每次調用glBindBuffer時都需要glVertexAttribPointer？

Question

在OpenGL（特別是OpenGL ES 2.0）中，每次綁定一個新的VBO時，都需要調用glVertexAttribPointer？

例如：

glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer1); 

glVertexAttribPointer(ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, sizeof(vertexStruct), (void*)offsetof(vertexStruct,position)); 
glEnableVertexAttribArray(ATTRIB_POSITION); 
glVertexAttribPointer(ATTRIB_COLOR, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(vertexStruct), (void*)offsetof(vertexStruct,color); 
glEnableVertexAttribArray(ATTRIB_COLOR); 

glDrawElements(GL_TRIANGLE_STRIP, sizeof(indices)/sizeof(GLubyte), GL_UNSIGNED_BYTE, (void*)0); 

// If vertexBuffer2 has the exact same attributes as vertexBuffer1 
// is this legal or do the calls to glVertexAttribPointer (and glEnableVertexAttribArray) 
// required again? 

glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer2); 
glDrawElements(GL_TRIANGLE_STRIP, sizeof(indices)/sizeof(GLubyte), GL_UNSIGNED_BYTE, (void*)0); 

我知道有該地址不必調用glVertexAttribPointer VAOs，但我想知道如果這是確定在OpenGL辦？

Answer 1

如果你這樣做：

glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer1); 

glVertexAttribPointer(ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, sizeof(vertexStruct), (void*)offsetof(vertexStruct,position)); 
glEnableVertexAttribArray(ATTRIB_POSITION); 
glVertexAttribPointer(ATTRIB_COLOR, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(vertexStruct), (void*)offsetof(vertexStruct,color); 
glEnableVertexAttribArray(ATTRIB_COLOR); 

glBindBuffer(GL_ARRAY_BUFFER, 0); 

glDrawElements(GL_TRIANGLE_STRIP, sizeof(indices)/sizeof(GLubyte), GL_UNSIGNED_BYTE, (void*)0); 

您的代碼會工作得很好。所有gl*Pointer調用要做的是查看當函數調用時存儲在GL_ARRAY_BUFFER中的內容，並在該緩衝區和該屬性之間創建關聯。因此，更改用於屬性的緩衝區的唯一方法是調用gl*Pointer。