Allow changing the fov and render distance

include/JGL/JGL.h

@@ -200,6 +200,9 @@ namespace JGL {
 
     /// Drawing functions for primitive 3D Shapes.
     namespace J3D {
+        void Init(const Vector2& window_size, float fov, float far_plane);
+        void ChangeFOV(float fov);
+        void ChangeFarPlane(float far_plane);
         void Begin();
         void End();
         void SetMatrix(const std::vector<GLfloat>& matrix, const Vector2& window_size);

main.cpp

@@ -71,17 +71,6 @@ private:
 
 
 Texture* image;
-//The Re3D style base projection.
-std::vector<GLfloat> perspective(float fov, float aspect, float nearPlane, float farPlane) {
-    std::vector<float> result(16);
-    float f = 1.0f / tan(fov * 0.5f * M_PI / 180.0f);
-    result[0] = f / aspect;
-    result[5] = f;
-    result[10] = (farPlane + nearPlane) / (nearPlane - farPlane);
-    result[11] = -1.0f;
-    result[14] = (2.0f * farPlane * nearPlane) / (nearPlane - farPlane);
-    return result;
-}
 
 class Camera {
 public:
@@ -133,22 +122,15 @@ class JGLDemoWindow : public ReWindow::RWindow
 public:
     void initGL() {
         camera = new Camera;
-        auto window_size = getSize();
-        auto aspect = (float) window_size[0] / (float) window_size[1];
 
         gladLoadGL();
         JGL::InitTextEngine();
         JGL::Update(getSize());
+        J3D::Init(getSize(), 90, 100);
         FreeSans = JGL::Font("assets/fonts/FreeSans.ttf");
         Jupiteroid = JGL::Font("assets/fonts/Jupiteroid.ttf");
 
-        glMatrixMode(GL_PROJECTION);
-        glLoadIdentity();
-        glMultMatrixf(perspective(75, aspect, 0.001, 100).data());
-        glMatrixMode(GL_MODELVIEW);
-        glLoadIdentity();
         glClearColor(0.f, 0.f, 0.f, 0.f);
-        glViewport(0,0,window_size.x,window_size.y);
         glEnable(GL_DEPTH_TEST);
         glDepthFunc(GL_LESS);
         glDepthMask(GL_TRUE);
@@ -156,8 +138,22 @@ public:
     }
 
     Vector3 textAngle = {0,0,0};
+    float fov = 90;
+    bool fov_increasing = true;
+
     void display() {
         JGL::Update(getSize());
+        if (fov_increasing)
+            fov += 0.25;
+        else
+            fov -= 0.50;
+
+        if (fov >= 120)
+            fov_increasing = false;
+        else if (fov <= 75)
+            fov_increasing = true;
+        J3D::ChangeFOV(fov);
+
         textAngle.y += 2.0f;
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
         glMatrixMode(GL_MODELVIEW);

src/JGL.cpp

@@ -529,7 +529,46 @@ namespace JGL {
 
     }
 
+    //The 3D projection.
+    std::vector<GLfloat> perspective(float fov, float aspect, float nearPlane, float farPlane) {
+        std::vector<float> result(16);
+        float f = 1.0f / tan(fov * 0.5f * M_PI / 180.0f);
+        result[0] = f / aspect;
+        result[5] = f;
+        result[10] = (farPlane + nearPlane) / (nearPlane - farPlane);
+        result[11] = -1.0f;
+        result[14] = (2.0f * farPlane * nearPlane) / (nearPlane - farPlane);
+        return result;
+    }
+
+    bool j3d_initialized = false;
+    float j3d_far_plane = 0;
+    float j3d_fov = 0;
+
+    void J3D::Init(const J3ML::LinearAlgebra::Vector2& window_size, float fov, float far_plane) {
+        wS = window_size;
+        j3d_far_plane = far_plane;
+        j3d_fov = fov;
+        j3d_initialized = true;
+    }
+
+    void J3D::ChangeFOV(float fov) {
+        j3d_fov = fov;
+    }
+
+    void J3D::ChangeFarPlane(float far_plane) {
+        j3d_far_plane = far_plane;
+    }
+
     void J3D::Begin() {
+        if (!j3d_initialized)
+            throw std::runtime_error("You have to run J3D::Init before rendering 3D elements.");
+
+        auto aspect = (float) wS.x / (float) wS.y;
+        glMatrixMode(GL_PROJECTION);
+        glLoadIdentity();
+        glMultMatrixf(perspective(j3d_fov, aspect, 0.001, j3d_far_plane).data());
+        glMatrixMode(GL_MODELVIEW);
 
         //Get what the draw color was before we did anything.
         glGetFloatv(GL_CURRENT_COLOR, oldColor);