void CGrassDrawer::CreateGrassDispList(int listNum)
{
CVertexArray* va = GetVertexArray();
va->Initialize();
rng.Seed(15);
for (int a = 0; a < strawPerTurf; ++a) {
// draw a single blade
const float lngRnd = rng.RandFloat();
const float length = mapInfo->grass.bladeHeight * (1.0f + lngRnd);
const float maxAng = mapInfo->grass.bladeAngle * std::max(rng.RandFloat(), 1.f - smoothstep(0.f,1.f,lngRnd));
float3 sideVect(rng.RandFloat() - 0.5f, 0.0f, rng.RandFloat() - 0.5f);
sideVect.ANormalize();
float3 bendVect = sideVect.cross(UpVector); // direction to bend into
sideVect *= mapInfo->grass.bladeWidth * (-0.15f * lngRnd + 1.0f);
const float3 basePos = rng.RandVector2D() * (turfSize - (bendVect * std::sin(maxAng) * length).Length2D());
// select one of the 16 color shadings
const float xtexCoord = (rng.RandInt() % 16) / 16.0f;
const int numSections = 2 + int(maxAng * 1.2f + length * 0.2f);
float3 normalBend = -bendVect;
// start btm
va->AddVertexTN(basePos + sideVect - float3(0.0f, 3.0f, 0.0f), xtexCoord , 0.f, normalBend);
va->AddVertexTN(basePos - sideVect - float3(0.0f, 3.0f, 0.0f), xtexCoord + (1.0f / 16), 0.f, normalBend);
for (float h = 0.0f; h < 1.0f; h += (1.0f / numSections)) {
const float ang = maxAng * h;
const float3 n = (normalBend * std::cos(ang) + UpVector * std::sin(ang)).ANormalize();
const float3 edgePos = (UpVector * std::cos(ang) + bendVect * std::sin(ang)) * length * h;
const float3 edgePosL = edgePos - sideVect * (1.0f - h);
const float3 edgePosR = edgePos + sideVect * (1.0f - h);
va->AddVertexTN(basePos + edgePosR, xtexCoord + (1.0f / 32) * h , h, (n + sideVect * 0.04f).ANormalize());
va->AddVertexTN(basePos + edgePosL, xtexCoord - (1.0f / 32) * h + (1.0f / 16), h, (n - sideVect * 0.04f).ANormalize());
}
// end top tip (single triangle)
const float3 edgePos = (UpVector * std::cos(maxAng) + bendVect * std::sin(maxAng)) * length;
const float3 n = (normalBend * std::cos(maxAng) + UpVector * std::sin(maxAng)).ANormalize();
va->AddVertexTN(basePos + edgePos, xtexCoord + (1.0f / 32), 1.0f, n);
// next blade
va->EndStrip();
}
glNewList(listNum, GL_COMPILE);
va->DrawArrayTN(GL_TRIANGLE_STRIP);
glEndList();
}
void CGrassDrawer::CreateGrassDispList(int listNum)
{
CVertexArray* va = GetVertexArray();
va->Initialize();
for (int a = 0; a < strawPerTurf; ++a) {
const float maxAng = mapInfo->grass.bladeAngle * rng.RandFloat();
const float length = mapInfo->grass.bladeHeight + mapInfo->grass.bladeHeight * rng.RandFloat();
float3 sideVect(rng.RandFloat() - 0.5f, 0.0f, rng.RandFloat() - 0.5f);
sideVect.ANormalize();
float3 forwardVect = sideVect.cross(UpVector);
sideVect *= mapInfo->grass.bladeWidth;
float3 basePos(30.0f, 0.0f, 30.0f);
while (basePos.SqLength2D() > (turfSize * turfSize / 4)) {
basePos = float3(rng.RandFloat() - 0.5f, 0.f, rng.RandFloat() - 0.5f) * turfSize;
}
const float xtexCoord = int(14.9999f * rng.RandFloat()) / 16.0f;
const int numSections = 1 + int(maxAng * 5.0f);
// draw single blade
for (float h = 0; h <= 1.0f; h += (1.0f / numSections)) {
const float ang = maxAng * h;
const float3 edgePos = (UpVector * std::cos(ang) + forwardVect * std::sin(ang)) * length * h;
const float3 edgePosL = edgePos - sideVect * (1.0f - h);
const float3 edgePosR = edgePos + sideVect * (1.0f - h);
if (h == 0.0f) {
// start with a degenerated triangle
va->AddVertexT(basePos + edgePosR - float3(0.0f, 0.1f, 0.0f), xtexCoord, h);
va->AddVertexT(basePos + edgePosR - float3(0.0f, 0.1f, 0.0f), xtexCoord, h);
} else {
va->AddVertexT(basePos + edgePosR, xtexCoord, h);
}
va->AddVertexT(basePos + edgePosL, xtexCoord + (1.0f / 16), h);
}
// end with a degenerated triangle
// -> this way we can render multiple blades in a single GL_TRIANGLE_STRIP
const float3 edgePos = (UpVector * std::cos(maxAng) + forwardVect * std::sin(maxAng)) * length;
va->AddVertexT(basePos + edgePos, xtexCoord + (1.0f / 32), 1.0f);
va->AddVertexT(basePos + edgePos, xtexCoord + (1.0f / 32), 1.0f);
}
glNewList(listNum, GL_COMPILE);
va->DrawArrayT(GL_TRIANGLE_STRIP);
glEndList();
}
