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#ifndef LLMR_GEOMETRY_BUFFER
#define LLMR_GEOMETRY_BUFFER
#include <cstdlib>
#include <cassert>
#include <llmr/platform/gl.hpp>
namespace llmr {
template <
size_t itemSize,
int bufferType = GL_ARRAY_BUFFER,
size_t defaultLength = 8192
>
class Buffer {
public:
~Buffer() {
if (array) {
free(array);
array = nullptr;
}
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;
}
// Transfers this buffer to the GPU and binds the buffer to the GL context.
void bind() {
if (buffer == 0) {
glGenBuffers(1, &buffer);
glBindBuffer(bufferType, buffer);
glBufferData(bufferType, pos, array, GL_STATIC_DRAW);
free(array);
array = nullptr;
} else {
glBindBuffer(bufferType, buffer);
}
}
protected:
// increase the buffer size by at least /required/ bytes.
void *addElement() {
assert("Buffer is already bound to GPU" && buffer == 0);
if (length < pos + itemSize) {
while (length < pos + itemSize) length += defaultLength;
array = realloc(array, length);
assert("Buffer reallocation failed" && array != nullptr);
}
pos += itemSize;
return static_cast<char *>(array) + (pos - itemSize);
}
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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