I have two objects (A and B) to be rendered using glMultiDrawArraysIndirect(). Each object has a setupBuffers() method for creating, binding a vao, then creating and binding the indirect buffer, instanced ID buffer, vertices buffer and texture coords buffer.
Here is the problem: if I call setupBuffers() of the object A before calling setupBuffers() in B, then only B will be drawn; if I call setupBuffers() of the object B before calling setupBuffers() in A, then only A will be drawn. (No exception is found.) The data stored should be all correct since I’ve tested both of them.
Object A:
protected void setupBuffers()
{
gl.glGenVertexArrays(1, vaoBuff);
gl.glBindVertexArray(vaoBuff.get(0));
gl.glGenBuffers(4, vboBuff);
//bind indirect buffer object
gl.glBindBuffer(GL4.GL_DRAW_INDIRECT_BUFFER, vboBuff.get(0));
gl.glBufferData(GL4.GL_DRAW_INDIRECT_BUFFER, instanceCount * 4 * Integer.SIZE / 8, null, GL4.GL_STATIC_DRAW);
gl.glBufferSubData(...);
//bind draw instance ID in the shader with a buffer object
gl.glBindBuffer(GL4.GL_ARRAY_BUFFER, vboBuff.get(1));
gl.glBufferData(GL4.GL_ARRAY_BUFFER, instanceCount * Integer.SIZE / 8, drawIndexBuff, GL4.GL_STATIC_DRAW);
gl.glVertexAttribIPointer(d_idLoc, 1, GL4.GL_UNSIGNED_INT, 0, 0);
gl.glVertexAttribDivisor(d_idLoc, 1);
gl.glEnableVertexAttribArray(d_idLoc);
//bind vertex data buffer object
gl.glBindBuffer(GL4.GL_ARRAY_BUFFER, vboBuff.get(2));
gl.glBufferData(GL4.GL_ARRAY_BUFFER, instanceCount * vertBuffSize * Float.SIZE / 8, null, GL4.GL_STATIC_DRAW);
gl.glBufferSubData(...);
gl.glVertexAttribPointer(verPosLoc, 3, GL4.GL_FLOAT, false, 0, 0);
gl.glEnableVertexAttribArray(verPosLoc);
//bind texture coordinate data buffer object
gl.glBindBuffer(GL4.GL_ARRAY_BUFFER, vboBuff.get(3));
gl.glBufferData(GL4.GL_ARRAY_BUFFER, instanceCount * texBuffSize * Float.SIZE / 8, null, GL4.GL_STATIC_DRAW);
gl.glBufferSubData(...);
gl.glVertexAttribPointer(tc_inLoc, 2, GL4.GL_FLOAT, false, 0, 0);
gl.glEnableVertexAttribArray(tc_inLoc);
}
drawing method in Object A:
gl.glBindVertexArray(vaoBuff.get(0));
gl.glMultiDrawArraysIndirect(GL4.GL_TRIANGLE_STRIP, 0, instanceCount, 0);
Object B:
protected void setupBuffers()
{
very similar to A…
}
drawing method in Object B:
gl.glBindVertexArray(vaoBuff.get(0));
gl.glMultiDrawArraysIndirect(GL4.GL_PATCHES, 0, instanceCount, 0);
Finally I find the problem which is at:
gl.glBindBuffer(GL4.GL_DRAW_INDIRECT_BUFFER, vboBuff.get(0));
This method used to bind a indirect buffer is called once both in Object A & B, resulting in that problem, yet I have no idea why. Any ideas about that?
