CubeMap.cpp

#include "CubeMap.h"
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"

#include "Window.h"

CubeMap::CubeMap(std::vector<std::string> faces) {
	//all the vertices of the cube
	std::vector<float> vertices{       
		-1.0f,  1.0f, -1.0f,
		-1.0f, -1.0f, -1.0f,
		 1.0f, -1.0f, -1.0f,
		 1.0f, -1.0f, -1.0f,
		 1.0f,  1.0f, -1.0f,
		-1.0f,  1.0f, -1.0f,

		-1.0f, -1.0f,  1.0f,
		-1.0f, -1.0f, -1.0f,
		-1.0f,  1.0f, -1.0f,
		-1.0f,  1.0f, -1.0f,
		-1.0f,  1.0f,  1.0f,
		-1.0f, -1.0f,  1.0f,

		 1.0f, -1.0f, -1.0f,
		 1.0f, -1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f, -1.0f,
		 1.0f, -1.0f, -1.0f,

		-1.0f, -1.0f,  1.0f,
		-1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f, -1.0f,  1.0f,
		-1.0f, -1.0f,  1.0f,

		-1.0f,  1.0f, -1.0f,
		 1.0f,  1.0f, -1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		-1.0f,  1.0f,  1.0f,
		-1.0f,  1.0f, -1.0f,

		-1.0f, -1.0f, -1.0f,
		-1.0f, -1.0f,  1.0f,
		 1.0f, -1.0f, -1.0f,
		 1.0f, -1.0f, -1.0f,
		-1.0f, -1.0f,  1.0f,
		 1.0f, -1.0f,  1.0f
	};;

	//generate and load the texture
	tex = loadCubemap(faces);

	//Generate buffers
	glGenVertexArrays(1, &vao);
	glGenBuffers(1, &vbo);

	//Bind VAO
	glBindVertexArray(vao);

	//Bind VBO to write data
	glBindBuffer(GL_ARRAY_BUFFER, vbo);
	glBufferData(GL_ARRAY_BUFFER, sizeof(float) * vertices.size(),
		vertices.data(), GL_STATIC_DRAW);
	
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), 0);

	// Unbind from the VBOs.
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	// Unbind from the VAO.
	glBindVertexArray(0);
}

unsigned int CubeMap::loadCubemap(std::vector<std::string> faces)
{
	unsigned int textureID;
	glGenTextures(1, &textureID);
	glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);

	int width, height, nrChannels;
	for (unsigned int i = 0; i < faces.size(); i++)
	{
		unsigned char* data = stbi_load(faces[i].c_str(), &width, &height, &nrChannels, 0);
		if (data)
		{
			glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i,
				0, GL_SRGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data
			);
			stbi_image_free(data);
		}
		else
		{
			std::cout << "Cubemap texture failed to load at path: " << faces[i] << std::endl;
			stbi_image_free(data);
		}
	}
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);

	return textureID;
}

CubeMap::~CubeMap() {
	// Delete the VBOs and the VAO.
	glDeleteBuffers(1, &vbo);
	glDeleteVertexArrays(1, &vao);
}

void CubeMap::draw()
{
	glUniformMatrix4fv(Window::skyProjectionLoc, 1, GL_FALSE, glm::value_ptr(Window::activeScene->activeCamera->projection));
	glUniformMatrix4fv(Window::skyViewLoc, 1, GL_FALSE, glm::value_ptr(glm::mat4(glm::mat3(Window::activeScene->activeCamera->view))));
	glBindVertexArray(vao);
	glActiveTexture(GL_TEXTURE0);
	glBindTexture(GL_TEXTURE_CUBE_MAP, tex);
	glDrawArrays(GL_TRIANGLES, 0, 36);
	glBindVertexArray(0);
}

void CubeMap::update() {

}

unsigned int CubeMap::getTexId() {
	return tex;
}