| dots = dots * dots + dots; | ||
| dots = dots * dots + dots; | ||
| dots = dots * dots + dots; | ||
| dots = dots * dots + dots; | ||
| dots = dots * dots + dots; | ||
| dots = dots * dots + dots; | ||
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| f16vec4 parabolas = max(f16vec4(1.0hf, 1.0hf, 1.0hf, 0.9hf) - dots, f16vec4(0.0hf)); | ||
| parabolas -= parabolas.w; | ||
| parabolas = max(parabolas, f16vec4(0.0hf)); | ||
| return parabolas; | ||
| } | ||
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| void main() | ||
| { | ||
| uint num_blobs = uint(registers.num_blobs); | ||
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| float x = float(gl_GlobalInvocationID.x) / float(WIDTH) - 0.5; | ||
| float y = float(gl_GlobalInvocationID.y) / float(HEIGHT) - 0.5; | ||
| f16vec2 pos = f16vec2(x, y); | ||
| f16vec4 result = f16vec4(0.0hf); | ||
| float16_t seed = float16_t(registers.seed); | ||
| ivec2 range = ivec2(registers.range); | ||
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| const float16_t EXPAND_FACTOR = 0.3hf; | ||
| float16_t stride = seed * EXPAND_FACTOR; | ||
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| for (uint i = 0; i < num_blobs; i++) | ||
| { | ||
| f16vec4 blob = blob_data[i]; | ||
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| // Get as much mileage out of the buffer load as possible. | ||
| for (int y = -range.y; y <= range.y; y++) | ||
| for (int x = -range.x; x <= range.x; x++) | ||
| result += compute_blob(pos + stride * f16vec2(x, y), blob, seed); | ||
| } | ||
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| imageStore(o_results, ivec2(gl_GlobalInvocationID.xy), result); | ||
| } |