Vulkan vertex drawing order

user_9369168 0
Viewed 91

I am currently getting into vulkan and am now at the point where I want to draw a qube with perspective projection. But the drawing order of the faces doesnt seem to woek right.

qube

This is the depth stencil info of my pipeline

const auto depth_stencil_state_create_info = VkPipelineDepthStencilStateCreateInfo{
      .sType = VK_STRUCTURE_TYPE_PIPELINE_DEPTH_STENCIL_STATE_CREATE_INFO,
      .pNext = nullptr,
      .flags = 0,
      .depthTestEnable = true,
      .depthWriteEnable = true,
      .depthCompareOp = VK_COMPARE_OP_LESS,
      .depthBoundsTestEnable = false,
      .stencilTestEnable = false,
      .front = VkStencilOpState{},
      .back = VkStencilOpState{},
      .minDepthBounds = 0.0f,
      .maxDepthBounds = 1.0f
    };

And the rasterization into

const auto rasterization_stage_create_info = VkPipelineRasterizationStateCreateInfo {
      .sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO,
      .pNext = nullptr,
      .flags = 0,
      .depthClampEnable = false,
      .rasterizerDiscardEnable = false,
      .polygonMode = VK_POLYGON_MODE_FILL,
      .cullMode = VK_CULL_MODE_NONE,
      .frontFace = VK_FRONT_FACE_CLOCKWISE,
      .depthBiasEnable = false,
      .depthBiasConstantFactor = 0.0f,
      .depthBiasClamp = 0.0f,
      .depthBiasSlopeFactor = 0.0f,
      .lineWidth = 1.0f
    };

I am using a vertex struct with a glm::vec3 for position and color.

Those are my vertices

const auto vertices = std::vector<vertex>{
      // left face (white)
      {{-.5f, -.5f, -.5f}, {.9f, .9f, .9f}},
      {{-.5f, .5f, .5f}, {.9f, .9f, .9f}},
      {{-.5f, -.5f, .5f}, {.9f, .9f, .9f}},
      {{-.5f, .5f, -.5f}, {.9f, .9f, .9f}},
 
      // right face (yellow)
      {{.5f, -.5f, -.5f}, {.8f, .8f, .1f}},
      {{.5f, .5f, .5f}, {.8f, .8f, .1f}},
      {{.5f, -.5f, .5f}, {.8f, .8f, .1f}},
      {{.5f, .5f, -.5f}, {.8f, .8f, .1f}},
 
      // top face (orange, remember y axis points down)
      {{-.5f, -.5f, -.5f}, {.9f, .6f, .1f}},
      {{.5f, -.5f, .5f}, {.9f, .6f, .1f}},
      {{-.5f, -.5f, .5f}, {.9f, .6f, .1f}},
      {{.5f, -.5f, -.5f}, {.9f, .6f, .1f}},
 
      // bottom face (red)
      {{-.5f, .5f, -.5f}, {.8f, .1f, .1f}},
      {{.5f, .5f, .5f}, {.8f, .1f, .1f}},
      {{-.5f, .5f, .5f}, {.8f, .1f, .1f}},
      {{.5f, .5f, -.5f}, {.8f, .1f, .1f}},
 
      // nose face (blue)
      {{-.5f, -.5f, 0.5f}, {.1f, .1f, .8f}},
      {{.5f, .5f, 0.5f}, {.1f, .1f, .8f}},
      {{-.5f, .5f, 0.5f}, {.1f, .1f, .8f}},
      {{.5f, -.5f, 0.5f}, {.1f, .1f, .8f}},
 
      // tail face (green)
      {{-.5f, -.5f, -0.5f}, {.1f, .8f, .1f}},
      {{.5f, .5f, -0.5f}, {.1f, .8f, .1f}},
      {{-.5f, .5f, -0.5f}, {.1f, .8f, .1f}},
      {{.5f, -.5f, -0.5f}, {.1f, .8f, .1f}}
    };

And my indices

const auto indices = std::vector<sbx::uint32>{
      0,  1,  2,
      0,  3,  1,
      4,  5,  6,
      4,  7,  5,
      8,  9,  10,
      8,  11, 9,
      12, 13, 14, 
      12, 15, 13, 
      16, 17, 18,
      16, 19, 17,
      20, 21, 22,
      20, 23, 21
    };

Do you have any idears or hints where I sould look to solve this behaviour? Has this even to do with the pipeline or am I on the wrong path?

Edit: Might that be a problem caused by vulkans coordiante system? And if so, how would I fix it?

vulkan c++
1 Answers

Your problem has nothing to do with vertex order since you're not culling backfaces:

  .cullMode = VK_CULL_MODE_NONE,

If you're trying to avoid setting up a depth test by just drawing front faces, you need to change this to

  .cullMode = VK_CULL_MODE_BACK_BIT,

and then you'll either be able to see only the front faces, and won't have this overlapping issue. However, if your triangle winding is incorrect, the cube will look inverted.

user_853060
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