118 lines
3.4 KiB
C++
118 lines
3.4 KiB
C++
#include <GL/glew.h>
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#include "../stb_image.h"
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#include "loader.h"
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namespace render_engine
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{
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namespace loader
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{
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static GLuint CreateVao();
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static void StoreDataInAttributeList(int attribute_number, int coordinate_size, std::vector<float>& data);
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static void BindIndicesBuffer(std::vector<unsigned int>& indices);
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static std::vector<GLuint> vaos;
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static std::vector<GLuint> vbos;
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static std::vector<GLuint> textures;
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/*
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This function will generate a Model from vertex positions, textureCoordinates and indices.
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*/
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struct models::RawModel LoadToVAO(std::vector<float>& positions, std::vector<float>& texture_coords, std::vector<unsigned int>& indices)
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{
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GLuint vao_id = CreateVao();
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BindIndicesBuffer(indices);
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StoreDataInAttributeList(0, 3, positions);
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StoreDataInAttributeList(1, 2, texture_coords);
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glBindVertexArray(0);
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return { vao_id, static_cast<int>(indices.size()) };
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}
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/*
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Loads an image as texture into openGL
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*/
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GLuint LoadTexture(std::string file_name)
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{
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int width, height, bpp;
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unsigned char* imgData = stbi_load(file_name.c_str(), &width, &height, &bpp, 4);
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GLuint texture_id;
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glGenTextures(1, &texture_id);
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glEnable(GL_TEXTURE_2D);
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glBindTexture(GL_TEXTURE_2D, texture_id);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imgData);
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glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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stbi_image_free(imgData);
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textures.push_back(texture_id);
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return texture_id;
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}
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/*
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This function will delete all the vectors declared at the top of this file from openGL.
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*/
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void CleanUp()
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{
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glDeleteVertexArrays(static_cast<GLsizei>(vaos.size()), &vaos[0]);
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glDeleteBuffers(static_cast<GLsizei>(vbos.size()), &vbos[0]);
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glDeleteTextures(static_cast<GLsizei>(textures.size()), &textures[0]);
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}
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/*
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This function will create a new VAO for a new mesh.
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*/
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static GLuint CreateVao()
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{
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GLuint vao_id;
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glGenVertexArrays(1, &vao_id);
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vaos.push_back(vao_id);
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glBindVertexArray(vao_id);
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return vao_id;
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}
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/*
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This function can store data (vbo) in a vao.
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*/
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static void StoreDataInAttributeList(int attribute_number, int coordinate_size, std::vector<float>& data)
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{
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GLuint vbo_id;
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glGenBuffers(1, &vbo_id);
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vbos.push_back(vbo_id);
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glBindBuffer(GL_ARRAY_BUFFER, vbo_id);
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glBufferData(GL_ARRAY_BUFFER, sizeof(float) * data.size(), &data[0], GL_STATIC_DRAW);
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glVertexAttribPointer(attribute_number, coordinate_size, GL_FLOAT, GL_FALSE, 0, 0);
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glBindBuffer(GL_ARRAY_BUFFER, 0);
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}
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/*
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This functions loads a indices buffer and binds it to a vao.
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(Using this method of rendering is way more effici<63>nt with large/complex meshes.
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This way you won't have to specify double or more occuring vertices. You just use sort of a lookup table
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to choose which vertex to get)
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Example:
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std::vector<float> vertices =
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{
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-0.5f, 0.5f, 0,
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-0.5f, -0.5f, 0,
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0.5f, -0.5f, 0,
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0.5f, 0.5f, 0
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};
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std::vector<int> indices =
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{
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0,1,3,
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3,1,2
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};
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*/
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static void BindIndicesBuffer(std::vector<unsigned int>& indices)
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{
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GLuint vbo_id;
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glGenBuffers(1, &vbo_id);
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vbos.push_back(vbo_id);
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glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vbo_id);
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glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(int) * indices.size(), &indices[0], GL_STATIC_DRAW);
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}
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}
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}
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