Added skybox example

examples/models/models_skybox.c

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+/*******************************************************************************************
+*
+*   raylib [models] example - Skybox loading and drawing
+*
+*   This example has been created using raylib 1.8 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2017 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+#include "raymath.h"
+
+int main()
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    int screenWidth = 800;
+    int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [models] example - skybox loading and drawing");
+
+    // Define the camera to look into our 3d world
+    Camera camera = {{ 1.0f, 1.0f, 1.0f }, { 0.0f, 0.0f, 0.0f }, { 0.0f, 1.0f, 0.0f }, 45.0f };
+
+    // Load skybox model and shader
+    #define PATH_SKYBOX_VS      "resources/shaders/skybox.vs"       // Path to skybox vertex shader
+    #define PATH_SKYBOX_FS      "resources/shaders/skybox.fs"       // Path to skybox vertex shader
+    #define PATH_TEXTURES_HDR   "resources/pinetree.hdr"
+    #define LOC_CUSTOM_SKYRESOLUTION    15
+    
+    Mesh cube = GenMeshCube(1.0f, 1.0f, 1.0f);
+    Model skybox = LoadModelFromMesh(cube, false);
+    skybox.material.shader = LoadShader(PATH_SKYBOX_VS, PATH_SKYBOX_FS);
+
+    Texture2D texHDR = LoadTexture(PATH_TEXTURES_HDR);
+    skybox.material.maps[TEXMAP_CUBEMAP].tex = rlGenMapCubemap(texHDR, 512);
+    SetShaderValuei(skybox.material.shader, GetShaderLocation(skybox.material.shader, "environmentMap"), (int[1]){ TEXMAP_CUBEMAP }, 1);
+
+    // Get skybox shader locations
+    int skyProjectionLoc = GetShaderLocation(skybox.material.shader, "projection");
+    skybox.material.shader.locs[LOC_MATRIX_VIEW] = GetShaderLocation(skybox.material.shader, "view");
+    
+    // Then before rendering, configure the viewport to the actual screen dimensions
+    Matrix proj = MatrixPerspective(45.0, (double)GetScreenWidth()/(double)GetScreenHeight(), 0.01, 1000.0);
+    MatrixTranspose(&proj);
+    SetShaderValueMatrix(skybox.material.shader, skyProjectionLoc, proj);
+
+    SetCameraMode(camera, CAMERA_ORBITAL);  // Set an orbital camera mode
+
+    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 camera
+        
+        Matrix view = MatrixLookAt(camera.position, camera.target, camera.up);
+        SetShaderValueMatrix(skybox.material.shader, skybox.material.shader.locs[LOC_MATRIX_VIEW], view);
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            Begin3dMode(camera);
+
+                DrawModel(skybox, VectorZero(), 1.0f, RED);
+                
+                DrawGrid(10, 1.0f);
+
+            End3dMode();
+
+            DrawFPS(10, 10);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    UnloadModel(skybox);        // Unload skybox model
+
+    CloseWindow();              // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}

examples/models/resources/shaders/cubemap.fs

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+/*******************************************************************************************
+*
+*   rPBR [shader] - Equirectangular to cubemap fragment shader
+*
+*   Copyright (c) 2017 Victor Fisac
+*
+**********************************************************************************************/
+
+#version 330
+
+// Input vertex attributes (from vertex shader)
+in vec3 fragPos;
+
+// Input uniform values
+uniform sampler2D equirectangularMap;
+
+// Output fragment color
+out vec4 finalColor;
+
+vec2 SampleSphericalMap(vec3 v)
+{
+    vec2 uv = vec2(atan(v.z, v.x), asin(v.y));
+    uv *= vec2(0.1591, 0.3183);
+    uv += 0.5;
+    return uv;
+}
+
+void main()
+{
+    // Normalize local position 
+    vec2 uv = SampleSphericalMap(normalize(fragPos));
+
+    // Fetch color from texture map
+    vec3 color = texture(equirectangularMap, uv).rgb;
+
+    // Calculate final fragment color
+    finalColor = vec4(color, 1.0);
+}

examples/models/resources/shaders/cubemap.vs

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+/*******************************************************************************************
+*
+*   rPBR [shader] - Equirectangular to cubemap vertex shader
+*
+*   Copyright (c) 2017 Victor Fisac
+*
+**********************************************************************************************/
+
+#version 330
+
+// Input vertex attributes
+in vec3 vertexPosition;
+
+// Input uniform values
+uniform mat4 projection;
+uniform mat4 view;
+
+// Output vertex attributes (to fragment shader)
+out vec3 fragPos;
+
+void main()
+{
+    // Calculate fragment position based on model transformations
+    fragPos = vertexPosition;
+
+    // Calculate final vertex position
+    gl_Position = projection*view*vec4(vertexPosition, 1.0);
+}

examples/models/resources/shaders/skybox.fs

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+/*******************************************************************************************
+*
+*   rPBR [shader] - Background skybox fragment shader
+*
+*   Copyright (c) 2017 Victor Fisac
+*
+**********************************************************************************************/
+
+#version 330
+
+// Input vertex attributes (from vertex shader)
+in vec3 fragPos;
+
+// Input uniform values
+uniform samplerCube environmentMap;
+
+// Output fragment color
+out vec4 finalColor;
+
+void main()
+{
+    // Fetch color from texture map
+    vec3 color = texture(environmentMap, fragPos).rgb;
+
+    // Apply gamma correction
+    color = color/(color + vec3(1.0));
+    color = pow(color, vec3(1.0/2.2));
+
+    // Calculate final fragment color
+    finalColor = vec4(color, 1.0);
+}

examples/models/resources/shaders/skybox.vs

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+/*******************************************************************************************
+*
+*   rPBR [shader] - Background skybox vertex shader
+*
+*   Copyright (c) 2017 Victor Fisac
+*
+**********************************************************************************************/
+
+#version 330
+
+// Input vertex attributes
+in vec3 vertexPosition;
+
+// Input uniform values
+uniform mat4 projection;
+uniform mat4 view;
+
+// Output vertex attributes (to fragment shader)
+out vec3 fragPos;
+
+void main()
+{
+    // Calculate fragment position based on model transformations
+    fragPos = vertexPosition;
+
+    // Remove translation from the view matrix
+    mat4 rotView = mat4(mat3(view));
+    vec4 clipPos = projection*rotView*vec4(vertexPosition, 1.0);
+
+    // Calculate final vertex position
+    gl_Position = clipPos.xyww;
+}