glfft.hpp

/* Copyright (C) 2015 Hans-Kristian Arntzen <maister@archlinux.us>
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#ifndef GLFFT_HPP__
#define GLFFT_HPP__

#include "glfft_interface.hpp"
#include "glfft_common.hpp"
#include "glfft_wisdom.hpp"
#include <vector>
#include <unordered_map>
#include <limits>

/// GLFFT doesn't try to preserve GL state in any way.
/// E.g. SHADER_STORAGE_BUFFER bindings, programs bound, texture bindings, etc.
/// Applications calling this library must expect that some GL state will be modified.
/// No rendering state associated with graphics will be modified.

namespace GLFFT
{

class FFT
{
    public:
        /// @brief Creates a full FFT.
        ///
        /// All buffer allocation done by GLFFT will be done in constructor.
        /// Will throw if invalid parameters are passed.
        ///
        /// @param context       The graphics context.
        /// @param Nx            Number of samples in horizontal dimension.
        /// @param Ny            Number of samples in vertical dimension.
        /// @param type          The transform type.
        /// @param direction     Forward, inverse or inverse with convolution.
        ///                      For real-to-complex and complex-to-real transforms, the
        ///                      transform type must match.
        /// @param input_target  GL object type of input target. For real-to-complex with texture as input, ImageReal is used.
        /// @param output_target GL object type of output target. For complex-to-real with texture as output, ImageReal is used.
        /// @param cache         A program cache for caching the GLFFT programs created.
        /// @param options       FFT options such as performance related parameters and types.
        /// @param wisdom        GLFFT wisdom which can override performance related options
        ///                      (options.performance is used as a fallback).
        FFT(Context *context, unsigned Nx, unsigned Ny,
                Type type, Direction direction, Target input_target, Target output_target,
                std::shared_ptr<ProgramCache> cache, const FFTOptions &options,
                const FFTWisdom &wisdom = FFTWisdom());

        /// @brief Creates a single stage FFT. Used mostly internally for benchmarking partial FFTs.
        ///
        /// All buffer allocation done by GLFFT will be done in constructor.
        /// Will throw if invalid parameters are passed.
        ///
        /// @param context       The graphics context.
        /// @param Nx            Number of samples in horizontal dimension.
        /// @param Ny            Number of samples in vertical dimension.
        /// @param radix         FFT radix to test.
        /// @param p             Accumulated p factor. If 1, "first pass" mode is tested, otherwise, generic FFT stages.
        /// @param mode          The transform mode.
        /// @param input_target  GL object type of input target. For real-to-complex with texture as input, ImageReal is used.
        /// @param output_target GL object type of output target. For complex-to-real with texture as output, ImageReal is used.
        /// @param cache         A program cache for caching the GLFFT programs created.
        /// @param options       FFT options such as performance related parameters and types.
        FFT(Context *context, unsigned Nx, unsigned Ny, unsigned radix, unsigned p,
                Mode mode, Target input_target, Target output_target,
                std::shared_ptr<ProgramCache> cache, const FFTOptions &options);

        /// @brief Process the FFT.
        ///
        /// The type of object passed here must match what FFT was initialized with.
        ///
        /// @param cmd       Command buffer for issuing dispatch commands.
        /// @param output    Output buffer or image.
        ///                  NOTE: For images, the texture must be using immutable storage, i.e. glTexStorage2D!
        /// @param input     Input buffer or texture.
        /// @param input_aux If using convolution transform type,
        ///                  the content of input and input_aux will be multiplied together.
        void process(CommandBuffer *cmd, Resource *output, Resource *input, Resource *input_aux = nullptr);

        /// @brief Run process() multiple times, timing the results.
        ///
        /// Mostly used internally by GLFFT wisdom, glfft_cli's bench, and so on.
        ///
        /// @param context                  The graphics context.
        /// @param output                   Output buffer or image.
        ///                                 NOTE: For images, the texture must be using immutable storage, i.e. glTexStorage2D!
        /// @param input                    Input buffer or texture.
        /// @param warmup_iterations        Number of iterations to run to "warm" up GL, ensures we don't hit
        ///                                 recompilations or similar when benching.
        /// @param iterations               Number of iterations to run the benchmark.
        ///                                 Each iteration will ensure timing with a glFinish() followed by timing.
        /// @param dispatches_per_iteration Number of calls to process() we should do per iteration.
        /// @param max_time                 The max time the benchmark should run. Will be checked after each iteration is complete.
        ///
        /// @returns Average GPU time per process() call.
        double bench(Context *context, Resource *output, Resource *input,
                unsigned warmup_iterations, unsigned iterations, unsigned dispatches_per_iteration,
                double max_time = std::numeric_limits<double>::max());

        /// @brief Returns cost for a process() call. Only used for debugging.
        double get_cost() const { return cost; }

        /// @brief Returns number of passes (glDispatchCompute) in a process() call.
        unsigned get_num_passes() const { return passes.size(); }

        /// @brief Returns Nx.
        unsigned get_dimension_x() const { return size_x; }
        /// @brief Returns Ny.
        unsigned get_dimension_y() const { return size_y; }

        /// @brief Sets offset and scale parameters for normalized texel coordinates when sampling textures.
        ///
        /// By default, these values are 0.5 / size (samples in the center of texel (0, 0)).
        /// Scale is 1.0 / size, so it steps one texel for each coordinate in the FFT transform.
        /// Setting this to something custom is useful to get downsampling with GL_LINEAR -> FFT transform
        /// without having to downsample the texture first, then FFT.
        void set_texture_offset_scale(float offset_x, float offset_y, float scale_x, float scale_y)
        {
            texture.offset_x = offset_x;
            texture.offset_y = offset_y;
            texture.scale_x = scale_x;
            texture.scale_y = scale_y;
        }

        /// @brief Set binding range for input.
        ///
        /// If input is an SSBO, set a custom binding range to be passed to glBindBufferRange.
        /// By default, the entire buffer is bound.
        void set_input_buffer_range(size_t offset, size_t size)
        {
            ssbo.input.offset = offset;
            ssbo.input.size = size;
        }

        /// @brief Set binding range for input_aux.
        ///
        /// If input_aux is an SSBO, set a custom binding range to be passed to glBindBufferRange.
        /// By default, the entire buffer is bound.
        void set_input_aux_buffer_range(size_t offset, size_t size)
        {
            ssbo.input_aux.offset = offset;
            ssbo.input_aux.size = size;
        }

        /// @brief Set binding range for output.
        ///
        /// If output buffer is an SSBO, set a custom binding range to be passed to glBindBufferRange.
        /// By default, the entire buffer is bound.
        void set_output_buffer_range(size_t offset, size_t size)
        {
            ssbo.output.offset = offset;
            ssbo.output.size = size;
        }

        /// @brief Set samplers for input textures.
        ///
        /// Set sampler objects to be used for input and input_aux if textures are used as input.
        /// By default, sampler object 0 will be used (inheriting sampler parameters from the texture object itself).
        void set_samplers(Sampler *sampler0, Sampler *sampler1 = nullptr)
        {
            texture.samplers[0] = sampler0;
            texture.samplers[1] = sampler1;
        }

    private:
        Context *context;

        struct Pass
        {
            Parameters parameters;

            unsigned workgroups_x;
            unsigned workgroups_y;
            unsigned uv_scale_x;
            unsigned stride;
            Program *program;
        };

        double cost = 0.0;

        std::unique_ptr<Buffer> temp_buffer;
        std::unique_ptr<Buffer> temp_buffer_image;
        std::vector<Pass> passes;
        std::shared_ptr<ProgramCache> cache;

        std::unique_ptr<Program> build_program(const Parameters &params);
        static std::string load_shader_string(const char *path);
        static void store_shader_string(const char *path, const std::string &source);

        Program* get_program(const Parameters &params);

        struct
        {
            float offset_x = 0.0f, offset_y = 0.0f, scale_x = 1.0f, scale_y = 1.0f;
            Sampler *samplers[2] = { nullptr, nullptr };
        } texture;

        struct
        {
            struct
            {
                size_t offset = 0;
                size_t size = 0;
            } input, input_aux, output;
        } ssbo;
        unsigned size_x, size_y;
};

}

#endif