swift - Metal Shading Language - 使用 Struct 获取缓冲区值

Question

如何使用 struct 获取缓冲区值？例如:

struct mouseInput
{
float x;
float y;
};

kernel void compute(texture2d<float, access::write> output [[texture(0)]],
                    constant float &time [[buffer(0)]],
                    constant mouseInput.x &mouseX [[buffer(1)]],///<--mouseX from swift
                    constant mouseInput.y &mouseY [[buffer(2)]],///<--mouseY from swift
                    uint2 gid [[thread_position_in_grid]]) {
...
}

然后我可以访问 mouseInput.x 等 Metal 中的任何地方。最接近的是this thread但是我不确定如何将其转化为我的用途。

Answer 1

对我来说，为鼠标位置的两个分量使用单独的缓冲区似乎很愚蠢而且很浪费。

创建一个包含两者的缓冲区。然后使用如下签名编写您的计算函数:

struct mouseInput
{
float x;
float y;
};

kernel void compute(texture2d<float, access::write> output [[texture(0)]],
                    constant float &time [[buffer(0)]],
                    constant mouseInput &mouse [[buffer(1)]],
                    uint2 gid [[thread_position_in_grid]]) {
...
}

事实上，根据您应用的其余部分，将时间与鼠标位置结合起来可能是有意义的:

struct params
{
    float time;
    float2 mouse;
};

kernel void compute(texture2d<float, access::write> output [[texture(0)]],
                    constant params &params [[buffer(0)]],
                    uint2 gid [[thread_position_in_grid]]) {
...
// use params.time to get the time value.
// Use params.mouse.x and params.mouse.y to get the mouse position.
}