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#include "texture.h"
#include "lodepng.h"
#include <vector>
#include <cmath>
void graphics::Texture::makePowerOfTwo()
{
// Texture size must be power of two for the primitive OpenGL version this is written for. Find next power of two.
int u2 = 1; while (u2 < m_width) u2 *= 2;
int v2 = 1; while (v2 < m_height) v2 *= 2;
if (u2 == m_width && v2 == m_height)
return;
// Make power of two version of the image.
std::vector<unsigned char> image2(u2 * v2 * 4);
for (int i = 0; i < v2; i++)
for (int j = 0; j < u2; j++)
{
float x = (m_width-1) * j / (float)u2;
float y = (m_height-1) * i / (float)v2;
int x_L = (int)floorf(x);
int x_U = (int)ceilf(x);
int y_L = (int)floorf(y);
int y_U = (int)ceilf(y);
float sx = x - x_L;
float sy = y - y_L;
for (int c = 0; c < 4; c++)
{
float valx1 = (1.0f - sx) * m_buffer[4 * (y_L*m_width + x_L) + c] + sx * m_buffer[4 * (y_L*m_width + x_U) + c];
float valx2 = (1.0f - sx) * m_buffer[4 * (y_U*m_width + x_L) + c] + sx * m_buffer[4 * (y_U*m_width + x_U) + c];
float valy = (1.0f - sy) * valx1 + sy * valx2;
image2[4 * (i*u2 + j) + c] = (unsigned char)roundf(valy);
}
}
m_buffer = std::move(image2);
m_width = u2;
m_height = v2;
}
bool graphics::Texture::load(const std::string & file)
{
unsigned int error = lodepng::decode(m_buffer, m_width, m_height, file.c_str());
return !error;
}
void graphics::Texture::buildGLTexture()
{
glEnable(GL_TEXTURE_2D);
glGenTextures(1, &m_id);
glBindTexture(GL_TEXTURE_2D, m_id);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, 4, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, &m_buffer[0]);
glGenerateMipmap(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, 0);
}
graphics::Texture::Texture(const std::string & filename)
{
m_filename = filename;
if (!load(filename))
return;
makePowerOfTwo();
buildGLTexture();
}
GLuint graphics::TextureManager::getTexture(std::string file)
{
auto iter = textures.find(file);
if (iter != textures.end())
{
return iter->second.getID();
}
else
{
textures.insert(std::make_pair(file, Texture(file)));
}
return GLuint();
}
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