[examples] Add new example: shaders_vertex_displacement (#4186)

* shaders-vertex_displacement init

* implement simulation of wave in ocean

* update examples/README & add some comments

* update comments

* add gl100 shaders

examples/shaders/shaders_vertex_displacement.c

@@ -0,0 +1,122 @@
+/*******************************************************************************************
+*
+*   raylib [shaders] example - Vertex displacement
+*
+*   Example originally created with raylib 5.0, last time updated with raylib 4.5
+*
+*   Example contributed by <Alex ZH> (@ZzzhHe) and reviewed by Ramon Santamaria (@raysan5)
+*
+*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+*   BSD-like license that allows static linking with closed source software
+*
+*   Copyright (c) 2023 <Alex ZH> (@ZzzhHe)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+#include "raymath.h"
+#include "rlgl.h"
+
+#include <printf.h>
+
+#define RLIGHTS_IMPLEMENTATION
+#include "rlights.h"
+
+#if defined(PLATFORM_DESKTOP)
+    #define GLSL_VERSION            330
+#else   // PLATFORM_ANDROID, PLATFORM_WEB
+    #define GLSL_VERSION            100
+#endif
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [shaders] example - vertex displacement");
+
+    // set up camera
+    Camera camera = {0};
+    camera.position = (Vector3) {20.0f, 5.0f, -20.0f};
+    camera.target = (Vector3) {0.0f, 0.0f, 0.0f};
+    camera.up = (Vector3) {0.0f, 1.0f, 0.0f};
+    camera.fovy = 60.0f;
+    camera.projection = CAMERA_PERSPECTIVE;
+
+    // Load vertex and fragment shaders
+    Shader shader = LoadShader(
+        TextFormat("resources/shaders/glsl%i/vertex_displacement.vs", GLSL_VERSION),
+        TextFormat("resources/shaders/glsl%i/vertex_displacement.fs", GLSL_VERSION)
+        );
+    
+    // Load perlin noise texture
+    Image perlinNoiseImage = GenImagePerlinNoise(512, 512, 0, 0, 1.0f);
+    Texture perlinNoiseMap = LoadTextureFromImage(perlinNoiseImage);
+    UnloadImage(perlinNoiseImage);
+
+    // Set shader uniform location
+    int perlinNoiseMapLoc = GetShaderLocation(shader, "perlinNoiseMap");
+    rlEnableShader(shader.id);
+    rlActiveTextureSlot(1);
+    rlEnableTexture(perlinNoiseMap.id);
+    rlSetUniformSampler(perlinNoiseMapLoc, 1);
+    
+    // Create a plane mesh and model
+    Mesh planeMesh = GenMeshPlane(50, 50, 50, 50);
+    Model planeModel = LoadModelFromMesh(planeMesh);
+    // Set plane model material
+    planeModel.materials[0].shader = shader;
+
+    float time = 0.0f;
+
+    SetTargetFPS(60);
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        UpdateCamera(&camera, CAMERA_FREE); // Update camera
+
+        time += GetFrameTime(); // Update time variable
+        SetShaderValue(shader, GetShaderLocation(shader, "time"), &time, SHADER_UNIFORM_FLOAT); // Send time value to shader
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            BeginMode3D(camera);
+
+                BeginShaderMode(shader);
+                    // Draw plane model
+                    DrawModel(planeModel, (Vector3){ 0.0f, 0.0f, 0.0f }, 1.0f, (Color) {255, 255, 255, 255});
+                EndShaderMode();
+
+            EndMode3D();
+
+            DrawText("Vertex displacement", 10, 10, 20, DARKGRAY);
+            DrawFPS(10, 40);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+
+    UnloadShader(shader);
+    UnloadModel(planeModel);
+
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}