From 8ceed6bfe80297b03019316d3880f9b77d31b4e7 Mon Sep 17 00:00:00 2001
From: Allanis <allanis.saracraft.studios@gmail.com>
Date: Sat, 23 Dec 2017 19:27:31 +0000
Subject: [PATCH] [Add] Preliminary atmospheres.

---
 src/planet.cpp | 113 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/planet.h   |   1 +
 2 files changed, 114 insertions(+)

diff --git a/src/planet.cpp b/src/planet.cpp
index 910dbc6..d6f6bef 100644
--- a/src/planet.cpp
+++ b/src/planet.cpp
@@ -592,6 +592,7 @@ void Planet::DrawRockyPlanet(void) {
   float col[4], col2[4];
   //MTRand rng((int)L3D::GetGameTime());
   MTRand rng(sbody.seed);
+  float darkblue[4] = { .05, .05, .2, 1 };
   float blue[4]   = { .2, .2, 1, 1 };
   float green[4]  = { .2, .8, .2, 1 };
   float white[4]  = { 1, 1, 1, 1 };
@@ -601,6 +602,7 @@ void Planet::DrawRockyPlanet(void) {
 
   switch(sbody.type) {
   case StarSystem::TYPE_PLANET_DWARF:
+  case StarSystem::TYPE_PLANET_SMALL:
     barrenBodyCol.GenCol(col2, rng);
     SetMaterialColor(col2);
     DrawLovelyRoundCube(1.0f);
@@ -644,6 +646,27 @@ void Planet::DrawRockyPlanet(void) {
       glPopMatrix();
     }
     break;
+
+  case StarSystem::TYPE_PLANET_WATER:
+  case StarSystem::TYPE_PLANET_WATER_THICK_ATMOS:
+    SetMaterialColor(darkblue);
+    DrawLovelyRoundCube(1.0f);
+
+    n = rng.Int32(3, 10);
+    while(n--) {
+      barrenBodyCol.GenCol(col2, rng);
+      SetMaterialColor(col2);
+      rot = matrix4x4d::RotateXMatrix(-M_PI/2+rng.Double(-M_PI/3, M_PI/3));
+      rot.RotateZ(rng.Double(M_PI*2));
+      MakeContinent(rot, rng.Double(0.1, 0.5), rng);
+    }
+    /* Poles. */
+    SetMaterialColor(white);
+    rot = matrix4x4d::Identity();
+    MakeContinent(rot, 0.25, rng);
+    rot = matrix4x4d::RotateXMatrix(M_PI);
+    MakeContinent(rot, 0.25, rng);
+    break;
   case StarSystem::TYPE_PLANET_INDIGENOUS_LIFE:
     SetMaterialColor(blue);
     DrawLovelyRoundCube(1.0f);
@@ -719,6 +742,91 @@ void Planet::DrawGasGiant(void) {
   }
 }
 
+static void _DrawAtmosphere(double rad1, double rad2, vector3d& pos, const float col[4]) {
+  glPushMatrix();
+  /* Face the camera damn you! */
+  vector3d zaxis = vector3d::Normalize(-pos);
+  vector3d xaxis = vector3d::Normalize(vector3d::Cross(zaxis, vector3d(0, 1, 0)));
+  vector3d yaxis = vector3d::Cross(zaxis, xaxis);
+  matrix4x4d rot = matrix4x4d::MakeRotMatrix(xaxis, yaxis, zaxis).InverseOf();
+  glMultMatrixd(&rot[0]);
+
+  const double angStep = M_PI/32;
+  /* Find angle player -> center -> tangent point. */
+  /* Tangent is from player to surface of sphere. */
+  float tanAng = acos(rad1 / pos.Length());
+
+  /* Then we can put the atmosphere on the horizon. */
+  vector3d r1(0.0, 0.0, rad1);
+  vector3d r2(0.0, 0.0, rad2);
+  rot = matrix4x4d::RotateYMatrix(tanAng);
+  r1 = rot*r1;
+  r2 = rot*r2;
+
+  rot = matrix4x4d::RotateZMatrix(angStep);
+
+  glDisable(GL_LIGHTING);
+  glEnable(GL_BLEND);
+  glDisable(GL_CULL_FACE);
+  glBegin(GL_TRIANGLE_STRIP);
+    for(float ang = 0; ang < 2*M_PI; ang += angStep) {
+      glColor4fv(col);
+      glVertex3dv(&r1.x);
+      glColor4f(0,0,0,0);
+      glVertex4dv(&r2.x);
+      r1 = rot*r1;
+      r2 = rot*r2;
+    }
+    glColor4fv(col);
+    glVertex3dv(&r1.x);
+    glColor4f(0,0,0,0);
+    glVertex3dv(&r2.x);
+  glEnd();
+  glEnable(GL_CULL_FACE);
+  glDisable(GL_BLEND);
+  glEnable(GL_LIGHTING);
+  glPopMatrix();
+}
+
+void Planet::DrawAtmosphere(double rad, vector3d& pos) {
+  if(sbody.type == StarSystem::TYPE_PLANET_SMALL) {
+    const float c[4] = { .2, .2, .3, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.05, pos, c);
+  }
+  else if(sbody.type == StarSystem::TYPE_PLANET_CO2_THICK_ATMOS) {
+    const float c[4] = { .8, .8, .8, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.1, pos, c);
+  }
+  else if(sbody.type == StarSystem::TYPE_PLANET_CO2) {
+    const float c[4] = { .5, .5, .5, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.05, pos, c);
+  }
+  else if(sbody.type == StarSystem::TYPE_PLANET_METHANE_THICK_ATMOS) {
+    const float c[4] = { .2, .6, .3, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.1, pos, c);
+  }
+  else if(sbody.type == StarSystem::TYPE_PLANET_METHANE) {
+    const float c[4] = { .2, .6, .3, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.05, pos, c);
+  }
+  else if(sbody.type == StarSystem::TYPE_PLANET_HIGHLY_VOLCANIC) {
+    const float c[4] = { .5, .2, .2, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.05, pos, c);
+  }
+  else if(sbody.type == StarSystem::TYPE_PLANET_WATER_THICK_ATMOS) {
+    const float c[4] = { .8, .8, .8, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.1, pos, c);
+  }
+  else if(sbody.type == StarSystem::TYPE_PLANET_WATER) {
+    const float c[4] = { .2, .2, .4, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.05, pos, c);
+  }
+  else if(sbody.type == StarSystem::TYPE_PLANET_INDIGENOUS_LIFE) {
+    const float c[4] = { .2, .2, .5, .8 };
+    _DrawAtmosphere(rad*0.99, rad*1.05, pos, c);
+  }
+}
+
 void Planet::Render(const Frame* a_camFrame) {
   glPushMatrix();
 
@@ -760,8 +868,13 @@ void Planet::Render(const Frame* a_camFrame) {
       }
       glEndList();
     }
+    glPushMatrix();
     glScalef(rad, rad, rad);
     glCallList(crudDList);
+    glPopMatrix();
+
+    DrawAtmosphere(rad, fpos);
+
     glClear(GL_DEPTH_BUFFER_BIT);
   }
   glPopMatrix();
diff --git a/src/planet.h b/src/planet.h
index af7f937..f718aa1 100644
--- a/src/planet.h
+++ b/src/planet.h
@@ -17,6 +17,7 @@ public:
 private:
   void DrawRockyPlanet(void);
   void DrawGasGiant(void);
+  void DrawAtmosphere(double rad, vector3d& pos);
 
   vector3d pos;
   dGeomID geom;