height function for terrain

Author: Cheng Xie

src/camera.cpp

@@ -10,7 +10,7 @@ Camera::Camera()
     heightAngle_ = 60;
 
     updateProjection();
-    lookAt({3, 3, 3}, {0, 0, 0}, {0, 1, 0});
+    lookAt({-100, 20, 100}, {0, 0, 0}, {0, 1, 0});
 }
 
 void Camera::apply(DrawContext &context)

src/meshutility.cpp

@@ -98,8 +98,6 @@ Mesh *MeshUtility::createPlane(int tessellationLevel, float size)
 
     vec3 dy = (upperleft - lowerleft) / tessellationLevel;
 
-    cout << dy << endl;
-    
     float width = (lowerright - lowerleft).length();
     float height = (upperleft - lowerleft).length();
 

src/scene.cpp

@@ -41,16 +41,13 @@ void Scene::initialize()
     material1->setShiness(100);
 
     // Textures are owned by cache
-    Texture* diffuseMap = TextureCache::getInstance()->acquire("frostmourne", TextureType::Texture2D);
+    Texture* diffuseMap = TextureCache::getInstance()->acquire("cheese", TextureType::Texture2D);
     material1->setDiffuseMap(diffuseMap);
 
     SceneObject* obj1 = new SceneObject;
-    Mesh* mesh1 = MeshCache::getInstance()->acquire("frostmourne");
+    Mesh* mesh1 = MeshCache::getInstance()->acquire("cube");
     obj1->setMesh(mesh1);
     obj1->setMaterial(material1);
-    
-    obj1->transform().translate(0, 50, 0);
-    obj1->transform().scale(20, 20, 20);
 
     sceneObjects_.push_back(obj1);
 
@@ -66,11 +63,17 @@ void Scene::initialize()
 
     Terrain* terrain = new Terrain({0, 0, 0}, size);
     sceneObjects_.push_back(terrain);
+    
+    float x = -100;
+    float z = 100;
+    float y = terrain->height(x, z);
+    
+    obj1->transform().translate(x, y, z);
 
     // Get a tornado in here!
     vec3 tornadoStart;
     tornadoStart.setX(0.0);
-    tornadoStart.setY(50);
+    tornadoStart.setY(0);
     tornadoStart.setZ(0.0);
     tornado_ = new Tornado(tornadoStart);
     tornadoStart.setX(8.0);
@@ -88,7 +91,7 @@ void Scene::render(DrawContext &context)
     context.sceneObjects = &sceneObjects_;
     context.scene = this;
 
-    //skybox_->render(context);
+    skybox_->render(context);
 
     for (SceneObject* object : sceneObjects_) {
         object->render(context);

src/sceneobject.h

@@ -15,7 +15,6 @@ class SceneObject
 
     const Material *material() const;
     void setMaterial(Material *material);
-    Material* getMaterial(){return material_;}
 
     mat4& transform();
     const mat4& transform() const;

src/terrain.cpp

@@ -3,10 +3,16 @@
 #include "terrainmaterial.h"
 #include "mesh.h"
 #include "texturecache.h"
+#include "texture.h"
 
-Terrain::Terrain(const vec3& center, int size)
+Terrain::Terrain(const vec3& center, float size)
 {
-    mesh_ = MeshUtility::createPlane(200, size / 2);
+    size_ = size;
+    center_ = center;
+    
+    heightScale_ = 20;
+    
+    mesh_ = MeshUtility::createPlane(200, size);
 
     TerrainMaterial* material = new TerrainMaterial;
     material->setAmbient({0.4, 0.4, 0.4});
@@ -17,7 +23,9 @@ Terrain::Terrain(const vec3& center, int size)
     material->setHeightMap(heightMap);
     material->setDiffuseMap(diffuseMap);
 
-    material->setHeightScale(10);
+    heightMap_ = heightMap;
+    
+    material->setHeightScale(heightScale_);
 
     setMaterial(material);
 
@@ -28,3 +36,18 @@ Terrain::~Terrain()
 {
     delete mesh_;
 }
+
+float Terrain::height(float x, float z)
+{
+    assert(heightMap_);
+    
+    vec3 uvw;
+
+    float width = size_ * 2;
+    
+    uvw.setX((x + size_) / width);
+    uvw.setY((z + size_) / width);
+    uvw.setZ(0);
+    
+    return heightMap_->sample(uvw).x() * heightScale_;
+}

src/terrain.h

@@ -6,8 +6,22 @@
 class Terrain : public SceneObject
 {
 public:
-    Terrain(const vec3& center, int size);
+    Terrain(const vec3& center, float size);
     virtual ~Terrain();
+    
+    float height(float x, float z);
+    
+private:
+    // half width of terrain
+    float size_ = 10;
+    
+    // weak reference
+    Texture* heightMap_ = NULL;
+    
+    // TODO temp
+    vec3 center_;
+    
+    float heightScale_ = 1;
 };
 
 #endif // TERRAIN_H

src/texture2d.cpp

@@ -54,8 +54,26 @@ void Texture2D::load(string filename)
 
 vec4 Texture2D::sample(const vec3 &uvw)
 {
-    cout << "1" << endl;
-    return vec4();
+    struct Color32 {
+        uint8_t r;
+        uint8_t g;
+        uint8_t b;
+        uint8_t a;
+    };
+    
+    float u = uvw.x();
+    float v = uvw.y();
+
+    int x = (int)(u * image_->width()) % image_->width();
+    int y = image_->height() - (int)(v * image_->height()) % image_->height() - 1;
+    
+    Color32 *data = (Color32 *)image_->bits();
+    
+    assert(x < image_->width() && x >= 0);
+    assert(y < image_->height() && y >= 0);
+    
+    Color32 color = data[y * image_->width() + x];
+    return vec4(color.r / 255.f, color.g / 255.f, color.b / 255.f, color.a / 255.f);
 }
 
 void Texture2D::apply(DrawContext &context, string name, int binding) const