engineer-thesis-WUT/Engine/engine/textures.cpp

#ifndef TEXTURES_CPP
#define TEXTURES_CPP
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include "stb_image.h"
#include "textures.hpp"

void setTextureSCoordinate(const GLenum textureTarget, const GLint sCoordinateOption, const float* borderColor) 
{
    // https://registry.khronos.org/OpenGL-Refpages/gl4/html/glTexParameter.xhtml
    // first argument is texture target (by default we work with 2D textures so it will be GL_TEXTURE_2D)
    // second argument is what option we want to set and for which texture axis (s, t or r)
    // Third argument is texture wrapping mode 
    glTexParameteri(textureTarget, GL_TEXTURE_WRAP_S, sCoordinateOption);
    if(sCoordinateOption == GL_CLAMP_TO_BORDER && borderColor != NULL) 
    {
        // if we use GL_CLAMP_TO_BORDER all of the space that is not occupied by texture will be occupied by color
        // we pass the color we want to use in float array (RGB + transparency)
        glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);
    }
}

void setTextureTCoordinate(const GLenum textureTarget, const GLint tCoordinateOption, const float* borderColor) 
{
    // for comments concerning glTexParameteri and glTexParameterfv go to setTextureSCoordinate function
    if(textureTarget == GL_TEXTURE_2D || textureTarget == GL_TEXTURE_3D) 
    {
        glTexParameteri(textureTarget, GL_TEXTURE_WRAP_T, tCoordinateOption);
        if(tCoordinateOption == GL_CLAMP_TO_BORDER && borderColor != NULL) 
        {
            glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);
        }
    }
}

void setTextureRCoordinate(const GLenum textureTarget, const GLint rCoordinateOption, const float* borderColor) 
{
    // for comments concerning glTexParameteri and glTexParameterfv go to setTextureSCoordinate function
    if(textureTarget == GL_TEXTURE_3D)
    {
        glTexParameteri(textureTarget, GL_TEXTURE_WRAP_R, rCoordinateOption);
        if(rCoordinateOption == GL_CLAMP_TO_BORDER && borderColor != NULL) 
        {
            glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);
        }
    }
}

// Coordinate options can be: GL_REPEAT, GL_MIRRORED_REPEAT, GL_CLAMP_TO_EDGE, GL_CLAMP_TO_BORDER
// s t r are equivalent to x y z 
void setTextureParametersINT(const GLenum textureTarget, const GLint sCoordinateOption, const GLint tCoordinateOption, const GLint rCoordinateOption, const float* borderColor) 
{
    setTextureSCoordinate(textureTarget, sCoordinateOption, borderColor);
    setTextureTCoordinate(textureTarget, tCoordinateOption, borderColor);
    setTextureRCoordinate(textureTarget, rCoordinateOption, borderColor);
}

void setTextureFilteringAndMipMap(const GLenum textureTarget, const GLenum filterType, const GLint textureFilteringMethod, const GLint mipMapFilteringMethod)
{
    // mipMapFilteringMethod can be equal to: GL_NEAREST_MIPMAP_NEAREST, GL_LINEAR_MIPMAP_NEAREST, GL_NEAREST_MIPMAP_LINEAR, GL_LINEAR_MIPMAP_LINEAR
    // NEAREST_MIPMAP - take nearest mipmap to match pixel size 
    // LINEAR_MIPMAP - interpolate between two mipmaps that match the size of a pixel
    // NEAREST (at the end) - samples texture based on nearest neighbor interpolation  
    // LINEAR (at the end) - samples texture using linear interpolation
    // setting anything else than GL_TEXTURE_MIN_FILTER as a second parameter results in GL_INVALID_ENUM error
    glTexParameteri(textureTarget, GL_TEXTURE_MIN_FILTER, mipMapFilteringMethod);
    // https://registry.khronos.org/OpenGL-Refpages/gl4/html/glTexParameter.xhtml
    // first argument is texture target (by default we work with 2D textures so it will be GL_TEXTURE_2D)
    // second argument is specifying whether this filter works for magnifying textures GL_TEXTURE_MAG_FILTER or minifying GL_TEXTURE_MIN_FILTER
    // third argument is how we should magnify/minify textures, whether we should choose the color of pixel closest to the coordinates GL_NEAREST (default)
    // or should we blend the neighboring pixels and choose blended color GL_LINEAR
    glTexParameteri(textureTarget, filterType, textureFilteringMethod);
}


#endif // TEXTURES_CPP