A Simple question

[siberianstar]

How can i see if a triangle S3DVertex2TCoords triangle[3], is interesecting the frustum view?

[vitek]

Code: Select all

// this is a rough estimate because the frustrum box is larger than the actual view frustrum
core::aabbox3df frustrumBox = SceneManager->getActiveCamera()->getViewFrustrum()->getBoundingBox();

const core::line3df lineA(triangles[0].Pos, triangles[1].Pos);
const core::line3df lineB(triangles[1].Pos, triangles[2].Pos);
const core::line3df lineC(triangles[2].Pos, triangles[0].Pos);

return frustrumBox.intersectsWithLine(lineA) ||
       frustrumBox.intersectsWithLine(lineB) ||
       frustrumBox.intersectsWithLine(lineC);

Code: Select all

// this is even worse estimate because the triangle is fit into a box and that
// is compared against the frustrum box
core::aabbox3df frustrumBox = SceneManager->getActiveCamera()->getViewFrustrum()->getBoundingBox();

core::aabbox3df triangleBox(triangles[0].Pos);
triangleBox.addInternalPoint(triangles[1].Pos);
triangleBox.addInternalPoint(triangles[2].Pos);

return frustrumBox.intersectsWithBox(triangleBox);

Code: Select all

// this should be more accurate, but slow. probably a more efficient way
scene::SViewFrustrum* frustrum =  SceneManager->getActiveCamera()->getViewFrustrum();

const core::line3df lineA(triangles[0].Pos, triangles[1].Pos);
const core::line3df lineB(triangles[1].Pos, triangles[2].Pos);
const core::line3df lineC(triangles[2].Pos, triangles[0].Pos);

u32 p;
for (p = 0; p < scene::VF_PLANE_COUNT; ++p)
{
  if (frustrum->planes[p].getIntersectionWithLimitedLine(triangles[0].Pos, triangles[1].Pos) ||
      frustrum->planes[p].getIntersectionWithLimitedLine(triangles[1].Pos, triangles[2].Pos) ||
      frustrum->planes[p].getIntersectionWithLimitedLine(triangles[2].Pos, triangles[0].Pos))
    return true;
}

return false;

[siberianstar]

i've to put the code on COpenGLDriver.cpp, what i've to include ? the last code you paste me didn't compile

[vitek]

Dude, you don't want to be putting that code in the driver. There are better ways to do what you want.

[siberianstar]

i've to tessellate the triangles that intersect the frustrum view planes on rendering time..

[bitplane]

software2 driver does this, you can find the code in there.
also, why would you need to do this anyway?

[siberianstar]

i've rewritten the csoftwaredriver2 class because there were less code to delete I'm using pspgl with the PSP Console to port irrlicht 1.0 on psp.

But the psp has got a stupid clipping algo and when a vertex goes too far from the screen it just culls the entire primitive. The result is here:

http://85.25.18.122/IM000345.jpg

[siberianstar]

I've rewritten the csoftwaredriver2 class because there were less code to delete. I'm using PSPGL to port Irrlicht 1.0 on the PSP. But the PSP has a stupid clip algo. And when a vertex goes too far away from the screen the psp just cull the entire primitive.

Result:
http://85.25.18.122/IM000345.jpg

So i'had to tessellate the triangles that intersect the frustum view.