/*******************************************************
 * Copyright (c) 2015-2019, ArrayFire
 * All rights reserved.
 *
 * This file is distributed under 3-clause BSD license.
 * The complete license agreement can be obtained at:
 * http://arrayfire.com/licenses/BSD-3-Clause
 ********************************************************/

#include <forge.h>
#include <cuda_runtime.h>
#define USE_FORGE_CUDA_COPY_HELPERS
#include <ComputeCopy.h>

#define PI 3.14159265359

const unsigned DIMX = 640;
const unsigned DIMY = 480;
const float MINIMUM = 1.0f;
const float MAXIMUM = 20.f;
const float STEP    = 2.0f;
const float NELEMS  = (MAXIMUM-MINIMUM+1)/STEP;
const unsigned DPOINTS[] = {5, 5, 5, 15, 15, 5, 15, 15};

void generatePoints(float* points, float* dirs);

inline int divup(int a, int b)
{
    return (a+b-1)/b;
}

int main(void)
{
    unsigned* dpoints;
    float* points;
    float* dirs;
    /*
     * First Forge call should be a window creation call
     * so that necessary OpenGL context is created for any
     * other forge::* object to be created successfully
     */
    forge::Window wnd(DIMX, DIMY, "Vector Field Demo");
    wnd.makeCurrent();

    forge::Chart chart(FG_CHART_2D);
    chart.setAxesLimits(MINIMUM-1.0f, MAXIMUM, MINIMUM-1.0f, MAXIMUM);
    chart.setAxesTitles("x-axis", "y-axis");

    forge::Plot divPoints = chart.plot(4, forge::u32, FG_PLOT_SCATTER, FG_MARKER_CIRCLE);
    divPoints.setColor(0.9f, 0.9f, 0.0f, 1.f);
    divPoints.setLegend("Convergence Points");
    divPoints.setMarkerSize(24);

    size_t npoints = NELEMS*NELEMS;

    forge::VectorField field = chart.vectorField(npoints, forge::f32);
    field.setColor(0.f, 0.6f, 0.3f, 1.f);

    FORGE_CUDA_CHECK(cudaMalloc((void**)&dpoints, 8*sizeof(unsigned)));
    FORGE_CUDA_CHECK(cudaMalloc((void**)&points, 2*npoints*sizeof(float)));
    FORGE_CUDA_CHECK(cudaMalloc((void**)&dirs, 2*npoints*sizeof(float)));

    GfxHandle* handles[3];

    createGLBuffer(&handles[0], divPoints.vertices(), FORGE_VERTEX_BUFFER);
    createGLBuffer(&handles[1], field.vertices(), FORGE_VERTEX_BUFFER);
    createGLBuffer(&handles[2], field.directions(), FORGE_VERTEX_BUFFER);

    FORGE_CUDA_CHECK(cudaMemcpy(dpoints, DPOINTS, 8*sizeof(unsigned), cudaMemcpyHostToDevice));
    generatePoints(points, dirs);

    copyToGLBuffer(handles[0], (ComputeResourceHandle)dpoints, divPoints.verticesSize());

    copyToGLBuffer(handles[1], (ComputeResourceHandle)points, field.verticesSize());
    copyToGLBuffer(handles[2], (ComputeResourceHandle)dirs, field.directionsSize());

    do {
        wnd.draw(chart);
    } while(!wnd.close());

    // destroy GL-CUDA interop buffers
    releaseGLBuffer(handles[0]);
    releaseGLBuffer(handles[1]);
    releaseGLBuffer(handles[2]);
    // destroy CUDA handles
    FORGE_CUDA_CHECK(cudaFree(dpoints));
    FORGE_CUDA_CHECK(cudaFree(points));
    FORGE_CUDA_CHECK(cudaFree(dirs));

    return 0;
}

__global__
void pointGenKernel(float* points, float* dirs, int nelems, float minimum, float step)
{
    int i = blockDim.x * blockIdx.x + threadIdx.x;
    int j = blockDim.y * blockIdx.y + threadIdx.y;

    if (i<nelems && j<nelems) {
        int id  = i + j * nelems;

        float x = minimum + i*step;
        float y = minimum + j*step;

        points[2*id+0] = x;
        points[2*id+1] = y;

        dirs[2*id+0] = sinf(2.0f*PI*x/10.f);
        dirs[2*id+1] = sinf(2.0f*PI*y/10.f);
    }
}

void generatePoints(float* points, float* dirs)
{
    static dim3 threads(8, 8);
    dim3 blocks(divup(NELEMS, threads.x),
                divup(NELEMS, threads.y));

    pointGenKernel<<<blocks, threads>>>(points, dirs, NELEMS, MINIMUM, STEP);
}
