Add standard lighting (2/3)

- 3 light types added (point, directional, spot).
- DrawLights() function added using line shapes.
- Standard lighting example added.
- Removed useless struct variables from material and light.
- Fixed light attributes dynamic locations errors.
- Standard vertex and fragment shaders temporally added until rewrite it
as char pointers in rlgl.
TODO:
- Add normal and specular maps calculations in standard shader.
- Add control structs to handle which attributes needs to be calculated
(textures, specular...).
- Adapt standard shader to version 110.
- Rewrite standard shader as char pointers in rlgl.

examples/resources/shaders/standard.fs

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+#version 330
+
+in vec3 fragPosition;
+in vec2 fragTexCoord;
+in vec4 fragColor;
+in vec3 fragNormal;
+
+out vec4 finalColor;
+
+uniform sampler2D texture0;
+
+uniform vec4 colAmbient;
+uniform vec4 colDiffuse;
+uniform vec4 colSpecular;
+uniform float glossiness;
+
+uniform mat4 modelMatrix;
+uniform vec3 viewDir;
+
+struct Light {
+    int enabled;
+    int type;
+    vec3 position;
+    vec3 direction;
+    vec4 diffuse;
+    float intensity;
+    float attenuation;
+    float coneAngle;
+};
+
+const int maxLights = 8;
+uniform int lightsCount;
+uniform Light lights[maxLights];
+
+vec3 CalcPointLight(Light l, vec3 n, vec3 v)
+{
+    vec3 surfacePos = vec3(modelMatrix*vec4(fragPosition, 1));
+    vec3 surfaceToLight = l.position - surfacePos;
+    
+    // Diffuse shading
+    float brightness = clamp(dot(n, surfaceToLight)/(length(surfaceToLight)*length(n)), 0, 1);
+    float diff = 1.0/dot(surfaceToLight/l.attenuation, surfaceToLight/l.attenuation)*brightness*l.intensity;
+    
+    // Specular shading
+    float spec = 0.0;
+    if(diff > 0.0)
+    {
+        vec3 h = normalize(-l.direction + v);
+        spec = pow(dot(n, h), 3 + glossiness);
+    }
+    
+    return (diff*l.diffuse.rgb*colDiffuse.rgb + spec*colSpecular.rgb);
+}
+
+vec3 CalcDirectionalLight(Light l, vec3 n, vec3 v)
+{
+    vec3 lightDir = normalize(-l.direction);
+    
+    // Diffuse shading
+    float diff = clamp(dot(n, lightDir), 0.0, 1.0)*l.intensity;
+    
+    // Specular shading
+    float spec = 0.0;
+    if(diff > 0.0)
+    {
+        vec3 h = normalize(lightDir + v);
+        spec = pow(dot(n, h), 3 + glossiness);
+    }
+    
+    // Combine results
+    return (diff*l.intensity*l.diffuse.rgb*colDiffuse.rgb + spec*colSpecular.rgb);
+}
+
+vec3 CalcSpotLight(Light l, vec3 n, vec3 v)
+{
+    vec3 surfacePos = vec3(modelMatrix*vec4(fragPosition, 1));
+    vec3 lightToSurface = normalize(surfacePos - l.position);
+    vec3 lightDir = normalize(-l.direction);
+    
+    // Diffuse shading
+    float diff = clamp(dot(n, lightDir), 0.0, 1.0)*l.intensity;
+    
+    // Spot attenuation
+    float attenuation = clamp(dot(n, lightToSurface), 0.0, 1.0);
+    attenuation = dot(lightToSurface, -lightDir);
+    float lightToSurfaceAngle = degrees(acos(attenuation));
+    if(lightToSurfaceAngle > l.coneAngle) attenuation = 0.0;
+    float falloff = (l.coneAngle - lightToSurfaceAngle)/l.coneAngle;
+    
+    // Combine diffuse and attenuation
+    float diffAttenuation = diff*attenuation;
+    
+    // Specular shading
+    float spec = 0.0;
+    if(diffAttenuation > 0.0)
+    {
+        vec3 h = normalize(lightDir + v);
+        spec = pow(dot(n, h), 3 + glossiness);
+    }
+    
+    return falloff*(diffAttenuation*l.diffuse.rgb + spec*colSpecular.rgb);
+}
+
+void main()
+{
+    // Calculate fragment normal in screen space
+    mat3 normalMatrix = transpose(inverse(mat3(modelMatrix)));
+    vec3 normal = normalize(normalMatrix*fragNormal);
+   
+    // Normalize normal and view direction vectors
+    vec3 n = normalize(normal);
+    vec3 v = normalize(viewDir);
+
+    // Calculate diffuse texture color fetching
+    vec4 texelColor = texture(texture0, fragTexCoord);
+    vec3 lighting = colAmbient.rgb;
+    
+    for(int i = 0; i < lightsCount; i++)
+    {
+        // Check if light is enabled
+        if(lights[i].enabled == 1)
+        {
+            // Calculate lighting based on light type
+            switch(lights[i].type)
+            {
+                case 0: lighting += CalcPointLight(lights[i], n, v); break;
+                case 1: lighting += CalcDirectionalLight(lights[i], n, v); break;
+                case 2: lighting += CalcSpotLight(lights[i], n, v); break;
+                default: break;
+            }
+        }
+    }
+    
+    // Calculate final fragment color
+    finalColor = vec4(texelColor.rgb*lighting, texelColor.a);
+}

examples/resources/shaders/standard.vs

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+#version 330 
+
+in vec3 vertexPosition;
+in vec3 vertexNormal;
+in vec2 vertexTexCoord;
+in vec4 vertexColor;
+
+out vec3 fragPosition;
+out vec2 fragTexCoord;
+out vec4 fragColor;
+out vec3 fragNormal;
+
+uniform mat4 mvpMatrix;
+
+void main()
+{
+    fragPosition = vertexPosition;
+    fragTexCoord = vertexTexCoord;
+    fragColor = vertexColor;
+    fragNormal = vertexNormal;
+
+    gl_Position = mvpMatrix*vec4(vertexPosition, 1.0);
+}

examples/shaders_standard_lighting.c

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+/*******************************************************************************************
+*
+*   raylib [shaders] example - Standard lighting (materials and lights)
+*
+*   NOTE: This example requires raylib OpenGL 3.3 or ES2 versions for shaders support,
+*         OpenGL 1.1 does not support shaders, recompile raylib to OpenGL 3.3 version.
+*
+*   NOTE: Shaders used in this example are #version 330 (OpenGL 3.3), to test this example
+*         on OpenGL ES 2.0 platforms (Android, Raspberry Pi, HTML5), use #version 100 shaders
+*         raylib comes with shaders ready for both versions, check raylib/shaders install folder
+*
+*   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) 2016 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+#include "raymath.h"
+
+int main()
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    int screenWidth = 800;
+    int screenHeight = 450;
+    
+    SetConfigFlags(FLAG_MSAA_4X_HINT);      // Enable Multi Sampling Anti Aliasing 4x (if available)
+
+    InitWindow(screenWidth, screenHeight, "raylib [shaders] example - model shader");
+
+    // Define the camera to look into our 3d world
+    Camera camera = {{ 4.0f, 4.0f, 4.0f }, { 0.0f, 1.5f, 0.0f }, { 0.0f, 1.0f, 0.0f }, 45.0f };
+    Vector3 position = { 0.0f, 0.0f, 0.0f };   // Set model position
+    
+    Model dwarf = LoadModel("resources/model/dwarf.obj");                   // Load OBJ model
+    Texture2D texDiffuse = LoadTexture("resources/model/dwarf_diffuse.png");   // Load model diffuse texture
+
+    Material material = LoadStandardMaterial();
+    material.texDiffuse = texDiffuse;
+    material.colDiffuse = (Color){255, 255, 255, 255};
+    material.colAmbient = (Color){0, 0, 10, 255};
+    material.colSpecular = (Color){255, 255, 255, 255};
+    material.glossiness = 50.0f;
+    dwarf.material = material;      // Apply material to model
+    
+    Light spotLight = CreateLight(LIGHT_SPOT, (Vector3){3.0f, 5.0f, 2.0f}, (Color){255, 255, 255, 255});
+    spotLight->target = (Vector3){0.0f, 0.0f, 0.0f};
+    spotLight->intensity = 2.0f;
+    spotLight->diffuse = (Color){255, 100, 100, 255};
+    spotLight->coneAngle = 60.0f;
+    
+    Light dirLight = CreateLight(LIGHT_DIRECTIONAL, (Vector3){0.0f, -3.0f, -3.0f}, (Color){255, 255, 255, 255});
+    dirLight->target = (Vector3){1.0f, -2.0f, -2.0f};
+    dirLight->intensity = 2.0f;
+    dirLight->diffuse = (Color){100, 255, 100, 255};
+    
+    Light pointLight = CreateLight(LIGHT_POINT, (Vector3){0.0f, 4.0f, 5.0f}, (Color){255, 255, 255, 255});
+    pointLight->intensity = 2.0f;
+    pointLight->diffuse = (Color){100, 100, 255, 255};
+    pointLight->attenuation = 3.0f;
+
+    // Setup orbital camera
+    SetCameraMode(CAMERA_ORBITAL);          // Set a orbital 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
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            Begin3dMode(camera);
+
+                DrawModel(dwarf, position, 2.0f, WHITE);   // Draw 3d model with texture
+                
+                DrawLights();   // Draw all created lights in 3D world
+
+                DrawGrid(10, 1.0f);     // Draw a grid
+
+            End3dMode();
+            
+            DrawText("(c) Dwarf 3D model by David Moreno", screenWidth - 200, screenHeight - 20, 10, GRAY);
+
+            DrawFPS(10, 10);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadMaterial(material);   // Unload material and assigned textures
+    UnloadModel(dwarf);         // Unload model
+    
+    // Destroy all created lights
+    DestroyLight(pointLight);
+    DestroyLight(dirLight);
+    DestroyLight(spotLight);
+
+    CloseWindow();              // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}