#include "skybox.h"
#include "glassert.h"
#include "shader.h"
#include "material.h"
#include "skyboxmaterial.h"
#include "glm/glm.hpp"
#include "glm/ext.hpp"

SkyBox::SkyBox(const QString filename[6]) : Entity(NULL, NULL, NULL)
{
    Shader* shader = new Shader(&vertSource, &fragSource);
    mat = new SkyBoxMaterial(shader, filename);

    // set up vao
    glAssert(glGenVertexArrays(1, &vao));
    glAssert(glBindVertexArray(vao));
    glAssert(glGenBuffers(1, &vbo));
    glAssert(glBindBuffer(GL_ARRAY_BUFFER, vbo));
    glAssert(glBufferData(GL_ARRAY_BUFFER, 108 * sizeof(GLfloat), skyboxVertices, GL_STATIC_DRAW));
    glAssert(glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(float)*3, NULL));
    glAssert(glEnableVertexAttribArray(0));
    glAssert(glBindVertexArray(0));
}

SkyBox::~SkyBox()
{
    glAssert(glDeleteVertexArrays(1, &vao));
    glAssert(glDeleteBuffers(1, &vbo));
}

void SkyBox::draw(const glm::mat4 viewMatrix, const glm::mat4 projectionMatrix)
{
    glm::mat4 mvp = projectionMatrix * glm::mat4(glm::mat3(viewMatrix));
    glAssert(glDepthMask(GL_FALSE));
    mat->bindAttributes();
    Shader* shader = mat->getShader();
    shader->bindMatrix(shader->getLocation("MVP"), mvp);
    glAssert(glBindVertexArray(vao));
    glAssert(glDrawArrays(GL_TRIANGLES, 0, 36));
    glAssert(glDepthMask(GL_TRUE));
}

const GLfloat SkyBox::skyboxVertices[] = {
    -1.0f,  1.0f, -1.0f,
    -1.0f, -1.0f, -1.0f,
     1.0f, -1.0f, -1.0f,
     1.0f, -1.0f, -1.0f,
     1.0f,  1.0f, -1.0f,
    -1.0f,  1.0f, -1.0f,

    -1.0f, -1.0f,  1.0f,
    -1.0f, -1.0f, -1.0f,
    -1.0f,  1.0f, -1.0f,
    -1.0f,  1.0f, -1.0f,
    -1.0f,  1.0f,  1.0f,
    -1.0f, -1.0f,  1.0f,

     1.0f, -1.0f, -1.0f,
     1.0f, -1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f,  1.0f, -1.0f,
     1.0f, -1.0f, -1.0f,

    -1.0f, -1.0f,  1.0f,
    -1.0f,  1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f, -1.0f,  1.0f,
    -1.0f, -1.0f,  1.0f,

    -1.0f,  1.0f, -1.0f,
     1.0f,  1.0f, -1.0f,
     1.0f,  1.0f,  1.0f,
     1.0f,  1.0f,  1.0f,
    -1.0f,  1.0f,  1.0f,
    -1.0f,  1.0f, -1.0f,

    -1.0f, -1.0f, -1.0f,
    -1.0f, -1.0f,  1.0f,
     1.0f, -1.0f, -1.0f,
     1.0f, -1.0f, -1.0f,
    -1.0f, -1.0f,  1.0f,
     1.0f, -1.0f,  1.0f
};

const QString SkyBox::vertSource =
        "#version 330 core\n\
        layout(location = 0)in vec3 inPosition;\n\
        out vec3 varTexCoord;\n\
        uniform mat4 MVP;\n\
        void main()\n\
        {\n\
            gl_Position = MVP * vec4(inPosition, 1.0);\n\
            varTexCoord = inPosition;\n\
        }\n";

const QString SkyBox::fragSource =
        "#version 330 core\n\
        in vec3 varTexCoord;\n\
        out vec4 outColor;\n\
        uniform samplerCube skybox;\n\
        void main()\n\
        {\n\
            outColor = texture(skybox, varTexCoord);\n\
        }\n";