3D Vertex to 2D render target co-ordinates

[Seb]

Hi, y'all,

I'm having a small problem using DirectX7.
I am creating a modeller application and use a VB form as the render target. If, for example, I render a simple primitive, such as a triangle, to the form, I want to be able to click on the primitive and then use GDI to place a 'selected' indication with node points for dragging. This works, but I find that when I cycle through the vertices of the primitive and perform manual World, View and Projection transformations (and a final 'flatten' matrix to convert using homogenous-w) the 'selected' indication is offset slightly from the original DirectX rendered primitive (i.e I end up with TWO triangles on the render target).

Does anyone have some example code (NOT Retained Mode, but Immediate Mode) to help a poor DirectX beginner obtain the correct x,y co-ordinates (i.e the same as DirectX before it is passed to the Rasterizer)?

Any help would be GREATLY appreciated!

[Zaei]

Grrr... It would be easier with DX8, there are built in functions for this =).

There might be a bug in your transformation code itself. I would also do a google search for Something along the lines of "Project D3D7 Immediate". That should turn up quite a few hits.

Good luck.

Z.

[Seb]

I'm aware that DX8 has functions for this, but since I'm using the DX7 SDK at the moment (and still getting to grips with things 3D), I wanted to have a crack with my existing set up.

I must agree that the problem must lie in the transformations I'm applying, but the matrices are pulled from the DX7 SDK help and leave me but a few pixels out in both x and y co-ords.

Hence the reason I'm searching for some example code.

Thanks for looking though!