Calculate EBO index array, upload data to GPU

src/heightmap.cpp

@@ -5,6 +5,8 @@
 #include <fstream>
 #include <iostream>
 #include <sstream>
+#include <utility>
+#include <algorithm>
 
 Heightmap::Heightmap(std::string filename): _filename(filename) {
 	std::string file_string = "";
@@ -54,8 +56,8 @@ Heightmap::Heightmap(std::string filename): _filename(filename) {
 		_maxZ = max(_data, 2, 3);
 		_zRangeUm = (_maxZ - _minZ) / 10.; //in um
 		/*Throw if _zRange is less than 1 A (i.e. it's probably 0)*/
-		if (_zRange < 1e-4) {
-			throw Nt1100_exception("Heightmap: z range is too close to zero (" + std::to_string(_zRange) + ")");
+		if (_zRangeUm < 1e-4) {
+			throw Nt1100_exception("Heightmap::Heightmap(std::string): z range is too close to zero (" + std::to_string(_zRangeUm) + ")");
 		}
 		/*TODO: Renormalize model coordinates sensible here*/
 		//For now, I just renormalize the z range to [0,1]
@@ -69,6 +71,50 @@ Heightmap::Heightmap(std::string filename): _filename(filename) {
 		glGenBuffers(1, &_vbo);
 		glGenBuffers(1, &_ebo);
 		glGenVertexArrays(1, &_vao);
+
+		/*Calculate EBO indexing array*/
+		std::vector<unsigned> ebo_array;
+		ebo_array.reserve(2 * _data.size()); //rough upper bound
+		//Calculate Ny assuming that _data is crossed column by column
+		_Ny = 0;
+		while (3 * _Ny < _data.size() && _data[3 * _Ny] == _data[0]) {
+			++_Ny;
+		}
+		//Sanity check _Ny
+		if (_Ny < 5 || 3 * _Ny + 10 > _data.size()) {
+			throw Nt1100_exception("Heightmap::Heightmap(std::string): Probably failed to deduce _Ny. Found _Ny=" + std::to_string(_Ny) + ", for _data of size " + std::to_string(_data.size()));
+		}
+		//Deduce _Nx
+		_Nx = _data.size() / 3 / _Ny;
+		if (3 * _Nx * _Ny != _data.size()) {
+			throw Nt1100_exception("Heightmap::Heightmap(std::string): Value of _Nx=" + std::to_string(_Nx) + " or _Ny=" + std::to_string(_Ny) + " is incorrect for _data of size " + std::to_string(_data.size()));
+		}
+		for (unsigned i = 0; i < _Nx - 1; ++i) {
+			for (unsigned j = 0; j < _Ny - 1; ++j) {
+				std::array<std::pair<unsigned, unsigned>, 6> ijs = { { { i, j }, {i, j + 1}, {i + 1, j}, {i + 1, j}, {i + 1, j + 1}, {i, j + 1} } };
+				std::array<unsigned, 6> index_array;
+				std::transform(ijs.begin(), ijs.end(), index_array.begin(), [&](const std::pair<unsigned, unsigned>& p) {return ij2index(p.first, p.second, _Ny); });
+				ebo_array.insert(ebo_array.end(), index_array.begin(), index_array.end());
+			}
+		}
+		/*Upload EBO data*/
+		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _ebo);
+		glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned) * ebo_array.size(), ebo_array.data(), GL_STATIC_DRAW);
+		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
+		/*Upload VBO data*/
+		//Temporarily cast to float
+		std::vector<float> data_float;
+		data_float.reserve(_data.size());
+		data_float.insert(data_float.begin(), _data.begin(), _data.end());
+		glBindBuffer(GL_ARRAY_BUFFER, _vbo);
+		glBufferData(GL_ARRAY_BUFFER, sizeof(float) * data_float.size(), data_float.data(), GL_STATIC_DRAW);
+		/*Setup VAO*/
+		glBindVertexArray(_vao);
+		glBindBuffer(GL_ARRAY_BUFFER, _vbo);
+		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+		glEnableVertexAttribArray(0);
+		glBindVertexArray(0);
+		glBindBuffer(GL_ARRAY_BUFFER, 0);
 		/*TODO: Generate shader, I may want to use a Factory here*/
 
 	}