GeometricObject.cpp

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#include <iostream>
#include "GeometricObject.h"

using namespace vis2;

GeometricObject::GeometricObject(   glm::mat4 _modelMatrix,
                                    Shader* _shader, 
                                    const float* _positions_Ptr,
                                    const unsigned int _pos_size,
                                    const float* _normals_Ptr,
                                    const unsigned int _norm_size,
                                    const unsigned int* _index_Ptr,
                                    const unsigned int _ind_size)
    : DrawableObject(_modelMatrix), shader_Ptr(_shader), index_count(_ind_size)
{
    // ------------------------- LOAD VBOs ----------------------------------- //
    // load positions to buffer
    glGenBuffers(1,&position_buffer_handle); // takes n, array of handles as well
    glBindBuffer(GL_ARRAY_BUFFER, position_buffer_handle); // activate buffer
    glBufferData(GL_ARRAY_BUFFER, _pos_size * 3 * sizeof(float), _positions_Ptr, GL_STATIC_DRAW); // load data
    glBindBuffer(GL_ARRAY_BUFFER,0); // deactivate buffer

    // load normals to buffer
    glGenBuffers(1,&normal_buffer_handle);
    glBindBuffer(GL_ARRAY_BUFFER, normal_buffer_handle);
    glBufferData(GL_ARRAY_BUFFER, _norm_size * 3 * sizeof(float), _normals_Ptr, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER,0);

    // load face indices to buffer
    glGenBuffers(1,&index_buffer_handle);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_handle);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, _ind_size * sizeof(unsigned int), _index_Ptr, GL_STATIC_DRAW);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,0);

    // ------------------------- BIND VBOs to VAO ----------------------------------- //
    // bind vao
    glGenVertexArrays(1,&vao_handle);
    glBindVertexArray(vao_handle);

    // bind positions
    glBindBuffer(GL_ARRAY_BUFFER,position_buffer_handle); // bind vbo to vao
    GLint shader_in_position_handle = glGetAttribLocation(shader_Ptr->program_handle,"position"); // get handle of the in vars from shader
    glEnableVertexAttribArray(shader_in_position_handle); // communicate handle to vao
    glVertexAttribPointer(shader_in_position_handle, 3, GL_FLOAT, GL_FALSE, 0, 0); // specify array elems size and if they should be normalized

    // bind normals
    glBindBuffer(GL_ARRAY_BUFFER,normal_buffer_handle);
    GLint shader_in_normal_handle = glGetAttribLocation(shader_Ptr->program_handle,"normal");
    glEnableVertexAttribArray(shader_in_normal_handle);
    glVertexAttribPointer(shader_in_normal_handle, 3, GL_FLOAT, GL_FALSE, 0, 0);

    // bind indices
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, index_buffer_handle);

    // ------------------------- DEACTIVATE ALL BUFFERS ----------------------------- //
    glBindVertexArray(0); // deactivate vao
    glBindBuffer(GL_ARRAY_BUFFER, 0); // deactivate vbo
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); // deactivate vbo

}

GeometricObject::~GeometricObject()
{
    glDeleteBuffers(1,&position_buffer_handle);
    glDeleteBuffers(1,&normal_buffer_handle);
    glDeleteBuffers(1,&index_buffer_handle);
    glDeleteVertexArrays(1,&vao_handle);
}

        
void GeometricObject::draw(glm::mat4 &_projectionMatrix)
{
    // activate shader
    this->shader_Ptr->useShader();
    // pass uniforms to shader of the object
    glUniformMatrix4fv( glGetUniformLocation(shader_Ptr->program_handle,"projectionMatrix"),
                        1,
                        GL_FALSE,
                        glm::value_ptr(_projectionMatrix));
    glUniformMatrix4fv( glGetUniformLocation(this->shader_Ptr->program_handle, "modelMatrix"),
                        1,
                        GL_FALSE,
                        glm::value_ptr(this->modelMatrix));
    
    // activate vao
    glBindVertexArray(vao_handle);
    // place draw call with the vao above
    glDrawElements(GL_TRIANGLES, this->index_count, GL_UNSIGNED_INT,0);
    // deactivate vao
    glBindVertexArray(0);

    // deactivate shader
    this->shader_Ptr->releaseShader();
}