不同大小 "transfered" 的着色器存储缓冲区内容到数组缓冲区
Shader Storage Buffer contents of varying size "transfered" to Array Buffer
我在计算着色器中计算出的位置实例化一个对象。我想将包含位置的计算着色器的输出绑定到用于绘制的数组缓冲区,但我无法让它工作。我对索引算法表示歉意,我对内存对齐非常偏执并放弃了所有向量。
相关代码简化:
初始化:
//x, y, z, 1 stored in succession
/*float*/positions = new float[maxPositionCount * 4];
//initialize positions_vbo
glGenBuffers(1, &position_vbo);
glBindBuffer(GL_ARRAY_BUFFER, position_vbo);
glBindBuffer(GL_ARRAY_BUFFER, 0);
//initialize positionsOUT_ssbo
glGenBuffers(1, &positionsOUT_ssbo);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, positionsOUT_ssbo);
glBufferData(GL_SHADER_STORAGE_BUFFER, 4 * maxPositionCount * sizeof(float), NULL, GL_DYNAMIC_COPY);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 8, positionsOUT_ssbo);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, 0);
//initialize positionCounter
glGenBuffers(1, &positionCount_acb);
glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, positionCount_acb);
glBufferData(GL_ATOMIC_COUNTER_BUFFER, sizeof(GLuint), NULL, GL_DYNAMIC_DRAW);
glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 7, positionCount_acb);
glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, 0);
绘制循环:
//initialize the counter
posCount = 0;
glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 7, positionCount_acb);
glBufferSubData(GL_ATOMIC_COUNTER_BUFFER, 0, sizeof(GLuint), &posCount);
//send other data to compute shader in order to calculate positions
//dispatch and wait
//....
//retrieve the counter
glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 7, positionCount_acb);
glGetBufferSubData(GL_ATOMIC_COUNTER_BUFFER, 0, sizeof(GLuint), &positionCount_acb);
//retrieve the positions (1)
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 8, positionsOUT_ssbo);
glGetBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, posCount * 4 * sizeof(float), positions);
//bind position_vbo (2)
glBindBuffer(GL_ARRAY_BUFFER, position_vbo);
glBufferData(GL_ARRAY_BUFFER, 4 * sizeof(float) * posCount, posCount > 0 ? &positions[0] : NULL, GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
glVertexAttribDivisor(2, 1);
//instead of (1)+(2) I would like to know if something like this is possible
//glBindBuffer(GL_ARRAY_BUFFER, positionsOUT_ssbo);
//glEnableVertexAttribArray(2);
//glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
//glVertexAttribDivisor(2, 1);
//bind vertex array and draw the object instances
glBindVertexArray(vertexArrayOfTheObjectImDrawing);
glDrawElementsInstanced(GL_TRIANGLES, objectSharedVertexCount, GL_UNSIGNED_SHORT, 0, posCount);
计算着色器:
layout(local_size_x = 8, local_size_y = 8, local_size_z = 8) in;
//just in case they are relevant somehow
//can set and get them fine but they have fixed size (maxPositionCount)
//---------v
layout(std430, binding=4) buffer A {
int a[ ];
};
layout(std430, binding=5) buffer B {
int b[ ];
};
layout(std430, binding=6) buffer C {
int c1,c2,c3,c4,c5;
};
//----------^
layout(binding = 7, offset = 0) uniform atomic_uint returnedPositionsIndex;
layout(std430, binding=8) buffer pos_Out
{
float positionsOUT[ ];
};
void main()
{
ivec3 currentPos = gl_GlobalInvocationID.xyz;
if (I_want_that_position_returned(currentPos))
{
uint i = atomicCounterIncrement(returnedPositionsIndex);
positionsOUT[i * 4 + 0] = float(index3D.x);
positionsOUT[i * 4 + 1] = float(index3D.y);
positionsOUT[i * 4 + 2] = float(index3D.z);
positionsOUT[i * 4 + 3] = 1.0;
}
}
顶点着色器:
uniform mat4 worldViewProjection;
layout(location = 1) in vec4 vertPosition;
layout(location = 2) in vec4 position;
int main() {
gl_Position = worldViewProjection * (vertPosition + position);
}
目前它在
上崩溃
glGetBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, posCount * 4 * sizeof(float), positions);
调用,即使它是程序中唯一未注释的行。调试错误:
Exception thrown at 0x0000000001A132A9 (atio6axx.dll) in asd.exe:
0xC0000005: Access violation writing location 0x0000000000000000.
我已经尝试通过预先调用 glBufferData(...positions) 来初始化数据。使用正确的计数检索原子计数器。另外,有没有办法从 positionsOUT_ssbo 发送位置数据而不复制和绑定到 positions_vbo?
编辑:崩溃修复,初始化时重新声明变量"positions"..
EDIT2:我在上面评论的行确实是一种将 ssbo 的内容直接 "bind" 到数组缓冲区的方法。如果有更好的方法,欢迎分享。
Well that was embarassing. I redeclared the class variable positions in the initializing phase, shadowing the one in the draw loop. Works fine now. Thanks for pointing me in the right direction!
根据您的评论,我在下面转载了我的原始评论作为回复。
我看到你有 float* positions = new float[maxPositionCount * 4];
但我从来没有看到值实际添加到这个数组中的时间,所以据我所知它是一个未初始化的内存块。
然后您调用 glGetBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, posCount * 4 * sizeof(float), positions);
,它似乎发送了这个未初始化的内存块,它可能被设置为零,并且会解释为什么您会收到 Access violation writing location 0x0000000000000000.
错误。
我在计算着色器中计算出的位置实例化一个对象。我想将包含位置的计算着色器的输出绑定到用于绘制的数组缓冲区,但我无法让它工作。我对索引算法表示歉意,我对内存对齐非常偏执并放弃了所有向量。
相关代码简化:
初始化:
//x, y, z, 1 stored in succession
/*float*/positions = new float[maxPositionCount * 4];
//initialize positions_vbo
glGenBuffers(1, &position_vbo);
glBindBuffer(GL_ARRAY_BUFFER, position_vbo);
glBindBuffer(GL_ARRAY_BUFFER, 0);
//initialize positionsOUT_ssbo
glGenBuffers(1, &positionsOUT_ssbo);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, positionsOUT_ssbo);
glBufferData(GL_SHADER_STORAGE_BUFFER, 4 * maxPositionCount * sizeof(float), NULL, GL_DYNAMIC_COPY);
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 8, positionsOUT_ssbo);
glBindBuffer(GL_SHADER_STORAGE_BUFFER, 0);
//initialize positionCounter
glGenBuffers(1, &positionCount_acb);
glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, positionCount_acb);
glBufferData(GL_ATOMIC_COUNTER_BUFFER, sizeof(GLuint), NULL, GL_DYNAMIC_DRAW);
glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 7, positionCount_acb);
glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, 0);
绘制循环:
//initialize the counter
posCount = 0;
glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 7, positionCount_acb);
glBufferSubData(GL_ATOMIC_COUNTER_BUFFER, 0, sizeof(GLuint), &posCount);
//send other data to compute shader in order to calculate positions
//dispatch and wait
//....
//retrieve the counter
glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 7, positionCount_acb);
glGetBufferSubData(GL_ATOMIC_COUNTER_BUFFER, 0, sizeof(GLuint), &positionCount_acb);
//retrieve the positions (1)
glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 8, positionsOUT_ssbo);
glGetBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, posCount * 4 * sizeof(float), positions);
//bind position_vbo (2)
glBindBuffer(GL_ARRAY_BUFFER, position_vbo);
glBufferData(GL_ARRAY_BUFFER, 4 * sizeof(float) * posCount, posCount > 0 ? &positions[0] : NULL, GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
glVertexAttribDivisor(2, 1);
//instead of (1)+(2) I would like to know if something like this is possible
//glBindBuffer(GL_ARRAY_BUFFER, positionsOUT_ssbo);
//glEnableVertexAttribArray(2);
//glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
//glVertexAttribDivisor(2, 1);
//bind vertex array and draw the object instances
glBindVertexArray(vertexArrayOfTheObjectImDrawing);
glDrawElementsInstanced(GL_TRIANGLES, objectSharedVertexCount, GL_UNSIGNED_SHORT, 0, posCount);
计算着色器:
layout(local_size_x = 8, local_size_y = 8, local_size_z = 8) in;
//just in case they are relevant somehow
//can set and get them fine but they have fixed size (maxPositionCount)
//---------v
layout(std430, binding=4) buffer A {
int a[ ];
};
layout(std430, binding=5) buffer B {
int b[ ];
};
layout(std430, binding=6) buffer C {
int c1,c2,c3,c4,c5;
};
//----------^
layout(binding = 7, offset = 0) uniform atomic_uint returnedPositionsIndex;
layout(std430, binding=8) buffer pos_Out
{
float positionsOUT[ ];
};
void main()
{
ivec3 currentPos = gl_GlobalInvocationID.xyz;
if (I_want_that_position_returned(currentPos))
{
uint i = atomicCounterIncrement(returnedPositionsIndex);
positionsOUT[i * 4 + 0] = float(index3D.x);
positionsOUT[i * 4 + 1] = float(index3D.y);
positionsOUT[i * 4 + 2] = float(index3D.z);
positionsOUT[i * 4 + 3] = 1.0;
}
}
顶点着色器:
uniform mat4 worldViewProjection;
layout(location = 1) in vec4 vertPosition;
layout(location = 2) in vec4 position;
int main() {
gl_Position = worldViewProjection * (vertPosition + position);
}
目前它在
上崩溃glGetBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, posCount * 4 * sizeof(float), positions);
调用,即使它是程序中唯一未注释的行。调试错误:
Exception thrown at 0x0000000001A132A9 (atio6axx.dll) in asd.exe:
0xC0000005: Access violation writing location 0x0000000000000000.
我已经尝试通过预先调用 glBufferData(...positions) 来初始化数据。使用正确的计数检索原子计数器。另外,有没有办法从 positionsOUT_ssbo 发送位置数据而不复制和绑定到 positions_vbo?
编辑:崩溃修复,初始化时重新声明变量"positions"..
EDIT2:我在上面评论的行确实是一种将 ssbo 的内容直接 "bind" 到数组缓冲区的方法。如果有更好的方法,欢迎分享。
Well that was embarassing. I redeclared the class variable positions in the initializing phase, shadowing the one in the draw loop. Works fine now. Thanks for pointing me in the right direction!
根据您的评论,我在下面转载了我的原始评论作为回复。
我看到你有 float* positions = new float[maxPositionCount * 4];
但我从来没有看到值实际添加到这个数组中的时间,所以据我所知它是一个未初始化的内存块。
然后您调用 glGetBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, posCount * 4 * sizeof(float), positions);
,它似乎发送了这个未初始化的内存块,它可能被设置为零,并且会解释为什么您会收到 Access violation writing location 0x0000000000000000.
错误。