我需要用新的顶点更新网格。我这样创建VBO（最初创建时只有一个顶点）：
public Mesh(float[] vertex, int size)
{
texture = null;
meshType = 1; //will draw lines
FloatBuffer verticesBuffer = null;
IntBuffer indicesBuffer = null;
int vboID;
try
{
vertexCount = size;
vaoID = glGenVertexArrays();
glBindVertexArray(vaoID);
vboIDList = new ArrayList<>();
// Vertices VBO generation
vboID = glGenBuffers();
vboIDList.add(vboID);
verticesBuffer = MemoryUtil.memAllocFloat(size * 3); // !!! Must Be manually freed!
verticesBuffer.put(vertex).flip();
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferData(GL_ARRAY_BUFFER, verticesBuffer, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
vertexAttrArrCount += 1;
// Indices VBO generation
vboID = glGenBuffers();
vboIDList.add(vboID);
indicesBuffer = MemoryUtil.memAllocInt(size); // !!! Must be manually freed!
indicesBuffer.put(new int[]{0}).flip();
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indicesBuffer, GL_STATIC_DRAW);
// unbinding
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
finally
{
if (verticesBuffer != null)
{
MemoryUtil.memFree(verticesBuffer); // Freeing vertex buffer
}
if (indicesBuffer != null)
{
MemoryUtil.memFree(indicesBuffer); // Freeing indices buffer
}
}
}
然后我要更新VBO缓冲区并将新的顶点写入其中。请注意，我确实创建了VBO，以为新顶点留有足够的空间，并且控制了它不会被过度填充。我还控制了每个渲染调用绘制的元素数量，因此不会绘制空的0/0/0顶点。
我的问题是，此代码有效：
public void updateVBO(float[] vertices, int[] indices, int size)
{
if (meshType == 1)
{
lineCount = size;
FloatBuffer subDataF = null;
IntBuffer subDataI = null;
int vboID;
try
{
//System.out.printf("Adding vertex (%f, %f, %f) to position %d\n",vertex.x,vertex.y,vertex.z,position);
vboID = vboIDList.get(0);
//float[] vert = new float[]{vertex.x, vertex.y, vertex.z};
subDataF = MemoryUtil.memAllocFloat(vertices.length); // !!! Must Be manually freed!
subDataF.put(vertices).flip();
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferData(GL_ARRAY_BUFFER, subDataF, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
vboID = vboIDList.get(1);
//int[] index = new int[]{ position };
subDataI = MemoryUtil.memAllocInt(indices.length); // !!! Must Be manually freed!
subDataI.put(indices).flip();
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, subDataI, GL_STATIC_DRAW);
//glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
finally
{
if (subDataF != null)
{
MemoryUtil.memFree(subDataF);
}
if (subDataI != null)
{
MemoryUtil.memFree(subDataI);
}
}
}
}
因此，当我传递整个顶点数组并从头开始重新分配VBO内存时，它恰好绘制了我所需的内容。 但是我想使用glBufferSubData，这样我每次添加新顶点时都不会重新分配内存。 这段代码不起作用：
public void addVertex(Vector3f vertex, int position)
{
if (meshType == 1)
{
FloatBuffer subDataF = null;
IntBuffer subDataI = null;
int vboID;
lineCount = position+1;
try
{
System.out.printf("Adding vertex (%f, %f, %f) to position %d\n",vertex.x,vertex.y,vertex.z,position);
vboID = vboIDList.get(0);
float[] vert = new float[]{vertex.x, vertex.y, vertex.z};
subDataF = MemoryUtil.memAllocFloat(3); // !!! Must Be manually freed!
subDataF.put(vert).flip();
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferSubData(GL_ARRAY_BUFFER, position * 3 * 4, subDataF);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
vboID = vboIDList.get(1);
int[] index = new int[]{ position };
subDataI = MemoryUtil.memAllocInt(1); // !!! Must Be manually freed!
subDataI.put(index).flip();
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboID);
glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, position * 4, subDataI);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
finally
{
if (subDataF != null)
{
MemoryUtil.memFree(subDataF);
}
if (subDataI != null)
{
MemoryUtil.memFree(subDataI);
}
}
}
}
我也知道它没有优化创建floatbuffer和intbuffer的方式，我只是想在清理之前使其工作。我正在尝试很多事情，因此，最后一段代码很奇怪。
还是，我不明白我在做什么错。我确实检查了我是否正确传递了所有数据，并且似乎计算了位置（和偏移量）的大小。它只是什么也没画，而当我使用glBufferData时却画了。
有人可以解释我在哪里犯错吗？
经过所有建议，这就是我的最终目的，但是它仍然根本不起作用：
public void addVertex(Vector3f vertex, int position)
{
if (meshType == 1)
{
FloatBuffer subDataF = null;
IntBuffer subDataI = null;
int vboID;
lineCount = position+1;
try
{
System.out.printf("Adding vertex (%f, %f, %f) to position %d\n",vertex.x,vertex.y,vertex.z,position);
vboID = vboIDList.get(0);
float[] vert = new float[]{vertex.x, vertex.y, vertex.z};
subDataF = MemoryUtil.memAllocFloat(3); // !!! Must Be manually freed!
subDataF.put(vert).flip();
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferSubData(GL_ARRAY_BUFFER, (long)(position * 3 * 4), (FloatBuffer)subDataF);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
vboID = vboIDList.get(1);
int[] index = new int[]{ position };
subDataI = MemoryUtil.memAllocInt(1); // !!! Must Be manually freed!
subDataI.put(index).flip();
glBindVertexArray(vaoID);
glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, (long)(position * 4), (IntBuffer)subDataI);
}
finally
{
if (subDataF != null)
{
MemoryUtil.memFree(subDataF);
}
if (subDataI != null)
{
MemoryUtil.memFree(subDataI);
}
}
}
}
我确实检查了VAO ID是否正确。
答案 0 :(得分：0)
就像我想的那样，这很愚蠢，根本与VAO绑定无关。
问题是，当我最初创建VBO时，我是这样做的：
// Vertices VBO generation
vboID = glGenBuffers();
vboIDList.add(vboID);
verticesBuffer = MemoryUtil.memAllocFloat(size * 3); // !!! Must Be manually freed!
verticesBuffer.put(vertex).flip();
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferData(GL_ARRAY_BUFFER, verticesBuffer, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
vertexAttrArrCount += 1;
我假设因为我为size * 3浮点数分配了缓冲区，所以它将具有该大小，并且当我将其放入VBO中时，它将分配size * 3 * 4字节，即足以容纳size * 3浮点数。
结果不对！因为我只将一个顶点（3个浮点数）放入缓冲区-它只会分配该数量的空间。因此，当我稍后尝试使用glBufferSubData时-GPU上仅可容纳3个浮点的空间，自然不会将值放在需要的地方。实际上，我感到惊讶的是它并没有完全崩溃。
要解决此问题，此刻我改为这样做：
// Vertices VBO generation
...
verticesBuffer.put(vertex).put(new float[size*3 - 3]).flip();
...
所以基本上我是手动将一个空数组放入FloatBuffer中，以确保缓冲区大小正确。
结果如下： 构造函数：
public Mesh(float[] vertex, int size)
{
texture = null;
meshType = 1; //will draw lines
FloatBuffer verticesBuffer = null;
IntBuffer indicesBuffer = null;
int vboID;
try
{
vertexCount = size;
vaoID = glGenVertexArrays();
glBindVertexArray(vaoID);
vboIDList = new ArrayList<>();
// Vertices VBO generation
vboID = glGenBuffers();
vboIDList.add(vboID);
verticesBuffer = MemoryUtil.memAllocFloat(size * 3); // !!! Must Be manually freed!
verticesBuffer.put(vertex).put(new float[size*3 - 3]).flip();
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferData(GL_ARRAY_BUFFER, verticesBuffer, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
vertexAttrArrCount += 1;
// Indices VBO generation
vboID = glGenBuffers();
vboIDList.add(vboID);
indicesBuffer = MemoryUtil.memAllocInt(size); // !!! Must be manually freed!
indicesBuffer.put(new int[size]).flip(); // I need the first element 0 anyway
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indicesBuffer, GL_STATIC_DRAW);
// unbinding
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
finally
{
if (verticesBuffer != null)
{
MemoryUtil.memFree(verticesBuffer); // Freeing vertex buffer
}
if (indicesBuffer != null)
{
MemoryUtil.memFree(indicesBuffer); // Freeing indices buffer
}
}
}
然后更新：
public void addVertex(Vector3f vertex, int position)
{
if (meshType == 1)
{
FloatBuffer subDataF = null;
IntBuffer subDataI = null;
int vboID;
lineCount = position+1;
try
{
vboID = vboIDList.get(0);
float[] vert = new float[]{vertex.x, vertex.y, vertex.z};
subDataF = MemoryUtil.memAllocFloat(vert.length); // !!! Must Be manually freed!
subDataF.put(vert).flip();
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferSubData(GL_ARRAY_BUFFER, (long)(position * 3 * 4), (FloatBuffer)subDataF);
glVertexAttribPointer(0, 3, GL_FLOAT, false, 0, 0);
vboID = vboIDList.get(1);
int[] index = new int[]{ position };
subDataI = MemoryUtil.memAllocInt(index.length); // !!! Must Be manually freed!
subDataI.put(index).flip();
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboID);
glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, (long)(position * 4), (IntBuffer)subDataI);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
finally
{
if (subDataF != null)
{
MemoryUtil.memFree(subDataF);
}
if (subDataI != null)
{
MemoryUtil.memFree(subDataI);
}
}
}
}
它有效。请注意，该代码有点脏，我在发布答案之前没有对其进行清理。