OpenGL/Webgl纹理的落后对比Vulkan的高级设计

不管是VK还剩OGL都要先创建资源，这点没啥区别，但是使用纹理的操作，就不一样了
先看看OpenGL这边使用纹理是怎么用的

glActiveTexture(GL_TEXTURE012345);
glBindTexture(GL_TEXTURE_2D, ID);
GLuint location = glGetUniformLocation(program, "nameoftexture");
glUniform1i(location , 0123456); // 0123456指的任意一个

VK这边很长，但是很清晰

VkImageView createImageView(VkImage image, VkFormat format) {
    VkImageViewCreateInfo viewInfo{};
    viewInfo.sType = VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO;
    viewInfo.image = image;
    viewInfo.viewType = VK_IMAGE_VIEW_TYPE_2D;
    viewInfo.format = format;
    viewInfo.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
    viewInfo.subresourceRange.baseMipLevel = 0;
    viewInfo.subresourceRange.levelCount = 1;
    viewInfo.subresourceRange.baseArrayLayer = 0;
    viewInfo.subresourceRange.layerCount = 1;

    VkImageView imageView;
    if (vkCreateImageView(device, &viewInfo, nullptr, &imageView) != VK_SUCCESS) {
        throw std::runtime_error("failed to create texture image view!");
    }

    return imageView;
}
VkSamplerCreateInfo samplerInfo{};
samplerInfo.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
samplerInfo.magFilter = VK_FILTER_LINEAR;
samplerInfo.minFilter = VK_FILTER_LINEAR;
省略一万字

先创建imageview samplerinfo，然后创建一个sampler布局描述，看见指定了Binding = 1

VkDescriptorSetLayoutBinding samplerLayoutBinding{};
  samplerLayoutBinding.binding = 1;
  samplerLayoutBinding.descriptorCount = 1;
  samplerLayoutBinding.descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
  samplerLayoutBinding.pImmutableSamplers = nullptr;
  samplerLayoutBinding.stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;
  
  std::array<VkDescriptorSetLayoutBinding, 2> bindings = {uboLayoutBinding, samplerLayoutBinding};
  VkDescriptorSetLayoutCreateInfo layoutInfo{};
  layoutInfo.sType = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
  layoutInfo.bindingCount = static_cast<uint32_t>(bindings.size());
  layoutInfo.pBindings = bindings.data();

然后在imageInfo的descriptor指定imageview sampler
最后把imageInfo填给type是combine的WriteDescriptorSet

for (size_t i = 0; i < MAX_FRAMES_IN_FLIGHT; i++) {
            VkDescriptorBufferInfo bufferInfo{};
            bufferInfo.buffer = uniformBuffers[i];
            bufferInfo.offset = 0;
            bufferInfo.range = sizeof(UniformBufferObject);

            VkDescriptorImageInfo imageInfo{};
            imageInfo.imageLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
            imageInfo.imageView = textureImageView;
            imageInfo.sampler = textureSampler;

            std::array<VkWriteDescriptorSet, 2> descriptorWrites{};

            descriptorWrites[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
            descriptorWrites[0].dstSet = descriptorSets[i];
            descriptorWrites[0].dstBinding = 0;
            descriptorWrites[0].dstArrayElement = 0;
            descriptorWrites[0].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER;
            descriptorWrites[0].descriptorCount = 1;
            descriptorWrites[0].pBufferInfo = &bufferInfo;

            descriptorWrites[1].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
            descriptorWrites[1].dstSet = descriptorSets[i];
            descriptorWrites[1].dstBinding = 1;
            descriptorWrites[1].dstArrayElement = 0;
            descriptorWrites[1].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
            descriptorWrites[1].descriptorCount = 1;
            descriptorWrites[1].pImageInfo = &imageInfo;

            vkUpdateDescriptorSets(device, static_cast<uint32_t>(descriptorWrites.size()), descriptorWrites.data(), 0, nullptr);
        }

然后读起来就是这个uniformbuffer知道有一个binding=1的地方有一个sampler，而他要sample的Image前面也和他绑定好了 就在VkDescriptorImageInfo里

layout(binding = 1) uniform sampler2D texSampler;

对比先激活slot，然后绑定图片，然后再去program找location,然后再把slot给uniform
这种奇怪的操作 我感觉后面这个要高级多了