为什么调用 glMultiDrawElementsIndirect 时会出现错误 INVALID_OPERATION

Question

我目前正尝试在 Java 中将 glMultiDrawElementsIndirect 与 LWJGL 一起使用，但出现错误 INVALID_OPERATION。

glMultiDrawElementsIndirect(GL_TRIANGLES,  GL_UNSIGNED_INT, this.modelManager.indirect, NB_TYPE_MESH, 0);

我在文档中看到此错误与 GL_DRAW_INDIRECT_BUFFER 或 GL_ELEMENT_ARRAY_BUFFER 有关，但我不知道问题出在我的代码中。

间接缓冲区

int[] indirect = new int[NB_TYPE_MESH*5];
for(int i=0; i<2; i++) {
    indirect[i] = getElementCount().get(i);
    indirect[1+i] = Game.NB_MAX_OBJECTS/2;
    indirect[2+i] = 0;
    indirect[3+i] = i==0?0:getElementCount().get(i-1);
    indirect[4+i] = i; // maybe 0
}
vboIdIndirect = glGenBuffers();
IntBuffer gIndirectBuffer = MemoryUtil.memAllocInt(indirect.length);
gIndirectBuffer.put(indirect).flip();
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, vboIdIndirect);
glBufferData(GL_DRAW_INDIRECT_BUFFER, gIndirectBuffer, GL_DYNAMIC_DRAW);

我的元素缓冲区

vboId = glGenBuffers();
vboIdList.add(vboId);
indicesBuffer = MemoryUtil.memAllocInt(indices.length);
indicesBuffer.put(indices).flip();

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vboId);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indicesBuffer, GL_DYNAMIC_DRAW);

indices 包含 NB_TYPE_MESH 类型网格的索引

Answer 1

如果在调用 glMultiDrawElementsIndirect 时将缓冲区绑定到目标 GL_DRAW_INDIRECT_BUFFER，则 indirect 参数被解释为基本机器单位中的偏移量这个缓冲区。

因此您需要在绘制元素之前绑定 GL_DRAW_INDIRECT_BUFFER，但是 indirect 参数必须是 null:

~~glMultiDrawElementsIndirect(GL_TRIANGLES, GL_UNSIGNED_INT, this.modelManager.indirect, NB_TYPE_MESH, 0);~~

glBindBuffer(GL_DRAW_INDIRECT_BUFFER, vboIdIndirect);
glMultiDrawElementsIndirect(GL_TRIANGLES,  GL_UNSIGNED_INT, null, NB_TYPE_MESH, 0);

另见 Java Code Examples glMultiDrawElementsIndirect()

为什么调用 glMultiDrawElementsIndirect 时会出现错误 INVALID_OPERATION

Why do I get error INVALID_OPERATION when I call glMultiDrawElementsIndirect

java

opengl

lwjgl