OpenSubdiv/opensubdiv/osd/cpuGLVertexBuffer.cpp

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#include "../osd/cpuGLVertexBuffer.h"

#include "../osd/opengl.h"

#include <string.h>

namespace OpenSubdiv {
namespace OPENSUBDIV_VERSION {

OsdCpuGLVertexBuffer::OsdCpuGLVertexBuffer(int numElements, int numVertices)
    : _numElements(numElements), _numVertices(numVertices),
      _vbo(0), _cpuBuffer(0), _dataDirty(true) {
}

OsdCpuGLVertexBuffer::~OsdCpuGLVertexBuffer() {

    delete[] _cpuBuffer;
    glDeleteBuffers(1, &_vbo);
}

OsdCpuGLVertexBuffer *
OsdCpuGLVertexBuffer::Create(int numElements, int numVertices) {
    OsdCpuGLVertexBuffer *instance =
        new OsdCpuGLVertexBuffer(numElements, numVertices);
    if (instance->allocate()) return instance;
    delete instance;
    return NULL;
}

void
OsdCpuGLVertexBuffer::UpdateData(const float *src, int startVertex, int numVertices) {

    memcpy(_cpuBuffer + startVertex * GetNumElements(), src, GetNumElements() * numVertices * sizeof(float));
    _dataDirty = true;
}

int
OsdCpuGLVertexBuffer::GetNumElements() const {

    return _numElements;
}

int
OsdCpuGLVertexBuffer::GetNumVertices() const {

    return _numVertices;
}

float*
OsdCpuGLVertexBuffer::BindCpuBuffer() {
    _dataDirty = true; // caller might modify data
    return _cpuBuffer;
}

GLuint
OsdCpuGLVertexBuffer::BindVBO() {
    if (not _dataDirty)
        return _vbo;

    int size = GetNumElements() * GetNumVertices() * sizeof(float);

    glBindBuffer(GL_ARRAY_BUFFER, _vbo);
    glBufferData(GL_ARRAY_BUFFER, size, _cpuBuffer, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    _dataDirty = false;
    return _vbo;
}

bool
OsdCpuGLVertexBuffer::allocate() {
    _cpuBuffer = new float[GetNumElements() * GetNumVertices()];
    _dataDirty = true;
    int size = GetNumElements() * GetNumVertices() * sizeof(float);

    glGenBuffers(1, &_vbo);
    glBindBuffer(GL_ARRAY_BUFFER, _vbo);
    glBufferData(GL_ARRAY_BUFFER, size, 0, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    if (glGetError() == GL_NO_ERROR) return true;
    return false;
}

}  // end namespace OPENSUBDIV_VERSION
}  // end namespace OpenSubdiv