root/test/opengl/sum_reduction.cpp

DEFINITIONS

1. main

#include "Halide.h"
#include <stdio.h>

#include "testing.h"

using namespace Halide;

int main() {
    // This test must be run with an OpenGL target.
    const Target target = get_jit_target_from_environment().with_feature(Target::OpenGL);

    // Define the input
    const int width = 10, height = 10, channels = 4;
    Buffer<float> input(width, height, channels);
    input.fill([](int x, int y, int c) {
        return float(x + y);
    });

    // Define the algorithm.
    Var x, y, c;
    RDom r(0, 5, "r");
    Func g;
    Expr coordx = clamp(x + r, 0, input.width() - 1);
    g(x, y, c) = cast<float>(sum(input(coordx, y, c)) / sum(r) * 255.0f);

    // Schedule f and g to compute in separate passes on the GPU.
    g.bound(c, 0, 4).glsl(x, y, c);

    // Generate the result.
    Buffer<float> result = g.realize(width, height, channels, target);
    result.copy_to_host();

    // Check the result.
    if (!Testing::check_result<float>(result, 1e-3, [&](int x, int y, int c) {
            float temp = 0.0f;
            for (int r = 0; r < 5; r++) {
                temp += input(std::min(x + r, input.width() - 1), y, c);
            }
            return temp / 10.0f * 255.0f;
        })) {
        return 1;
    }

    printf("Success!\n");
    return 0;
}