Added world to screen conversion

- Added function WorldToScreen(...).
- Added world to screen example.
- Review GetMouseRay() comment.
- Removed deprecated lighting functions from raylib header.

3 files changed, 108 insertions, 22 deletions

diff --git a/examples/core_world_screen.c b/examples/core_world_screen.c
new file mode 100644
index 00000000..eac5fbdc
--- /dev/null
+++ b/examples/core_world_screen.c
@@ -0,0 +1,77 @@
+/*******************************************************************************************
+*
+*   raylib [core] example - World to screen
+*
+*   This example has been created using raylib 1.3 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2015 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+int main()
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    int screenWidth = 800;
+    int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [core] example - 3d camera free");
+
+    // Define the camera to look into our 3d world
+    Camera camera = {{ 0.0, 10.0, 10.0 }, { 0.0, 0.0, 0.0 }, { 0.0, 1.0, 0.0 }};
+
+    Vector3 cubePosition = { 0.0, 0.0, 0.0 };
+    
+    Vector2 cubeScreenPosition;
+    
+    SetCameraMode(CAMERA_FREE);         // Set a free camera mode
+    SetCameraPosition(camera.position); // Set internal camera position to match our camera position
+    SetCameraTarget(camera.target);     // Set internal camera target to match our camera target
+
+    SetTargetFPS(60);                   // Set our game to run at 60 frames-per-second
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())        // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        UpdateCamera(&camera);          // Update internal camera and our camera
+        
+        // Calculate cube screen space position (with a little offset to be in top)
+        cubeScreenPosition = WorldToScreen((Vector3){cubePosition.x, cubePosition.y + 2.5f, cubePosition.z}, camera);
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            Begin3dMode(camera);
+
+                DrawCube(cubePosition, 2, 2, 2, RED);
+                DrawCubeWires(cubePosition, 2, 2, 2, MAROON);
+
+                DrawGrid(10.0, 1.0);
+
+            End3dMode();
+            
+            DrawText("Enemy: 100 / 100", cubeScreenPosition.x - MeasureText("Enemy: 100 / 100", 20) / 2, cubeScreenPosition.y, 20, BLACK);
+            DrawText("Text is always on top of the cube", (screenWidth - MeasureText("Text is always on top of the cube", 20)) / 2, 25, 20, GRAY);
+            
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}
\ No newline at end of file
diff --git a/src/core.c b/src/core.c
index f1445cce..8b61aaf7 100644
--- a/src/core.c
+++ b/src/core.c
@@ -791,7 +791,7 @@ int StorageLoadValue(int position)
     return value;
 }
 
-// Gives the ray trace from mouse position
+// Returns a ray trace from mouse position
 //http://www.songho.ca/opengl/gl_transform.html
 //http://www.songho.ca/opengl/gl_matrix.html
 //http://www.sjbaker.org/steve/omniv/matrices_can_be_your_friends.html
@@ -857,6 +857,34 @@ Ray GetMouseRay(Vector2 mousePosition, Camera camera)
     return ray;
 }
 
+// Returns the screen space position from a 3d world space position
+Vector2 WorldToScreen(Vector3 position, Camera camera)
+{    
+    // Calculate projection matrix (from perspective instead of frustum
+    Matrix matProj = MatrixPerspective(45.0f, (float)((float)GetScreenWidth() / (float)GetScreenHeight()), 0.01f, 1000.0f);
+    
+    // Calculate view matrix from camera look at (and transpose it)
+    Matrix matView = MatrixLookAt(camera.position, camera.target, camera.up);
+    MatrixTranspose(&matView);
+    
+    // Convert world position vector to quaternion
+    Quaternion worldPos = { position.x, position.y, position.z, 1.0f };
+    
+    // Transform world position to view
+    QuaternionTransform(&worldPos, matView);
+    
+    // Transform result to projection (clip space position)
+    QuaternionTransform(&worldPos, matProj);
+    
+    // Calculate normalized device coordinates (inverted y)
+    Vector3 ndcPos = { worldPos.x / worldPos.w, -worldPos.y / worldPos.w, worldPos.z / worldPos.z };
+    
+    // Calculate 2d screen position vector
+    Vector2 screenPosition = { (ndcPos.x + 1.0f) / 2.0f * GetScreenWidth(), (ndcPos.y + 1.0f) / 2.0f * GetScreenHeight() };
+    
+    return screenPosition;
+}
+
 //----------------------------------------------------------------------------------
 // Module Functions Definition - Input (Keyboard, Mouse, Gamepad) Functions
 //----------------------------------------------------------------------------------
diff --git a/src/raylib.h b/src/raylib.h
index 4d8d104d..d6b28e53 100644
--- a/src/raylib.h
+++ b/src/raylib.h
@@ -527,7 +527,8 @@ void EndDrawing(void);                                      // End canvas drawin
 void Begin3dMode(Camera cam);                               // Initializes 3D mode for drawing (Camera setup)
 void End3dMode(void);                                       // Ends 3D mode and returns to default 2D orthographic mode
 
-Ray GetMouseRay(Vector2 mousePosition, Camera camera);      // TODO: Returns a ray trace from mouse position
+Ray GetMouseRay(Vector2 mousePosition, Camera camera);      // Returns a ray trace from mouse position
+Vector2 WorldToScreen(Vector3 position, Camera camera);     // Returns the screen space position from a 3d world space position
 
 void SetTargetFPS(int fps);                                 // Set target FPS (maximum)
 float GetFPS(void);                                         // Returns current FPS
@@ -787,26 +788,6 @@ void SetShaderMap(Shader *shader, int mapLocation, Texture2D texture, int textur
 void SetBlendMode(int mode);                                        // Set blending mode (alpha, additive, multiplied)
 
 //----------------------------------------------------------------------------------
-// Lighting System Functions (engine-module: lighting)
-// NOTE: light and material structs uses float pointers instead of vectors to be compatible with SetShaderValue()
-//----------------------------------------------------------------------------------
-// Lights functions
-void SetLightPosition(Light *light, Vector3 position);                  // Set light position converting position vector to float pointer
-void SetLightRotation(Light *light, Vector3 rotation);                  // Set light rotation converting rotation vector to float pointer
-void SetLightIntensity(Light *light, float intensity);                  // Set light intensity value 
-void SetLightAmbientColor(Light *light, Vector3 color);                 // Set light ambient color value (it will be multiplied by material ambient color)
-void SetLightDiffuseColor(Light *light, Vector3 color);                 // Set light diffuse color (light color)
-void SetLightSpecularColor(Light *light, Vector3 color);                // Set light specular color (it will be multiplied by material specular color)
-void SetLightSpecIntensity(Light *light, float specIntensity);          // Set light specular intensity (specular color scalar multiplier)
-
-// Materials functions
-void SetMaterialAmbientColor(Material *material, Vector3 color);        // Set material ambient color value (it will be multiplied by light ambient color)
-void SetMaterialDiffuseColor(Material *material, Vector3 color);        // Set material diffuse color (material color, should use DrawModel() tint parameter)
-void SetMaterialSpecularColor(Material *material, Vector3 color);       // Set material specular color (it will be multiplied by light specular color)
-void SetMaterialGlossiness(Material *material, float glossiness);       // Set material glossiness value (recommended values: 0 - 100)
-void SetMaterialNormalDepth(Material *material, float depth);           // Set normal map depth (B component from RGB type map scalar multiplier)
-
-//----------------------------------------------------------------------------------
 // Physics System Functions (engine-module: physics)
 //----------------------------------------------------------------------------------
 void InitPhysics(void);                                                     // Initialize all internal physics values