/*
 * Copyright 1993-2015 NVIDIA Corporation.  All rights reserved.
 *
 * Please refer to the NVIDIA end user license agreement (EULA) associated
 * with this source code for terms and conditions that govern your use of
 * this software. Any use, reproduction, disclosure, or distribution of
 * this software and related documentation outside the terms of the EULA
 * is strictly prohibited.
 *
 */

#include "render_particles.h"

#include <cuda_runtime.h>
#include <cuda_gl_interop.h>

#include <helper_cuda.h>

#include <math.h>
#include <assert.h>

void mat_identity(matrix4 m)
{
    m[0][1] =
    m[0][2] =
    m[0][3] =
    m[1][0] =
    m[1][2] =
    m[1][3] =
    m[2][0] =
    m[2][1] =
    m[2][3] =
    m[3][0] =
    m[3][1] =
    m[3][2] = 0.0f;
    m[0][0] =
    m[1][1] =
    m[2][2] =
    m[3][3] = 1.0f;
}

void mat_multiply(matrix4 m0, matrix4 m1) 
{
    float m[4];

    for(int r = 0; r < 4; r++)
    {
        m[0] = m[1] = m[2] = m[3] = 0.0f;

        for(int c = 0; c < 4; c++)
        {
            for(int i = 0; i < 4; i++)
            {
                m[c] += m0[i][r] * m1[c][i];
            }
        }

        for(int c = 0; c < 4; c++)
        {
            m0[c][r] = m[c];
        }
    }   
}


void mat_translate(matrix4 m, vector3 v)
{
    matrix4 m2;
    m2[0][0] =
    m2[1][1] =
    m2[2][2] =
    m2[3][3] = 1.0f;
    m2[0][1] =
    m2[0][2] =
    m2[0][3] =
    m2[1][0] =
    m2[1][2] =
    m2[1][3] =
    m2[2][0] =
    m2[2][1] =
    m2[2][3] = 0.0f;
    m2[3][0] = v[0];
    m2[3][1] = v[1];
    m2[3][2] = v[2];
    mat_multiply(m, m2);
}

void mat_perspective(matrix4 m, GLfloat fovy, GLfloat aspect, GLfloat znear, GLfloat zfar)
{
    matrix4 m2;
    m2[1][0] =
    m2[2][0] =
    m2[3][0] =
    m2[0][1] =
    m2[2][1] =
    m2[3][1] =
    m2[0][2] =
    m2[1][2] =
    m2[0][3] =
    m2[1][3] =
    m2[3][3] = 0.0f;
    m2[2][3] = -1.0f;

    float f = 1 / tan( (fovy * M_PI / 180) /2);
    m2[0][0] = f / aspect;
    m2[1][1] = f;

    m2[2][2] = ( (znear + zfar) / (znear - zfar) );
    m2[3][2] = ( (2 * znear * zfar) / (znear - zfar) );

    mat_multiply(m, m2);
}

ParticleRenderer::ParticleRenderer(unsigned int windowWidth, unsigned int windowHeight)
    : m_pos(0),
      m_numParticles(0),
      m_pointSize(1.0f),
      m_spriteSize(2.0f),
      m_vertexShader(0),
      m_vertexShaderPoints(0),
      m_fragmentShader(0),
      m_programPoints(0),
      m_programSprites(0),
      m_texture(0),
      m_pbo(0),
      m_vboColor(0),
      m_windowWidth(windowWidth),
      m_windowHeight(windowHeight),
      m_bFp64Positions(false)
{
    m_camera[0] = 0;
    m_camera[1] = 0;
    m_camera[2] = 0;
    _initGL();
}

ParticleRenderer::~ParticleRenderer()
{
    m_pos = 0;
}

void ParticleRenderer::resetPBO()
{
    glDeleteBuffers(1, (GLuint *)&m_pbo);
}

void ParticleRenderer::setPositions(float *pos, int numParticles)
{
    m_pos = pos;
    m_numParticles = numParticles;

    if (!m_pbo)
    {
        glGenBuffers(1, (GLuint *)&m_pbo);
    }

    glBindBuffer(GL_ARRAY_BUFFER, m_pbo);
    glBufferData(GL_ARRAY_BUFFER, numParticles * 4 * sizeof(float), pos, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    checkGLErrors("Setting particle float position");
}

void ParticleRenderer::setPositions(double *pos, int numParticles)
{
    m_bFp64Positions = true;
    m_pos_fp64 = pos;
    m_numParticles = numParticles;

    if (!m_pbo)
    {
        glGenBuffers(1, (GLuint *)&m_pbo);
    }

    glBindBuffer(GL_ARRAY_BUFFER, m_pbo);
    glBufferData(GL_ARRAY_BUFFER, numParticles * 4 * sizeof(double), pos, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    checkGLErrors("Setting particle double position");
}

void ParticleRenderer::setColors(float *color, int numParticles)
{
    glBindBuffer(GL_ARRAY_BUFFER, m_vboColor);
    glBufferData(GL_ARRAY_BUFFER, numParticles * 4 * sizeof(float), color, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

void ParticleRenderer::setBaseColor(float color[4])
{
    for (int i = 0; i < 4; i++)
        m_baseColor[i] = color[i];
}

void ParticleRenderer::setPBO(unsigned int pbo, int numParticles, bool fp64)
{
    m_pbo = pbo;
    m_numParticles = numParticles;

    if (fp64)
        m_bFp64Positions = true;
}

void ParticleRenderer::display()
{
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE);
    glDepthMask(GL_FALSE);

    glUseProgram(m_programSprites);

    // Set modelview and projection matrices
    GLint h_ModelViewMatrix = glGetUniformLocation(m_programSprites, "modelview");
    GLint h_ProjectionMatrix = glGetUniformLocation(m_programSprites, "projection");
    matrix4 modelview;
    matrix4 projection;
    mat_identity(modelview);
    mat_identity(projection);
    mat_translate(modelview, m_camera);
    mat_perspective(projection, 60, (float)m_windowWidth / (float)m_windowHeight, 0.1, 1000.0);
    glUniformMatrix4fv(h_ModelViewMatrix, 1, GL_FALSE, (GLfloat*)modelview);
    glUniformMatrix4fv(h_ProjectionMatrix, 1, GL_FALSE, (GLfloat*)projection);

    // Set point size
    GLint h_PointSize = glGetUniformLocation(m_programSprites, "size");
    glUniform1f(h_PointSize, m_spriteSize);

    // Set base and secondary colors
    GLint h_BaseColor = glGetUniformLocation(m_programSprites, "baseColor");
    GLint h_SecondaryColor = glGetUniformLocation(m_programSprites, "secondaryColor");
    glUniform4f(h_BaseColor, 1.0, 1.0, 1.0, 1.0);
    glUniform4f(h_SecondaryColor, m_baseColor[0], m_baseColor[1], m_baseColor[2], m_baseColor[3]);

    // Set position coords
    GLint h_position = glGetAttribLocation(m_programSprites, "a_position");
    glBindBuffer(GL_ARRAY_BUFFER, m_pbo);
    glEnableVertexAttribArray(h_position);
    glVertexAttribPointer(h_position, 4, GL_FLOAT, GL_FALSE, 0, 0);

    GLuint texLoc = glGetUniformLocation(m_programSprites, "splatTexture");
    glUniform1i(texLoc, 0);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, m_texture);

    glDrawArrays(GL_POINTS, 0, m_numParticles);

    glDisableVertexAttribArray(h_position);

    glUseProgram(0);

    glDisable(GL_BLEND);
    glDepthMask(GL_TRUE);
}

const char vertexShader[] =
{
    "attribute vec4 a_position;"

    "uniform mat4 projection;"
    "uniform mat4 modelview;"
    "uniform float size;"

    "void main()"
    "{"
        "float pointSize = 500.0 * size;"
        "vec4 vert = a_position;"
        "vert.w = 1.0;"
        "vec3 pos_eye = vec3(modelview * vert);"
        "gl_PointSize = max(1.0, pointSize / (1.0 - pos_eye.z));"
        "gl_Position = projection * modelview * a_position;"
    "}"
};

const char fragmentShader[] =
{
    "uniform sampler2D splatTexture;"
    "uniform lowp vec4 baseColor;"
    "uniform lowp vec4 secondaryColor;"

    "void main()"
    "{"
        "lowp vec4 textureColor = (0.6 + 0.4 * baseColor) * texture2D(splatTexture, gl_PointCoord);"
        "gl_FragColor = textureColor * secondaryColor;"
    "}"
};

// Checks if the shader is compiled.
static int CheckCompiled(GLuint shader)
{
    GLint isCompiled = 0;
    glGetShaderiv(shader, GL_COMPILE_STATUS, &isCompiled);

    if (!isCompiled)
    {
        GLint infoLen = 0;
        glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);

        if (infoLen > 1)
        {
            char * infoLog = (char *) malloc(sizeof(char) * infoLen);

            glGetShaderInfoLog(shader, infoLen, NULL, infoLog);
            printf("Error compiling program:\n%s\n", infoLog);
            free(infoLog);
        }

        return 0;
    }

    return 1;
}

void ParticleRenderer::_initGL()
{
    m_vertexShader = glCreateShader(GL_VERTEX_SHADER);
    m_fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);

    const char *v = vertexShader;
    const char *f = fragmentShader;
    glShaderSource(m_vertexShader, 1, &v, 0);
    glShaderSource(m_fragmentShader, 1, &f, 0);

    checkGLErrors("Shader Source");

    glCompileShader(m_vertexShader);
    glCompileShader(m_fragmentShader);

    if (!CheckCompiled(m_vertexShader) || !CheckCompiled(m_fragmentShader))
    {
        printf("A shader failed to compile.\n");
        exit(1);
    }

    m_programSprites = glCreateProgram();

    checkGLErrors("create program");

    glAttachShader(m_programSprites, m_vertexShader);
    glAttachShader(m_programSprites, m_fragmentShader);

    checkGLErrors("attaching shaders");

    glLinkProgram(m_programSprites);

    checkGLErrors("linking program");

    EGLint linked;
    glGetProgramiv(m_programSprites, GL_LINK_STATUS, &linked);
    if (!linked)
    {
        printf ("A shader failed to link.\n");
        exit(1);
    }

    _createTexture(32);

    glGenBuffers(1, (GLuint *)&m_vboColor);
    glBindBuffer(GL_ARRAY_BUFFER, m_vboColor);
    glBufferData(GL_ARRAY_BUFFER, m_numParticles * 4 * sizeof(float), 0, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
}

//------------------------------------------------------------------------------
// Function           : EvalHermite
// Description      :
//------------------------------------------------------------------------------
/**
* EvalHermite(float pA, float pB, float vA, float vB, float u)
* @brief Evaluates Hermite basis functions for the specified coefficients.
*/
inline float evalHermite(float pA, float pB, float vA, float vB, float u)
{
    float u2=(u*u), u3=u2*u;
    float B0 = 2*u3 - 3*u2 + 1;
    float B1 = -2*u3 + 3*u2;
    float B2 = u3 - 2*u2 + u;
    float B3 = u3 - u;
    return (B0*pA + B1*pB + B2*vA + B3*vB);
}


unsigned char *createGaussianMap(int N)
{
    float *M = new float[2*N*N];
    unsigned char *B = new unsigned char[4*N*N];
    float X,Y,Y2,Dist;
    float Incr = 2.0f/N;
    int i=0;
    int j = 0;
    Y = -1.0f;

    //float mmax = 0;
    for (int y=0; y<N; y++, Y+=Incr)
    {
        Y2=Y*Y;
        X = -1.0f;

        for (int x=0; x<N; x++, X+=Incr, i+=2, j+=4)
        {
            Dist = (float)sqrtf(X*X+Y2);

            if (Dist>1) Dist=1;

            M[i+1] = M[i] = evalHermite(1.0f,0,0,0,Dist);
            B[j+3] = B[j+2] = B[j+1] = B[j] = (unsigned char)(M[i] * 255);
        }
    }

    delete [] M;
    return (B);
}

void ParticleRenderer::_createTexture(int resolution)
{
    unsigned char *data = createGaussianMap(resolution);
    glGenTextures(1, (GLuint *)&m_texture);
    glBindTexture(GL_TEXTURE_2D, m_texture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);//_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, resolution, resolution, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
}
