From 197f20b5d4db937029f7b585be23ee7fe5da66dc Mon Sep 17 00:00:00 2001
From: Eleni Maria Stea <estea@igalia.com>
Date: Wed, 16 Aug 2017 16:25:47 +0300
Subject: [PATCH] added function that procedurally generates heightfield
 replaced jpg images with hdr

---
 external/gph-math |    2 +-
 external/libimago |    2 +-
 src/main.cc       |    2 +-
 src/meshgen.cc    |   97 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/meshgen.h     |    2 ++
 src/terrain.cc    |   39 +++++++++++++++++++++
 src/terrain.h     |   38 +++++++++++++++++++++
 7 files changed, 178 insertions(+), 4 deletions(-)

diff --git a/external/gph-math b/external/gph-math
index 4c82eda..54ac4cb 160000
--- a/external/gph-math
+++ b/external/gph-math
@@ -1 +1 @@
-Subproject commit 4c82eda2dcba00a4998cfd60a13330dc793b16ca
+Subproject commit 54ac4cbc3b08744e570a53e7f1a8ba862ea87b80
diff --git a/external/libimago b/external/libimago
index d7e3914..843ac48 160000
--- a/external/libimago
+++ b/external/libimago
@@ -1 +1 @@
-Subproject commit d7e3914d568a9e397b1bcd11b3722a84e7f4334e
+Subproject commit 843ac48c7cd58166bb9dc0d49097c1b0ae7e2029
diff --git a/src/main.cc b/src/main.cc
index 7061bb6..166b467 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -138,7 +138,7 @@ static bool init(Gfx_API api)
 	}
 
 	gskybox = gfx_create_texture();
-	gskybox->load("data/cubemap/cubemap.jpg");
+	gskybox->load("data/cubemap/cubemap.hdr");
 	rground->set_sky_tex(gskybox);
 
 	rcow = new Renderer;
diff --git a/src/meshgen.cc b/src/meshgen.cc
index fb4fae2..ff7906d 100644
--- a/src/meshgen.cc
+++ b/src/meshgen.cc
@@ -120,4 +120,99 @@ void gen_geosphere(Mesh *mesh, float rad, int subdiv, bool hemi)
 		mesh->indices[i] = i;
 	}
 	mesh->update_vertex_data();
-}
\ No newline at end of file
+}
+
+// ------ heightfield ------
+
+static Vec3 hfield_vertex(float u, float v, float h, float xsz,
+		float ysz, float height)
+{
+	float x = u * xsz - xsz / 2.0;
+	float y = h * height;
+	float z = v * ysz - ysz / 2.0;
+
+	return Vec3(x, y, z);
+}
+
+void gen_heightfield(Mesh *mesh, float xsz, float ysz, float height, int usub,
+		int vsub, float (*calc_height)(float u, float v, void *ptr), void *ptr)
+{
+	/* 
+	usub and vsub is the number of subdivision at each axis
+	(heightfield = grid) 
+	*/
+	if(usub < 1)
+		usub = 1;
+
+	if(vsub < 1)
+		vsub = 1;
+
+	int num_uvertices = usub + 1;
+	int num_vvertices = vsub + 1;
+
+	int num_quads = usub * vsub;
+	int num_triangles = num_quads * 2;
+
+	int num_vertices = num_uvertices * num_vvertices;
+
+	mesh->vertices.resize(num_vertices);
+	mesh->normals.resize(num_vertices);
+	mesh->tex_coords.resize(num_vertices);
+	mesh->indices.resize(num_triangles * 3);
+
+	int vidx = 0;
+	float du = 1.0 / (float)num_uvertices;
+	float dv = 1.0 / (float)num_vvertices;
+
+	for(int i=0; i<num_vvertices; i++) {
+		float v = (float)i / (float)num_vvertices;
+		for(int j=0; j<num_uvertices; j++) {
+			float u = (float)j / (float)num_uvertices;
+			Vec3 vtx = hfield_vertex(u, v, calc_height(u, v, ptr), xsz, ysz, height);
+
+			/* calculating normal with forward differences:
+			slopes in x, z, axis */
+
+			Vec3 tangent = hfield_vertex(u + du, v, calc_height(u + du, v, ptr),
+					xsz, ysz, height) - vtx;
+
+			Vec3 bitangent = hfield_vertex(u, v + dv, calc_height(u, v + dv, ptr),
+					xsz, ysz, height) - vtx;
+
+			Vec3 normal = normalize(cross(tangent, bitangent));
+
+			mesh->vertices[vidx] = vtx;
+			mesh->normals[vidx] = normal;
+			mesh->tex_coords[vidx] = Vec2(u, v);
+
+			vidx++;
+		}
+	}
+
+	/*
+		indices: 
+	*/
+	uint16_t *iptr = &mesh->indices[0];
+
+	for(int i=0; i<vsub; i++) {
+		for(int j=0; j<usub; j++) {
+			int a = num_vvertices * i + j;
+			int b = a + 1;
+			int d = num_vvertices * (i + 1) + j;
+			int c = d + 1;
+
+			/* 1st triangle */
+
+			*iptr++ = a;
+			*iptr++ = b;
+			*iptr++ = c;
+
+			/* 2nd triangle */
+
+			*iptr++ = c;
+			*iptr++ = d;
+			*iptr++ = a;
+		}
+	}
+	mesh->update_vertex_data();
+}
diff --git a/src/meshgen.h b/src/meshgen.h
index bcd09ae..81880f6 100644
--- a/src/meshgen.h
+++ b/src/meshgen.h
@@ -7,5 +7,7 @@ class Mesh;
 
 /* generates geodesic sphere: if hemi is true we only gen the hemisphere */
 void gen_geosphere(Mesh *mesh, float rad, int subdiv, bool hemi = false);
+void gen_heightfield(Mesh *mesh, float xsz, float ysz, float height, int usub,
+		int vsub, float (*calc_height)(float u, float v, void *ptr), void *ptr);
 
 #endif	// MESHGEN_H_
diff --git a/src/terrain.cc b/src/terrain.cc
index e69de29..6bfabe8 100644
--- a/src/terrain.cc
+++ b/src/terrain.cc
@@ -0,0 +1,39 @@
+#include "camera.h"
+#include "image.h"
+#include "scene.h"
+#include "terrain.h"
+
+Terrain::Terrain() {}
+
+Terrain::~Terrain()
+{
+}
+
+bool Terrain::generate(const TerrainParams &params)
+{
+	// if(xsz <= 0 || ysz <=0) {
+	// 	fprintf(stderr, "Invalid terrain size.\n");
+	// 	return false;
+	// }
+
+	// if(xtiles <= 0 || ytiles <= 0) {
+	// 	fprintf(stderr, "Invalid number of terrain tiles.\n");
+	// 	return false;
+	// }
+
+	// if(tiles)
+	// 	tiles.clear();
+
+	// int tsz = xtiles * ytiles;
+	// tiles.resize(tsz);
+
+	// for(int i=0; i<tsz; i++) {
+
+	// }
+	return true;
+}
+
+Scene *Terrain::get_visible(const Camera *camera) const
+{
+	return 0;
+}
diff --git a/src/terrain.h b/src/terrain.h
index d6f4844..f2ecd69 100644
--- a/src/terrain.h
+++ b/src/terrain.h
@@ -1,6 +1,44 @@
 #ifndef TERRAIN_H_
 #define TERRAIN_H_
 
+class Camera;
+class Image;
+class Scene;
 
+// terrain 8a ftiaxnei skini k taisma renderer
+class TerrainTile {
+private:
+	Mesh *mesh;
+
+};
+
+/* parameters needed in terrain generation */
+
+struct TerrainParams {
+	float xsz; /* terrain size in x axis */
+	float ysz; /* terrain size in y axis */
+	float max_height; /* max height of the heightfield */
+	int xtiles; /* number of tiles in x axis */
+	int ytiles; /* number of tiles in y axis */
+	int tile_usub;
+	int tile_vsub;
+	int num_octaves; /* Perlin noise sums */
+	Image *coarse_heightmap; /* mask for low detail heightmap */
+};
+
+class Terrain {
+private:
+	TerrainParams params;
+	mutable Scene *vis_scene; /* set of visible tiles returned by get_visible */
+
+	std::vector<TerrainTile> tiles;
+	
+public:
+	Terrain();
+	~Terrain();
+
+	bool generate(const TerrainParams &params);
+	Scene *get_visible(const Camera *camera) const;
+};
 
 #endif // TERRAIN_H_
\ No newline at end of file
-- 
1.7.10.4