我需要用新顶点更新我的网格。我这样创建了 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
}
}
}
然后我想更新 VBO 缓冲区并向其中写入新顶点。请注意，我确实创建了 VBO，以便为我的新顶点提供足够的空间，并且我确实控制它不会被填满。我还控制每次渲染调用绘制的元素数量，因此我不会绘制空的 0/0/0 顶点。
我的问题是，这段代码可以工作:
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，它会准确地绘制我需要的内容。 不过我想使用 glBufferSubData，这样我就不会在每次添加新顶点时重新分配内存。 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);
}
}
}
}
此外，我知道它没有优化我创建 floatbuffer 和 intbuffer 的方式，我只是想让它在清理之前工作。我尝试了很多事情，因此最后一段代码很奇怪。
不过，我还是不明白我做错了什么。我确实检查了我是否正确传递了所有数据，并且位置(和偏移量)似乎是按照应有的方式计算的。它只是不绘制任何东西，而当我使用 glBufferData 时它会绘制任何东西。
有人可以解释一下我在哪里犯了错误吗？
经过所有建议，这就是我最终得到的结果，但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。
最佳答案
正如我所想，这是愚蠢的事情，与 VAO 绑定(bind)等完全无关。
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 float 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 float 。
结果不是!因为我只将一个顶点(3 个浮点)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，它在 GPU 上只有 3 个 float 的空间，自然不会将这些值放在我需要的地方。事实上，我很惊讶它并没有完全崩溃。
为了解决这个问题，目前我这样做了:
// Vertices VBO generation
...
verticesBuffer.put(vertex).put(new float[size*3 - 3]).flip();
...
所以基本上我手动将一个空数组放入 FloatBuffer 中，这确保了缓冲区的大小正确。
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);
}
}
}
}
而且它有效。请注意，代码有点脏，我在发布答案之前没有清理它。
关于java - OpenGL glBufferSubData - 无法让它工作，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/57955500/