MTexture.h

#ifndef MAYA_API_MTexture
#define MAYA_API_MTexture

//-
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// MTexture.h

// DESCRIPTION: Texture object, that can be mipmapped. Eventually, this
//                              class will likely end up in the Maya API.
//
// AUTHOR: Christian Laforte
//

#include <maya/MImage.h>
#include <maya/MString.h>
#include <assert.h>

#if defined(OSMac_MachO_)
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>
#else
#include <GL/gl.h>
#include <GL/glu.h>
#endif

int highestPowerOf2(int num);

class TexObj
{
public:
        TexObj(GLenum target = GL_TEXTURE_2D)
        {
                assert(glGetError() == GL_NO_ERROR);

                // Get a texture identifier.
                glGenTextures(1, &fTextureNum);
                assert(glGetError() == GL_NO_ERROR);

                fTarget = target;

                // Set up default values for the texture parameters.
                // They are the same as the OpenGL default.
                fMinFilterParam = GL_NEAREST;
                fMagFilterParam = GL_LINEAR;
                fWrapSParam = GL_REPEAT;
                fWrapTParam = GL_REPEAT;
        }

        ~TexObj()
        {
                glDeleteTextures(1, &fTextureNum);
        }

        void bind()
        {
                assert(glGetError() == GL_NO_ERROR);

                // Bind the texture.
                glBindTexture(fTarget, fTextureNum);
                assert(glGetError() == GL_NO_ERROR);

                // Set up the texture parameters.
                glTexParameteri(fTarget, GL_TEXTURE_MIN_FILTER, fMinFilterParam);
                assert(glGetError() == GL_NO_ERROR);
                glTexParameteri(fTarget, GL_TEXTURE_MAG_FILTER, fMagFilterParam);
                assert(glGetError() == GL_NO_ERROR);
                glTexParameteri(fTarget, GL_TEXTURE_WRAP_S, fWrapSParam);
                assert(glGetError() == GL_NO_ERROR);
                glTexParameteri(fTarget, GL_TEXTURE_WRAP_T, fWrapTParam);
                assert(glGetError() == GL_NO_ERROR);
        }

        void parameter(GLenum pname, GLint param)
        {
                switch (pname)
                {
                case GL_TEXTURE_MIN_FILTER:     fMinFilterParam = param;        break;
                case GL_TEXTURE_MAG_FILTER:     fMagFilterParam = param;        break;
                case GL_TEXTURE_WRAP_S:         fWrapSParam = param;            break;
                case GL_TEXTURE_WRAP_T:         fWrapTParam = param;            break;
                }
        }

private:
        GLenum fTarget;

        // Various parameters. See glTexParameterf() in MSDN for more info.
        GLint fMinFilterParam;
        GLint fMagFilterParam;
        GLint fWrapSParam;
        GLint fWrapTParam;
        
        GLuint fTextureNum;
};

class MTexture
{
public:
        enum Type
        {
                RGBA,
                HILO,
                NMAP
        };

        MTexture();

        ~MTexture()
        {
                if (m_levels)
                {
                        for (unsigned int i=0; i < m_numLevels; i++)
                        {
                                if (m_levels[i])
                                {
                                        delete [] m_levels[i];
                                        m_levels[i] = NULL;
                                }
                        }
                        
                        delete [] m_levels;
                }
        }

        bool set(MImage &image, Type type, bool mipmapped = true, GLenum target = GL_TEXTURE_2D);

        // This function assumes that the file texture is square, and
        // that its dimensions are exponents of 2.
        bool load(MString filename, Type type, bool mipmapped = true, GLenum target = GL_TEXTURE_2D);
        
        bool specify(GLenum target);

        // Returns 1 if no mipmapping, >1 otherwise.
        unsigned int levels() { return m_numLevels; }

        bool bind();

        unsigned char* fetch(unsigned int s, unsigned int t, unsigned int level = 0)
        {
                // Verify that the mipmap level exists.
                if (level > m_numLevels || m_levels == NULL || m_levels[level] == NULL)
                        return NULL;
                
                return internalFetch(s, t, level);
        }
        
        inline bool square()
        {
                return m_width == m_height;
        }

        inline bool mipmapped()
        {
                return levels() > 1;
        }

        // Return the width of a specific mipmap level.
        // If level == 0, return the width of the base level (source image).
        // Width is always >= 1, to prevent non-square textures from having zero-sized levels.
        inline unsigned int width(unsigned int level = 0)
        {
                unsigned int w = m_width >> level;
                if (w > 0)
                        return w;
                else
                        return 1;
        }
        
        inline unsigned int height(unsigned int level = 0)
        {
                unsigned int h = m_height >> level;
                if (h > 0)
                        return h;
                else
                        return 1;
        }

protected:

        inline unsigned char* internalFetch(unsigned int s, unsigned int t, unsigned int level)
        {
                assert((s >= 0) && (s < width(level)));
                assert((t >= 0) && (t < height(level)));
                return m_levels[level] + 4 * ((width(level) * t) + s);
        }


private:

        // Fairly permanent variables   
        unsigned int m_width, m_height;
        Type m_type;
        TexObj m_texObj;
        bool m_mipmapped;
        
        // Pyramid levels (assumes 4 bytes per pixel for now)
        unsigned char **m_levels;
        unsigned int m_numLevels;       // Number of mipmaps + base texture

        // Cached variables (Depend on previous private variables)
        GLint           m_internalFormat;
        GLenum          m_format;
        GLenum          m_componentFormat;
};


#endif // MAYA_API_MTexture