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// external libs
#include "glad/glad.h"
// project headers
#include "batch.hpp"
#include "texture.hpp"
// std libs
#include <vector>
#include <iostream>
Batch::Batch(unsigned int batch_limit)
{
this->batch_limit = batch_limit;
glGenBuffers(1, &VBO); // generate the buffer
glGenBuffers(1, &EBO);
glGenVertexArrays(1, &VAO); // generate array
glBindVertexArray(VAO); // bind array to apply "settings" to it
glBindBuffer(GL_ARRAY_BUFFER, VBO); // bind(activate) the buffer to the ARRAY_BUFFER
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
// position attribute
GLsizei stride = 10 * sizeof(float);
glVertexAttribPointer(
0, // index
3, // size(number of elements)
GL_FLOAT,
GL_FALSE,
stride, // stride(distance to reach next one)
(void*)0); // pointer(offset from start)
glEnableVertexAttribArray(0);
// color attribute
glVertexAttribPointer(
1,
4,
GL_FLOAT,
GL_FALSE,
stride,
(void*)(3 * sizeof(float))); // configure how the vertex array looks
glEnableVertexAttribArray(1);
//texture coordinates
glVertexAttribPointer(
2,
2,
GL_FLOAT,
GL_FALSE,
stride,
(void*)(7 * sizeof(float))); // configure how the vertex array looks
glEnableVertexAttribArray(2);
//texture id
glVertexAttribPointer(
3,
1,
GL_FLOAT,
GL_FALSE,
stride,
(void*)(9 * sizeof(float))); // configure how the vertex array looks
glEnableVertexAttribArray(3);
}
int Batch::drawTexture(
Texture texture,
float x,
float y,
float width,
float height,
glm::vec4 color
)
{
float h_height = height / 2.0;
float h_width = width / 2.0;
return this->primativeDrawQuad(
texture.id,
glm::vec3(x+h_height,y+h_width, -1.0f), // top right
glm::vec3(x+h_height, y-h_width, -1.0f), // bottom right
glm::vec3(x-h_height, y-h_width, -1.0f), // bottom left
glm::vec3(x-h_height, y+h_height, -1.0f), // top left
color
);
}
int Batch::drawRectangle(
float x,
float y,
float width,
float height,
glm::vec4 color
)
{
float h_height = height / 2.0;
float h_width = width / 2.0;
return this->primativeDrawQuad(
0,
glm::vec3(x+h_height,y+h_width, -1.0f), // top right
glm::vec3(x+h_height, y-h_width, -1.0f), // bottom right
glm::vec3(x-h_height, y-h_width, -1.0f), // bottom left
glm::vec3(x-h_height, y+h_height, -1.0f), // top left
color
);
}
int Batch::primativeDrawQuad(
unsigned int texture_id,
glm::vec3 a,
glm::vec3 b,
glm::vec3 c,
glm::vec3 d,
glm::vec4 color
)
{
// if no assigned texture, attempt to assign it
if(texture_id == 0)
last_texture = texture_id;
// if surpassing batch limit
// or if texture is different
if((size >= batch_limit) || ((last_texture != texture_id) && (texture_id != 0)))
this->flush(); last_texture = texture_id;
float verts[] = {
// top right
a.x, a.y, a.z, // position
color.r, color.g, color.b, color.a, // colors
1.0f, 1.0f, // tex coords
(float)texture_id, // tex id(0 means none)
// bottom right
b.x, b.y, b.z,
color.r, color.g, color.b, color.a,
1.0f, 0.0f,
(float)texture_id,
// bottom left
c.x, c.y, c.z,
color.r, color.g, color.b, color.a,
0.0f, 0.0f,
(float)texture_id,
// top left
d.x, d.y, d.z,
color.r, color.g, color.b, color.a,
0.0f, 1.0f,
(float)texture_id
};
unsigned int inds[] = {
(size * 4) + 0, (size * 4) + 1, (size * 4) + 3, // first triangle
(size * 4) + 1, (size * 4) + 2, (size * 4) + 3, // second triangle
};
vertices.reserve(sizeof(verts));
indices.reserve(sizeof(inds));
vertices.insert(vertices.end(), std::cbegin(verts), std::cend(verts));
indices.insert(indices.end(), std::cbegin(inds), std::cend(inds));
size += 1;
return 0;
}
void Batch::flush()
{
glBindVertexArray(VAO);
// we already binded this in the VAO during initialization
// so no need to do it again
//glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData( // uploading vertices
GL_ARRAY_BUFFER,
vertices.size() * sizeof(float),
vertices.data(),
GL_DYNAMIC_DRAW
);
// we already binded this in the VAO during initialization
// so no need to do it again
//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData( // uploading indices
GL_ELEMENT_ARRAY_BUFFER,
indices.size() * sizeof(unsigned int),
indices.data(),
GL_DYNAMIC_DRAW
);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, last_texture);
glDrawElements(GL_TRIANGLES, 6 * size, GL_UNSIGNED_INT, 0);
glBindVertexArray(0); // unbind the VAO
last_texture = 0;
size = 0;
vertices.clear();
indices.clear();
}
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