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/** ---------------------------------------------------------------------------
* -*- c++ -*-
* @file: spritebatch.cpp
*
* Copyright (c) 2017 Yann Herklotz Grave <ymherklotz@gmail.com>
* MIT License, see LICENSE file for more details.
* ----------------------------------------------------------------------------
*/
#include "spritebatch.h"
#include "../core/logger.h"
#include <algorithm>
#include <iostream>
#include <stdexcept>
using std::cout;
#include <GLFW/glfw3.h>
namespace yage
{
const int SpriteBatch::NUM_VERTICES;
SpriteBatch::SpriteBatch() : vao_(0), vbo_(0)
{
glGenVertexArrays(1, &vao_);
if (vao_ == 0) {
throw std::runtime_error("failed to generate VAO");
}
// bind vertex array object
glBindVertexArray(vao_);
glGenBuffers(1, &vbo_);
if (vbo_ == 0) {
throw std::runtime_error("failed to generate VBO");
}
// bind vertex buffer object
glBindBuffer(GL_ARRAY_BUFFER, vbo_);
// set the vertex attribute pointers
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex),
(void *)offsetof(Vertex, position));
glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(Vertex),
(void *)offsetof(Vertex, colour));
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex),
(void *)offsetof(Vertex, uv));
// enable vertex attribute arrays
glEnableVertexAttribArray(0);
glEnableVertexAttribArray(1);
glEnableVertexAttribArray(2);
}
SpriteBatch::~SpriteBatch()
{
if (vbo_ != 0) {
glDeleteBuffers(1, &vbo_);
}
if (vao_ != 0) {
glDeleteVertexArrays(1, &vao_);
}
}
void SpriteBatch::begin()
{
glyphs_.clear();
glyph_ptrs_.clear();
render_batches_.clear();
}
void SpriteBatch::end()
{
sortGlyphs();
createRenderBatches();
}
void SpriteBatch::draw(const glm::vec4 &destination_rect,
const glm::vec4 &uv_rect, GLuint texture,
const Colour &colour, float depth)
{
Vertex top_left, top_right, bottom_right, bottom_left;
top_left.colour = colour;
top_left.setPosition(destination_rect.x,
destination_rect.y + destination_rect.w);
top_left.setUv(uv_rect.x, uv_rect.y + uv_rect.w);
top_right.colour = colour;
top_right.setPosition(destination_rect.x + destination_rect.z,
destination_rect.y + destination_rect.w);
top_right.setUv(uv_rect.x + uv_rect.z, uv_rect.y + uv_rect.w);
bottom_right.colour = colour;
bottom_right.setPosition(destination_rect.x + destination_rect.z,
destination_rect.y);
bottom_right.setUv(uv_rect.x + uv_rect.z, uv_rect.y);
bottom_left.colour = colour;
bottom_left.setPosition(destination_rect.x, destination_rect.y);
bottom_left.setUv(uv_rect.x, uv_rect.y);
// deal with fragmenting by creating vector of pointers
glyphs_.emplace_back(texture, depth, top_left, top_right, bottom_right,
bottom_left);
}
void SpriteBatch::render()
{
glBindVertexArray(vao_);
// sort and create render batches
sortGlyphs();
createRenderBatches();
glActiveTexture(GL_TEXTURE0);
for (auto &&batch : render_batches_) {
yLogDebug << "Drawing " << batch.num_vertices
<< " vertices bound to texture: " << batch.texture;
glBindTexture(GL_TEXTURE_2D, batch.texture);
glDrawArrays(GL_TRIANGLES, batch.offset, batch.num_vertices);
}
// clear and reset the vectors
glyphs_.clear();
glyph_ptrs_.clear();
render_batches_.clear();
}
void SpriteBatch::createRenderBatches()
{
std::vector<Vertex> vertices;
if (glyph_ptrs_.empty()) {
return;
}
vertices.reserve(glyph_ptrs_.size() * NUM_VERTICES);
for (int i = 0; i < (int)glyph_ptrs_.size(); ++i) {
if (i == 0 || (i > 0 && (glyph_ptrs_[i]->texture !=
glyph_ptrs_[i - 1]->texture))) {
render_batches_.emplace_back(i * NUM_VERTICES, NUM_VERTICES,
glyph_ptrs_[i]->texture);
} else {
render_batches_.back().num_vertices += NUM_VERTICES;
}
vertices.push_back(glyph_ptrs_[i]->bottom_left);
vertices.push_back(glyph_ptrs_[i]->top_left);
vertices.push_back(glyph_ptrs_[i]->top_right);
vertices.push_back(glyph_ptrs_[i]->top_right);
vertices.push_back(glyph_ptrs_[i]->bottom_right);
vertices.push_back(glyph_ptrs_[i]->bottom_left);
}
// orphan the buffer
glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(Vertex), nullptr,
GL_DYNAMIC_DRAW);
glBufferSubData(GL_ARRAY_BUFFER, 0, vertices.size() * sizeof(Vertex),
vertices.data());
}
void SpriteBatch::sortGlyphs()
{
glyph_ptrs_.reserve(glyphs_.size());
for (auto &glyph : glyphs_) {
glyph_ptrs_.push_back(&glyph);
}
// sort using introsort or quicksort
std::sort(glyph_ptrs_.begin(), glyph_ptrs_.end(),
[](details::Glyph *a, details::Glyph *b) -> bool {
if (a->depth == b->depth) {
return a->texture < b->texture;
}
return a->depth < b->depth;
});
}
} // namespace yage
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