Plan for Doyoon Kim

Ok, I started experimenting with adding grass (or little shrubs) to Torque. This is just one way from my tests, so I don't want to stop anyone else from doing grass (melv and phil :).

Here's the scene with no grass:
No grass test
Now with some grass:
1 grass per triangle
grass test1
20 grass per triangle
grass test2
50
grass test3
100
grass test4
200
grass test6

Each grass blade is individually rendered as a single translucent opengl triangle. Here's how. All grass rendering is done in TerrainRender::renderBlock(). It goes through each triangle and finds any number of random points within the triangle to represent each grass blade. Finding a random point within a triangle is simple:

for (U32 i = 0; i < gTerrainGrassPerTriangle; i++) {
// lets find a random point within polygon (triangle)
F32 x = sgRandom.randF(0.0, 1.0);
F32 y = sgRandom.randF(0.0, 1.0);
F32 z;
if (x+y > 1.0) {
x = 1 - x;
y = 1 - y;
}
z = 1 - x - y;

GrassPoint randPoint;
randPoint.x = (x * point1.x) + (y * point2.x) + (z * point3.x);
randPoint.y = (x * point1.y) + (y * point2.y) + (z * point3.y);
randPoint.z = (x * point1.z) + (y * point2.z) + (z * point3.z);

Now that we have a random point, we store it in an array of grass points that we render later. For the random seed, I just use the IndexCount of the triangle strip so it'll select the same set of random points every time. There are lots of problems though such as with sorting (mine aren't yet), speed, and depth buffer issues. Another problem is that it effects the whole terrain globally.

Also, looping through every triangle in the terrain is too much so I also test the terrain chunk (square) distance to flag each chunk to render grass or not (same way detail textures are handled for terrain).

And the code isn't optimized. It just spits out opengl vertices for every grass blade.

Here are some more test shots:

Textured triangle
textured grass test1
Grass option dialog box, settings can be changed in real time
textured grass test2

Textured alpha blended quad:
quad test1
If I set the detail levels low, I can get decent frame rates
quad test2

Overkill test shots:
200 grass blades per triangle
overkill test 1
High grass stress test1
overkill test 2
High grass stress test2
overkill test 3

All shots were taken on an Athlon 1800+ XP and Geforce 1 card. If I ever get anywhere with it, I'll post the code.