world to screen transformation

src/controlpanel.c

 #include "controlpanel.h"
+
+#include "raylib.h"
+
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -18,13 +21,64 @@ void Panel_delete(Panel * self)
 void Panel_initialize(Panel * self, NetWorld * world)
 {
     self->world= world;
-    self->camerax= 0;
-    self->cameray= 0;
-    self->scale= 1;
+    self->camera.x= 0.f;
+    self->camera.y= 0.f;
+    self->screenCenter.x= 400.f;
+    self->screenCenter.y= 300.f;
+    self->scale= 10.f; //pixel per meters
 }
 
 // To String
 void Panel_print(Panel * self)
 {
-    printf("Panel camera(x-%f, y-%f, scale-%f)\n", self->camerax, self->cameray, self->scale);
+    printf( "Panel camera(x-%f, y-%f, scale-%f)\n",
+            self->camera.x,
+            self->camera.y,
+            self->scale);
+}
+
+// Rendering
+void Panel_draw(Panel * self)
+{
+    BeginDrawing();
+    ClearBackground(RAYWHITE);
+    for(int i= 0 ; i < self->world->size ; ++i )
+    {
+        Panel_drawNode( self, &(self->world->nodes[i]) );
+    }
+    Panel_drawBasis(self);
+    EndDrawing(); 
+}
+
+void Panel_drawBasis(Panel * self)
+{
+    Vector2 screen10= {1.f, 0.f};
+    screen10= Panel_pixelFromPosition(self, &( screen10 ) );
+    Vector2 screen01= {0.f, 1.f}; 
+    screen01= Panel_pixelFromPosition(self, &( screen01 ) );
+    DrawCircleV( self->screenCenter, 4, BLUE );   
+    DrawLineV( self->screenCenter, screen10, RED );
+    DrawLineV( self->screenCenter, screen01, BLUE );
+}
+
+void Panel_drawNode(Panel * self, Node * n)
+{
+    Vector2 screenPosition= Panel_pixelFromPosition(self, &(n->position) );
+    DrawCircleV(screenPosition, 24, MAROON);
+    DrawCircleV(screenPosition, 20, RAYWHITE);
+}
+
+Vector2 Panel_pixelFromPosition(Panel * self, Vector2 * p)
+{
+    Vector2 pixel= {
+        self->screenCenter.x + (p->x - self->camera.x ) * self->scale,
+        self->screenCenter.y - (p->y - self->camera.y ) * self->scale
+    };
+    return pixel;
+}
+
+Vector2 Panel_positionFromPixel(Panel * self, Vector2 * p)
+{
+    Vector2 position= { p->x, p->y };
+    return position;
 }

src/controlpanel.h

@@ -4,8 +4,8 @@
 #include "networld.h"
 
 struct Str_Panel {
-    double camerax, cameray;
-    double scale;
+    Vector2 camera, screenCenter;
+    float scale; // meter per pixel
     NetWorld * world;
 };
 
@@ -21,4 +21,11 @@ void Panel_initialize(Panel * self, NetWorld * world);
 // To String
 void Panel_print(Panel * self);
 
+// Rendering
+void Panel_draw(Panel * self);
+void Panel_drawBasis(Panel * self);
+void Panel_drawNode(Panel * self, Node * n);
+Vector2 Panel_pixelFromPosition(Panel * self, Vector2 * p);
+Vector2 Panel_positionFromPixel(Panel * self, Vector2 * p);
+
 #endif //CONTROLPANEL_H
\ No newline at end of file

src/main-viewer.c

@@ -16,11 +16,10 @@
 // Program attributes
 //-------------------
 const int screenWidth = 800;
-const int screenHeight = 450;
+const int screenHeight = 600;
 const int targetFPS = 60;
 
 void game_update(NetWorld * world);
-void game_draw(NetWorld * world);
 
 // Game attributes
 //-----------------
@@ -32,9 +31,9 @@ int main(int nbArg, char ** arg)
     //--------------------
     game_end= false;
     NetWorld * world= NetWorld_new(3);
-    NetWorld_initNodePosition( world, 0, 10.4, 12.8 );
-    NetWorld_initNodePosition( world, 1, 110.4, 52.8 );
-    NetWorld_initNodePosition( world, 2, 384.5, 422.2 );
+    NetWorld_initNodePosition( world, 0, 1.4f, 1.28f );
+    NetWorld_initNodePosition( world, 1, 11.0f, 32.8f );
+    NetWorld_initNodePosition( world, 2, 18.4f, -12.2f );
 
     Panel * panel= Panel_new();
     Panel_initialize(panel, world);
@@ -50,12 +49,15 @@ int main(int nbArg, char ** arg)
     NetWorld_print(world);
     puts("world expected:\n[10.4, 12.8]\n[110.4, 52.8]\n[384.5, 422.2]");
     Panel_print(panel);
-    
+    Vector2 position= {1.f, 1.f};
+    position= Panel_pixelFromPosition( panel, &position );
+    printf("[%.2f,%.2f]\n", position.x, position.y);
+
     // Main game loop
     while (!game_end && !WindowShouldClose())    // Detect window close button or ESC key
     {
         game_update(world);
-        game_draw(world);
+        Panel_draw(panel);
     }
 
     // proper closing
@@ -70,15 +72,3 @@ void game_update(NetWorld * world)
 {
 
 }
-
-void game_draw(NetWorld * world)
-{
-    BeginDrawing();
-    ClearBackground(RAYWHITE);
-    for(int i= 0 ; i < world->size ; ++i )
-    {
-        Vector2 nodePosition= { world->nodes[i].x, world->nodes[i].y };
-        DrawCircleV(nodePosition, 24, MAROON);
-    }
-    EndDrawing();
-}

src/networld.c

@@ -20,15 +20,15 @@ void NetWorld_delete(NetWorld * self)
 // Initialization
 void NetWorld_initNodePosition(
     NetWorld * self, int iNode,
-    double x, double y)
+    float x, float y)
 {
-    self->nodes[iNode].x= x;
-    self->nodes[iNode].y= y;
+    self->nodes[iNode].position.x= x;
+    self->nodes[iNode].position.y= y;
 }
 
 // To String
 void NetWorld_print(NetWorld * self)
 {
     for(int i= 0 ; i < self->size ; ++i )
-        printf("[%lf, %lf]\n", self->nodes[i].x, self->nodes[i].y);
+        printf("[%.2f, %.2f]\n", self->nodes[i].position.x, self->nodes[i].position.y);
 }

src/networld.h

 #ifndef NETWORLD_H
 #define NETWORLD_H
 
+#include "raylib.h"
+
 struct Str_Node {
-    double x, y;
+    Vector2 position;
 };
 typedef struct Str_Node Node;
 
@@ -17,7 +19,7 @@ NetWorld * NetWorld_new(int aSize);
 void NetWorld_delete(NetWorld * self);
 
 // Initialization
-void NetWorld_initNodePosition(NetWorld * self, int iNode, double x, double y); // position must be an float[size][2] array...
+void NetWorld_initNodePosition(NetWorld * self, int iNode, float x, float y); // position must be an float[size][2] array...
 
 // To String
 void NetWorld_print(NetWorld * self);