Merge pull request colobot#1022 from immibis/dev

Fix horizontal scrolling of planets and background images

src/graphics/engine/engine.cpp

@@ -2631,6 +2631,10 @@ void CEngine::SetFocus(float focus)
     float farPlane = m_deepView[0] * m_clippingDistance;
 
     float aspect = static_cast<float>(m_size.x) / static_cast<float>(m_size.y);
+
+    // Compute H-FoV from V-FoV and aspect ratio.
+    m_hfov = 2.0f * atan(aspect * tan(focus / 2.0f));
+
     Math::LoadProjectionMatrix(m_matProj, m_focus, aspect, 0.5f, farPlane);
 }
 
@@ -2639,6 +2643,16 @@ float CEngine::GetFocus()
     return m_focus;
 }
 
+float CEngine::GetVFovAngle()
+{
+    return m_focus;
+}
+
+float CEngine::GetHFovAngle()
+{
+    return m_hfov;
+}
+
 void CEngine::SetShadowColor(float value)
 {
     m_shadowColor = value;
@@ -4727,8 +4741,9 @@ void CEngine::DrawBackgroundImage()
         if (a >  Math::PI/4.0f)  a =  Math::PI/4.0f;
         if (a < -Math::PI/4.0f)  a = -Math::PI/4.0f;
 
-        u1 = -m_eyeDirH/Math::PI;
-        u2 = u1+1.0f/Math::PI;
+        // Note the background covers Math::PI radians, i.e. it repeats twice per rotation!
+        u1 = (-m_eyeDirH - GetHFovAngle()/2.0f) / Math::PI;
+        u2 = u1 + (GetHFovAngle() / Math::PI);
 
         v1 = (1.0f-h)*(0.5f+a/(2.0f*Math::PI/4.0f))+0.1f;
         v2 = v1+h;

src/graphics/engine/engine.h

@@ -921,12 +921,16 @@ class CEngine : public CSingleton<CEngine>
     void            SetTerrainVision(float vision);
 
     //@{
-    //! Management of camera angle
-    /**
+    //! Management of camera vertical field-of-view angle.
+    /** This is specified in radians.
+    Horizontal FoV is calculated based on vertical FoV and aspect ratio.
     0.75 = normal
     1.50 = wide-angle */
     void            SetFocus(float focus);
+    //! Deprecated alias for GetVFovAngle
     float           GetFocus();
+    float           GetVFovAngle();
+    float           GetHFovAngle();
     //@}
 
     //@{
@@ -1318,8 +1322,10 @@ class CEngine : public CSingleton<CEngine>
     Math::Matrix    m_matProj;
     //! View matrix for 3D scene
     Math::Matrix    m_matView;
-    //! Camera angle for 3D scene
+    //! Camera vertical field-of-view angle for 3D scene. A.k.a. m_vfov
     float           m_focus;
+    //! Horizontal field-of-view angle, calculated from vertical FOV and aspect ratio
+    float           m_hfov;
 
     //! Projection matrix for rendering shadow maps
     Math::Matrix    m_shadowProjMat;

src/graphics/engine/planet.cpp

@@ -115,8 +115,16 @@ void CPlanet::Draw()
 
         Math::Point p1, p2;
 
-        float a = eyeDirH + planet.angle.x;
-        p1.x = Math::Mod(a, Math::PI*2.0f)-0.5f;
+        // Determine the 2D coordinates of the centre of the planet.
+
+        // Not sure why this is + when you'd expect -. Perhaps one of the angles is inverted.
+        // Compute the camera-relative angles. (0, 0) is straight ahead (the dead centre of the screen).
+
+        // Why -1.0f? Simply because the old formula included that, and we need it to
+        // be consistent for the outer space cutscenes to work.
+        float a = planet.angle.x + eyeDirH - 1.0f;
+        a = Math::Mod(a+Math::PI, Math::PI*2.0f)-Math::PI; // normalize to -pi <= a < pi
+        p1.x = a/m_engine->GetHFovAngle() + 0.5f;
 
         a = eyeDirV + planet.angle.y;
         p1.y = 0.4f+(Math::Mod(a+Math::PI, Math::PI*2.0f)-Math::PI)*(2.0f/Math::PI);