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#pragma once
#include <mbgl/gl/gl.hpp>
#include <mbgl/gl/object_store.hpp>
#include <mbgl/platform/log.hpp>
#include <mbgl/util/noncopyable.hpp>
#include <mbgl/util/optional.hpp>
#include <memory>
#include <cstdlib>
#include <cassert>
#include <stdexcept>
namespace mbgl {
template <
GLsizei item_size,
GLenum bufferType = GL_ARRAY_BUFFER,
GLsizei defaultLength = 8192,
bool retainAfterUpload = false
>
class Buffer : private util::noncopyable {
public:
~Buffer() {
cleanup();
}
// Returns the number of elements in this buffer. This is not the number of
// bytes, but rather the number of coordinates with associated information.
GLsizei index() const {
return static_cast<GLsizei>(pos / itemSize);
}
bool empty() const {
return pos == 0;
}
// Transfers this buffer to the GPU and binds the buffer to the GL context.
void bind(gl::ObjectStore& store) {
if (buffer) {
MBGL_CHECK_ERROR(glBindBuffer(bufferType, *buffer));
} else {
buffer = store.createBuffer();
MBGL_CHECK_ERROR(glBindBuffer(bufferType, *buffer));
if (array == nullptr) {
Log::Debug(Event::OpenGL, "Buffer doesn't contain elements");
pos = 0;
}
MBGL_CHECK_ERROR(glBufferData(bufferType, pos, array, GL_STATIC_DRAW));
if (!retainAfterUpload) {
cleanup();
}
}
}
void cleanup() {
if (array) {
free(array);
array = nullptr;
}
}
GLuint getID() const {
return buffer ? *buffer : 0;
}
// Uploads the buffer to the GPU to be available when we need it.
void upload(gl::ObjectStore& store) {
if (!buffer) {
bind(store);
}
}
protected:
// increase the buffer size by at least /required/ bytes.
void *addElement() {
if (buffer) {
throw std::runtime_error("Can't add elements after buffer was bound to GPU");
}
if (length < pos + itemSize) {
while (length < pos + itemSize) length += defaultLength;
array = realloc(array, length);
if (array == nullptr) {
throw std::runtime_error("Buffer reallocation failed");
}
}
pos += itemSize;
return reinterpret_cast<char *>(array) + (pos - itemSize);
}
public:
static const size_t itemSize = item_size;
private:
// CPU buffer
GLvoid *array = nullptr;
// Byte position where we are writing.
GLsizeiptr pos = 0;
// Number of bytes that are valid in this buffer.
size_t length = 0;
// GL buffer object handle.
mbgl::optional<gl::UniqueBuffer> buffer;
};
} // namespace mbgl
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