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#include "terrain.h"
#include "math/math_util.h"
#include "math/vector.h"
#include "util/util.h"
#include "renderer/renderer.h"
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <math.h>
#define PLANE_SIZE 128
#define PLANE_MAX_HEIGHT 10
#define NUM_ARRAY_ELEMENTS(a) sizeof(a) / sizeof(*a)
static float GetHeight(int x, int y, SDL_Surface* surface)
{
if(x < 0 || x >= surface->w || y < 0 || y >= surface->h)
return 0.0f;
Uint32 pixel = ( (Uint32*)surface->pixels )[y * surface->w + x];
Uint8 r, g, b;
SDL_GetRGB(pixel, surface->format, &r, &g, &b);
float height = (float)r / 255.0f;
return height * 40.0f;
}
static Vec3 GenerateNomal(int x, int y, SDL_Surface* surface)
{
float hLeft = GetHeight(x-1, y, surface);
float hRight = GetHeight(x+1, y, surface);
float hUp = GetHeight(x, y+1, surface);
float hDown = GetHeight(x, y-1, surface);
Vec3 normal = { hLeft - hRight, 2.0f, hDown - hUp};
return vec3_normalize(&normal);
}
GLfloat Terrain_GetHeightOfTerrain(Terrain *terrain, GLfloat x, GLfloat z)
{
GLfloat terrainX = x - terrain->position.x;
GLfloat terrainZ = z - terrain->position.z;
GLfloat gridSquareSize = (float)terrain->l / ( (float)PLANE_SIZE - 1 );
GLint gridX = (GLint) floor(terrainX / gridSquareSize);
GLint gridZ = (GLint) floor(terrainZ / gridSquareSize);
if(gridX >= PLANE_SIZE - 1 || gridX < 0 || gridZ >= PLANE_SIZE - 1 || gridZ < 0)
{
printf("called\n");
return 0;
}
GLfloat xCoord = fmod(terrainX, gridSquareSize) / gridSquareSize;
GLfloat zCoord = fmod(terrainZ, gridSquareSize) / gridSquareSize;
GLfloat answer;
/* Determine in which triangle of the square are we. "Bary Centric Interpolation"*/
if(xCoord <= (1 - zCoord)){
/* 0, heights[gridX][gridZ], 0) */
Vec3 p1 = { 0, terrain->height[ gridX * PLANE_SIZE + gridZ ], 0 };
/* 1, heights[gridX + 1][gridZ], 0) */
Vec3 p2 = { 1, terrain->height[ (gridX + 1) * PLANE_SIZE + gridZ ], 0};
/* 0, heights[gridX][gridZ + 1], 1) */
Vec3 p3 = { 0, terrain->height[ gridX * PLANE_SIZE + (gridZ + 1) ], 1};
Vec2 pos = {xCoord, zCoord};
answer = baryCentric(&p1, &p2, &p3, &pos);
} else {
/* (1, heights[gridX + 1][gridZ], 0) */
Vec3 p1 = { 1, terrain->height[ (gridX + 1) * PLANE_SIZE + gridZ ], 0 };
/* (1, heights[gridX + 1][gridZ + 1], 1) */
Vec3 p2 = { 1, terrain->height[ (gridX + 1) * PLANE_SIZE + (gridZ + 1) ], 1};
/* (0, heights[gridX][gridZ + 1], 1) */
Vec3 p3 = { 0, terrain->height[ gridX * PLANE_SIZE + (gridZ + 1) ], 1};
Vec2 pos = {xCoord, zCoord};
answer = baryCentric(&p1, &p2, &p3, &pos);
}
return answer;
}
Terrain *Terrain_Create( int w, int l, const char* heightmap_path, Texture *blendmap, TerrainTexturePack *textures )
{
Terrain *terrain = malloc( sizeof(Terrain) );
terrain->height = (GLfloat*) malloc( sizeof(GLfloat) * PLANE_SIZE * PLANE_SIZE);
terrain->blendmap = blendmap;
terrain->w = w; terrain->l = l;
terrain->textures = *textures;
SDL_Surface* surface = IMG_Load(heightmap_path);
if(surface == NULL)
Util_FatalError("Heightmap file could not be loaded\n");
vertex_t data[PLANE_SIZE * PLANE_SIZE];
int x, y;
for(x = 0; x < PLANE_SIZE; x++)
{
for(y = 0; y < PLANE_SIZE; y++)
{
vertex_t* v = &data[y + x * PLANE_SIZE];
v->position = (Vec3){ (float)x / (float)PLANE_SIZE, 0.0f, (float)y / (float)PLANE_SIZE };
/* Heightmap cordinates */
int image_x = v->position.x * surface->w, image_y = v->position.z * surface->h;
v->texCoord = (Vec2){ v->position.x, v->position.z };
GLfloat height = GetHeight(image_x, image_y, surface);
terrain->height[y + x * PLANE_SIZE] = height;
v->position.y = height;
v->position.x *= w;
v->position.z *= l;
v->normal = GenerateNomal(image_x, image_y, surface);
}
}
int runner = 0;
GLushort indices[ (PLANE_SIZE-1) * (PLANE_SIZE-1) * 6 ];
for(x = 0; x < PLANE_SIZE-1; x++)
{
for(y = 0; y < PLANE_SIZE-1; y++)
{
indices[runner++] = PLANE_SIZE * x + y;
indices[runner++] = PLANE_SIZE * x + y + 1;
indices[runner++] = PLANE_SIZE * x + y + PLANE_SIZE;
indices[runner++] = PLANE_SIZE * x + y + 1;
indices[runner++] = PLANE_SIZE * x + y + PLANE_SIZE + 1;
indices[runner++] = PLANE_SIZE * x + y + PLANE_SIZE;
}
}
GLsizeiptr vertexBufferSize = NUM_ARRAY_ELEMENTS(data) * sizeof(vertex_t);
GLsizeiptr indexBufferSize = NUM_ARRAY_ELEMENTS(indices) * sizeof(GLushort);
SDL_FreeSurface(surface);
terrain->mesh = mesh_new(data, vertexBufferSize, indices, indexBufferSize);
return terrain;
}
void Terrain_Destroy( Terrain *terrain )
{
if(terrain->height)
free(terrain->height);
free(terrain);
}
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