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// ----------------------------------------------------------------
// From Game Programming in C++ by Sanjay Madhav
// Copyright (C) 2017 Sanjay Madhav. All rights reserved.
// Released under the BSD License
// See LICENSE in root directory for full details.
// ----------------------------------------------------------------
#include "Texture.h"
#include <SOIL/SOIL.h>
#include <GL/glew.h>
#include <SDL/SDL.h>
Texture::Texture()
:mTextureID(0)
,mHeight(0)
Texture::~Texture()
bool Texture::Load(const std::string& fileName)
	int channels = 0;
	unsigned char* image = SOIL_load_image(fileName.c_str(),
										   &mWidth, &mHeight, &channels, SOIL_LOAD_AUTO);
	if (image == nullptr)
		SDL_Log("SOIL failed to load image %s: %s", fileName.c_str(), SOIL_last_result());
		return false;
	int format = GL_RGB;
	if (channels == 4)
		format = GL_RGBA;
	glGenTextures(1, &mTextureID);
	glBindTexture(GL_TEXTURE_2D, mTextureID);
	glTexImage2D(GL_TEXTURE_2D, 0, format, mWidth, mHeight, 0, format,
				 GL_UNSIGNED_BYTE, image);
	SOIL_free_image_data(image);
	// Generate mipmaps for texture
	glGenerateMipmap(GL_TEXTURE_2D);
	// Enable linear filtering
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	// Enable anisotropic filtering, if supported
	if (GLEW_EXT_texture_filter_anisotropic)
		// Get the maximum anisotropy value
		GLfloat largest;
		glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &largest);
		// Enable it
		glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, largest);
	return true;
void Texture::Unload()
	glDeleteTextures(1, &mTextureID);
void Texture::CreateFromSurface(SDL_Surface* surface)
	mWidth = surface->w;
	mHeight = surface->h;
	// Generate a GL texture
	glGenTextures(1, &mTextureID);
	glBindTexture(GL_TEXTURE_2D, mTextureID);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, mWidth, mHeight, 0, GL_BGRA,
				 GL_UNSIGNED_BYTE, surface->pixels);
	// Use linear filtering
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
void Texture::CreateForRendering(int width, int height, unsigned int format)
	mWidth = width;
	mHeight = height;
	// Create the texture id
	glGenTextures(1, &mTextureID);
	glBindTexture(GL_TEXTURE_2D, mTextureID);
	// Set the image width/height with null initial data
	glTexImage2D(GL_TEXTURE_2D, 0, format, mWidth, mHeight, 0, GL_RGB,
		GL_FLOAT, nullptr);
	// For a texture we'll render to, just use nearest neighbor
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
void Texture::SetActive(int index)
	glActiveTexture(GL_TEXTURE0 + index);
	glBindTexture(GL_TEXTURE_2D, mTextureID);

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