Vulkan: Loading floating point cubemap textures distorted - vulkan

Question

I am using vulkan-tutorial codes and i made modify for cubemap.
when i use VK_FORMAT_R8G8B8A8_UNORM is working with this code:
unsigned char* pixelsArray[6];
for (int i = 0; i < 6; ++i)
{
pixelsArray[i] = stbi_load(imageFileArray[i].c_str(), &texWidth, &texHeight, &texChannels, STBI_rgb_alpha);
}
VkDeviceSize allSize = texWidth * texHeight * 4 * 6;
VkDeviceSize size = texWidth * texHeight * 4 ;
VkBufferCreateInfo bufferInfo{};
...
bufferInfo.size = allSize ;
vkMapMemory(device, stagingBufferMemory, 0, AllSize, 0, &data);
for(int i = 0; i < 6; ++i)
{
memcpy( (char*) data + (size*i) , pixelsArray[i], static_cast<size_t>(size));
}
vkUnmapMemory(device, stagingBufferMemory);
VkImageCreateInfo imageInfo{};
...
imageInfo.arrayLayers = 6;
imageInfo.format = VK_FORMAT_R8G8B8A8_UNORM;
imageInfo.flags = VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT;
VkImageViewCreateInfo viewInfo{};
...
viewInfo.viewType = VK_IMAGE_VIEW_TYPE_CUBE;
viewInfo.format = VK_FORMAT_R8G8B8A8_UNORM;
viewInfo.subresourceRange.layerCount = 6;
but when i try VK_FORMAT_R16G16B16A16_SFLOAT is giving distorted display and no validation error with this code:
float* pixelsArray[6];
for (int i = 0; i < 6; ++i)
{
pixelsArray[i] = stbi_loadf(imageFileArray[i].c_str(), &texWidth, &texHeight, &texChannels, STBI_rgb_alpha);
}
VkDeviceSize allSize = texWidth * texHeight * 4 * 6 * 2;// I added *2
VkDeviceSize size = texWidth * texHeight * 4 * 2;// I added *2
VkBufferCreateInfo bufferInfo{};
...
bufferInfo.size = allSize ;
vkMapMemory(device, stagingBufferMemory, 0, AllSize, 0, &data);
for(int i = 0; i < 6; ++i)
{
memcpy( (char*) data + (size*i) , pixelsArray[i], static_cast<size_t>(size));
}
vkUnmapMemory(device, stagingBufferMemory);
VkImageCreateInfo imageInfo{};
...
imageInfo.arrayLayers = 6;
imageInfo.format = VK_FORMAT_R16G16B16A16_SFLOAT;
imageInfo.flags = VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT;
VkImageViewCreateInfo viewInfo{};
...
viewInfo.viewType = VK_IMAGE_VIEW_TYPE_CUBE;
viewInfo.format = VK_FORMAT_R16G16B16A16_SFLOAT;
viewInfo.subresourceRange.layerCount = 6;
when VK_FORMAT_R8G8B8A8_UNORM :
when VK_FORMAT_R16G16B16A16_SFLOAT :

Answer 1

i fixed the problem. problem was that i want to use half float but i was sending float to memcpy function.i searched how can i use half float and i found a solution without using extra library.
what i did add helper functions :
typedef unsigned int uint;
typedef unsigned short ushort;
uint as_uint(const float x)
{
return *(uint*)&x;
}
ushort float_to_half(const float x)
{
// IEEE-754 16-bit floating-point format (without infinity): 1-5-10, exp-15, +-131008.0, +-6.1035156E-5, +-5.9604645E-8, 3.311 digits
const uint b = as_uint(x)+0x00001000; // round-to-nearest-even: add last bit after truncated mantissa
const uint e = (b&0x7F800000)>>23; // exponent
const uint m = b&0x007FFFFF; // mantissa; in line below: 0x007FF000 = 0x00800000-0x00001000 = decimal indicator flag - initial rounding
return (b&0x80000000)>>16 | (e>112)*((((e-112)<<10)&0x7C00)|m>>13) | ((e<113)&(e>101))*((((0x007FF000+m)>>(125-e))+1)>>1) | (e>143)*0x7FFF; // sign : normalized : denormalized : saturate
}
and fix problem with this helper functions :
VkDeviceSize size_2 = texWidth * texHeight * 4;// different from the above variables in question : allSize or size
//create half float for cubemap
void* half_pixelsArray[6];
half_pixelsArray[0] = new ushort[size_2];
half_pixelsArray[1] = new ushort[size_2];
half_pixelsArray[2] = new ushort[size_2];
half_pixelsArray[3] = new ushort[size_2];
half_pixelsArray[4] = new ushort[size_2];
half_pixelsArray[5] = new ushort[size_2];
//copy from float to half float
for (int i = 0; i < 6; ++i)
{
for (int j = 0; j < size_2; ++j)
{
((ushort*)half_pixelsArray[i])[j] = float_to_half( pixelsArray[i][j] );
}
}
// and change float to half flaot in memcpy
memcpy( (char*) data + (layerSize*i) , half_pixelsArray[i], static_cast<size_t>(layerSize));