Drawing cube in SharpDX, wrong perspective

Question

I want to draw a cube. This is what i currently have:

As you can see, the perspective is VERY wrong. The the size in the z-direction is too small and the difference between the front and back size is wrong.

My code:

worldprojMatrix = Matrix.Identity;
worldprojMatrix *= Matrix.Translation(0, 0, 10);
//float ratio = ScreenWidth/ScreenHeight;
worldprojMatrix *= Matrix.PerspectiveFovLH(1f, ratio, 1f, 100f);
//worldprojMatrix *= Matrix.RotationY(1.3f);

worldprojMatrix.Transpose();

//update the matrix with a constant buffer
DeviceContext.UpdateSubresource(ref worldprojMatrix, worldprojBuffer);

Vertex Shader:

struct VOut
{
  float4 position : SV_POSITION;
  float4 color    : COLOR;
};

cbuffer meshBuffer  :  register(b1)
{
  float4x4 worldprojMatrix;
}

VOut VShader(float4 position : POSITION, float4 color : COLOR)
{
  VOut output;

  output.position = mul(position, worldprojMatrix);
  output.color = color;

  return output;
}

I tried an ortho perspective, but there is the same problem: the z dimension is too small.

How can i fix that?

Answer 1

I don't know what vertex data you're using to draw that, but supposing it is a cube, I wouldn't say that the perspective is VERY wrong, or even wrong at all, on the left picture.

Based on your commented-out code, your ultimate view-projection matrix is getting calculated like this:

identity * translation * projection * rotation

Your drawing is getting distorted because you're rotating after applying the perspective matrix. Your view-projection matrix should be more like:

identity * rotation * translation * projection

Remember that matrix multiplication is not commutative.

Answer 2

OpenGL uses Right Handed coordinate system. But you are using Matrix.PerspectiveFovLH which creates a Left Handed perspective matrix. That is probably what causes the error.