CODEWITHSUNDEEP
matrixglm-mathvulkan
MikeNew
MikeNew

Reputation: 121

glm::orto in Vulkan

I have simple triangle with indices:

    { { 0.0f, -0.1f } },
    { { 0.1f, 0.1f } },
    { { -0.1f, 0.1f } }

Matrix:

    ubo.model = glm::mat4(1.0f);
    ubo.view = glm::lookAt(glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));      
    ubo.proj = glm::perspective(glm::radians(45.0f), swapChainExtent.width / (float)swapChainExtent.height, 0.1f, 100.0f);      
    ubo.proj[1][1] *= -1;

This code work fine, I see triangle. But, if I try use orthographic projection:

    ubo.model = glm::mat4(1.0f);
    ubo.view = glm::lookAt(glm::vec3(0.0f, 0.0f, 1.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f)); 
    ubo.proj = glm::ortho(0.0F, swapChainExtent.width, swapChainExtent.height, 0.0F);   
    ubo.proj[1][1] *= -1;

I do not see anything. :(

I tried to googled this problem and found no solution. What's my mistake?

Update:

Solved:

    rasterizer.frontFace = VK_FRONT_FACE_CLOCKWISE;
    ...
    ubo.proj = glm::ortho(0.0F, swapChainExtent.width, swapChainExtent.height, 0.1F, 1000.0F);

Upvotes: 2

Views: 2447

Answers (1)

Ekzuzy
Ekzuzy

Reputation: 3447

First, I don't know what Z range this overload of glm::ortho produces. Maybe Your vertices don't fit in that range. There is an overload version of this function which allows You to provide a Z/depth range. Try providing a range that covers Your Z/depth values or try moving vertices further away or closer to the camera. Or provide a range like from -1000 to +1000.

And another problem. How big is Your swapchain? If it is, for example, 800 x 600 pixels then You specify rendering area in the [0, 0] to [800, 600] range (in pixels). But You provide vertices that lie in area smaller than a single pixel, in the [-0.1, -0.1] to [0.1, 0.1] range (still in pixels). It's nothing strange You don't see anything, because Your whole triangle is smaller than a single pixel.

Probably these two problems caused that You don't see anything. When You change Your depth, You don't see anything due to triangle being to small. When You change the size of Your triangle (without changing depth), object is view-frustum culled. Change the size of Your triangle and then try changing depth values of vertices.

Upvotes: 0

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