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#ifndef MBGL_GEOMETRY_BUFFER
#define MBGL_GEOMETRY_BUFFER
#include <mbgl/platform/gl.hpp>
#include <mbgl/util/noncopyable.hpp>
#include <cstdlib>
#include <cassert>
#include <stdexcept>
namespace mbgl {
template <
size_t item_size,
int bufferType = GL_ARRAY_BUFFER,
size_t defaultLength = 8192,
bool retainAfterUpload = false
>
class Buffer : private util::noncopyable {
public:
~Buffer() {
cleanup();
if (buffer != 0) {
glDeleteBuffers(1, &buffer);
buffer = 0;
}
}
// Returns the number of elements in this buffer. This is not the number of
// bytes, but rather the number of coordinates with associated information.
inline size_t index() const {
return pos / itemSize;
}
inline bool empty() const {
return pos == 0;
}
// Transfers this buffer to the GPU and binds the buffer to the GL context.
void bind(bool force = false) {
if (buffer == 0) {
glGenBuffers(1, &buffer);
force = true;
}
glBindBuffer(bufferType, buffer);
if (force) {
if (array == nullptr) {
throw std::runtime_error("Buffer was already deleted or doesn't contain elements");
}
glBufferData(bufferType, pos, array, GL_STATIC_DRAW);
if (!retainAfterUpload) {
cleanup();
}
}
}
void cleanup() {
if (array) {
free(array);
array = nullptr;
}
}
protected:
// increase the buffer size by at least /required/ bytes.
inline void *addElement() {
if (buffer != 0) {
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 static_cast<char *>(array) + (pos - itemSize);
}
// Get a pointer to the item at a given index.
inline void *getElement(size_t index) {
if (array == nullptr) {
throw std::runtime_error("Buffer was already deleted or doesn't contain elements");
}
if (index * itemSize >= pos) {
throw new std::runtime_error("Can't get element after array bounds");
} else {
return static_cast<char *>(array) + (index * itemSize);
}
}
public:
static const size_t itemSize = item_size;
private:
// CPU buffer
void *array = nullptr;
// Byte position where we are writing.
size_t pos = 0;
// Number of bytes that are valid in this buffer.
size_t length = 0;
// GL buffer ID
uint32_t buffer = 0;
};
}
#endif
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