Histogram Struct Reference

Inheritance diagram for Histogram:

Public Member Functions
	Histogram (const char *filename)
int	init ()
	a deriver pour creer les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.
int	quit ()
	a deriver pour detruire les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.
int	render ()
	a deriver pour afficher les objets. renvoie 1 pour continuer, 0 pour fermer l'application.
	Histogram (const char *filename)
int	init ()
	a deriver pour creer les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.
int	quit ()
	a deriver pour detruire les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.
int	render ()
	a deriver pour afficher les objets. renvoie 1 pour continuer, 0 pour fermer l'application.
	Histogram (const char *filename)
int	init ()
	a deriver pour creer les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.
int	quit ()
	a deriver pour detruire les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.
int	render ()
	a deriver pour afficher les objets. renvoie 1 pour continuer, 0 pour fermer l'application.
Public Member Functions inherited from App
	App (const int width, const int height, const int major=3, const int minor=3, const int samples=0)
	constructeur, dimensions de la fenetre et version d'openGL.
virtual int	update (const float time, const float delta)
	a deriver et redefinir pour animer les objets en fonction du temps.
int	run ()
	execution de l'application.

Public Attributes
ImageData	m_image
GLuint	m_program
GLuint	m_time_query
GLuint	m_histogram
GLuint	m_texture
GLint	m_threads [3]

Additional Inherited Members
Protected Member Functions inherited from App
virtual int	prerender ()
virtual int	postrender ()
void	vsync_off ()
Protected Attributes inherited from App
Window	m_window
Context	m_context
bool	sync

Detailed Description

Definition at line 13 of file tuto_histogram1_compute.cpp.

Constructor & Destructor Documentation

Histogram() [1/3]

Histogram::Histogram ( const char * filename )

inline

Definition at line 15 of file tuto_histogram1_compute.cpp.

                                      : App(1024, 640, 4,3)
    {
        m_image= read_image_data(filename);
    }

Histogram() [2/3]

Histogram::Histogram ( const char * filename )

inline

Definition at line 15 of file tuto_histogram2_compute.cpp.

                                      : App(1024, 640, 4,3)
    {
        m_image= read_image_data(filename);
    }

Histogram() [3/3]

Histogram::Histogram ( const char * filename )

inline

Definition at line 15 of file tuto_histogram_compute.cpp.

                                      : App(1024, 640, 4,3)
    {
        m_image= read_image_data(filename);
    }

Member Function Documentation

init() [1/3]

int Histogram::init ( )

inlinevirtual

a deriver pour creer les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.

Implements App.

Definition at line 20 of file tuto_histogram1_compute.cpp.

    {
        if(m_image.pixels.size() == 0)
            // pas d'image
            return -1;
        
        // cree la texture pour stocker l'image
        GLenum data_type= GL_UNSIGNED_BYTE;
        GLenum data_format= GL_RGBA;
        if(m_image.channels == 1)
            data_format= GL_RED;
        else if(m_image.channels == 2)
            data_format= GL_RG;
        else if(m_image.channels == 3)
            data_format= GL_RGB;
        
        glGenTextures(1, &m_texture);
        glBindTexture(GL_TEXTURE_2D, m_texture);
        glTexImage2D(GL_TEXTURE_2D, 0,
            GL_RGBA8, m_image.width, m_image.height, 0,
            data_format, data_type, m_image.data());
        
        // pas la peine de construire les mipmaps, le shader ne va ecrire que le mipmap 0
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
        
        // cree le buffer pour stocker l'histogramme
        glGenBuffers(1, &m_histogram);
        glBindBuffer(GL_SHADER_STORAGE_BUFFER, m_histogram);
        glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(int) * 16, nullptr, GL_STATIC_COPY);
        
        m_program= read_program("gkit2_tutos/M2/histogram1.glsl");
        program_print_errors(m_program);
        
        glGetProgramiv(m_program, GL_COMPUTE_WORK_GROUP_SIZE, m_threads);
        
        // mesure temps gpu
        glGenQueries(1, &m_time_query);
        
        // histogramme cpu pour comparer...
        {
            auto start= std::chrono::high_resolution_clock::now();
            
            int histogram[16]= { 0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0 };
            for(unsigned y= 0; y < m_image.height; y++)
            for(unsigned x= 0; x < m_image.width; x++)
            {
                unsigned offset= m_image.offset(x, y);
                int r= m_image.pixels[offset];
                int g= m_image.pixels[offset+1];
                int b= m_image.pixels[offset+2];
                int bin= 15 * (r+g+b) / (255*3);
                histogram[bin]++;
            }
            
            auto stop= std::chrono::high_resolution_clock::now();
            int cpu_time= std::chrono::duration_cast<std::chrono::microseconds>(stop - start).count();
            
            for(int i= 0; i < 16; i++)
                printf("bin %d: %d pixels, %d%%\n", i, histogram[i], 100*histogram[i] / (m_image.width * m_image.height));
            
            printf("cpu %dus\n", cpu_time);
        }
        
        return 1;
    }

quit() [1/3]

int Histogram::quit ( )

inlinevirtual

a deriver pour detruire les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.

Implements App.

Definition at line 86 of file tuto_histogram1_compute.cpp.

    {
        release_program(m_program);
        glDeleteBuffers(1, &m_histogram);
        glDeleteTextures(1, &m_texture);
        glDeleteQueries(1, &m_time_query);
        return 0;
    }

render() [1/3]

int Histogram::render ( )

inlinevirtual

a deriver pour afficher les objets. renvoie 1 pour continuer, 0 pour fermer l'application.

Implements App.

Definition at line 95 of file tuto_histogram1_compute.cpp.

    {
        glViewport(0, 0, window_width(), window_height());
        glClear(GL_COLOR_BUFFER_BIT);
        
        glUseProgram(m_program);
        
        // storage buffer 0
        glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, m_histogram);
        // remet a zero l'histogramme
        glClearBufferData(GL_SHADER_STORAGE_BUFFER, GL_R32UI, GL_RED_INTEGER, GL_UNSIGNED_INT, 0);
        
        // image texture 0, ecriture seule, mipmap 0 + format rgba8 classique
        glBindImageTexture(0, m_texture, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA8);
        // configurer le shader
        program_uniform(m_program, "image", 0);
 
        int nx= m_image.width / m_threads[0];
        int ny= m_image.height / m_threads[1];
        // on suppose que les dimensions de l'image sont multiples de 8...
        // sinon calculer correctement le nombre de groupes pour x et y. 
        
        glBeginQuery(GL_TIME_ELAPSED, m_time_query);
        {
            // go !!
            //~ for(int i= 0; i < 100; i++)     // eventuellement recommencer plein de fois pour stabiliser les frequences du gpu...
            glDispatchCompute(nx, ny, 1);
            
            // attendre le resultat
            glMemoryBarrier(GL_ALL_BARRIER_BITS);
        }
        glEndQuery(GL_TIME_ELAPSED);
        
        // relire le buffer resultat
        int histogram[16];
        {
            // creer un buffer temporaire pour le transfert depuis le buffer resultat
            GLuint buffer= 0;
            glGenBuffers(1, &buffer);
            glBindBuffer(GL_COPY_READ_BUFFER, buffer);
            glBufferData(GL_COPY_READ_BUFFER, sizeof(int) * 16, nullptr, GL_DYNAMIC_READ);
            
            // copie les resultats
            glCopyBufferSubData(GL_SHADER_STORAGE_BUFFER, GL_COPY_READ_BUFFER, 0, 0, sizeof(int) * 16);
            
            // recupere les resultats depuis le buffer intermediaire
            glGetBufferSubData(GL_COPY_READ_BUFFER, 0, sizeof(int) * 16, histogram);
            
            // detruit le buffer intermediaire
            glDeleteBuffers(1, &buffer);
        }
        
        for(int i= 0; i < 16; i++)
            printf("bin %d: %d pixels, %d%%\n", i, histogram[i], 100*histogram[i] / (m_image.width * m_image.height));
        
        printf("\n%dx%d groups, %d threads\n", nx, ny, nx*ny*m_threads[0]*m_threads[1]);
        
        // attendre le resultat de la requete
        GLint64 gpu_time= 0;
        glGetQueryObjecti64v(m_time_query, GL_QUERY_RESULT, &gpu_time);
        //~ gpu_time/= 100;
        printf("gpu  %02dms %03dus\n\n", int(gpu_time / 1000000), int((gpu_time / 1000) % 1000));    
        
        return 0;       // une seule fois
        //~ return 1;   // recommencer jusqu'a la fermeture de la fenetre...
    }

init() [2/3]

int Histogram::init ( )

inlinevirtual

a deriver pour creer les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.

Implements App.

Definition at line 20 of file tuto_histogram2_compute.cpp.

    {
        if(m_image.pixels.size() == 0)
            // pas d'image
            return -1;
        
        // cree la texture pour stocker l'image
        GLenum data_type= GL_UNSIGNED_BYTE;
        GLenum data_format= GL_RGBA;
        if(m_image.channels == 1)
            data_format= GL_RED;
        else if(m_image.channels == 2)
            data_format= GL_RG;
        else if(m_image.channels == 3)
            data_format= GL_RGB;
        //~ else
            //~ data_format= GL_RGBA;
        
        glGenTextures(1, &m_texture);
        glBindTexture(GL_TEXTURE_2D, m_texture);
        glTexImage2D(GL_TEXTURE_2D, 0,
            GL_RGBA8, m_image.width, m_image.height, 0,
            data_format, data_type, m_image.data());
        
        // pas la peine de construire les mipmaps, le shader ne va ecrire que le mipmap 0
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
        
        // cree le buffer pour stocker l'histogramme
        glGenBuffers(1, &m_histogram);
        glBindBuffer(GL_SHADER_STORAGE_BUFFER, m_histogram);
        glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(int) * 16, nullptr, GL_STATIC_COPY);
        
        m_program= read_program("gkit2_tutos/M2/histogram2.glsl");
        program_print_errors(m_program);
        
        glGetProgramiv(m_program, GL_COMPUTE_WORK_GROUP_SIZE, m_threads);
        
        // mesure temps gpu
        glGenQueries(1, &m_time_query);
        
        // histogramme cpu pour comparer...
        {
            auto start= std::chrono::high_resolution_clock::now();
            
            int histogram[16]= { 0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0 };
            for(unsigned y= 0; y < m_image.height; y++)
            for(unsigned x= 0; x < m_image.width; x++)
            {
                unsigned offset= m_image.offset(x, y);
                int r= m_image.pixels[offset];
                int g= m_image.pixels[offset+1];
                int b= m_image.pixels[offset+2];
                int bin= 15 * (r+g+b) / (255*3);
                histogram[bin]++;
            }
            
            auto stop= std::chrono::high_resolution_clock::now();
            int cpu_time= std::chrono::duration_cast<std::chrono::microseconds>(stop - start).count();
            
            for(int i= 0; i < 16; i++)
                printf("bin %d: %d pixels, %d%%\n", i, histogram[i], 100*histogram[i] / (m_image.width * m_image.height));
            
            printf("cpu %dus\n", cpu_time);
        }
        
        return 1;
    }

quit() [2/3]

int Histogram::quit ( )

inlinevirtual

a deriver pour detruire les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.

Implements App.

Definition at line 88 of file tuto_histogram2_compute.cpp.

    {
        release_program(m_program);
        glDeleteBuffers(1, &m_histogram);
        glDeleteTextures(1, &m_texture);
        glDeleteQueries(1, &m_time_query);
        return 0;
    }

render() [2/3]

int Histogram::render ( )

inlinevirtual

a deriver pour afficher les objets. renvoie 1 pour continuer, 0 pour fermer l'application.

Implements App.

Definition at line 97 of file tuto_histogram2_compute.cpp.

    {
        glViewport(0, 0, window_width(), window_height());
        glClear(GL_COLOR_BUFFER_BIT);
        
        glUseProgram(m_program);
        
        // storage buffer 0
        glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, m_histogram);
        // remet a zero l'histogramme
        glClearBufferData(GL_SHADER_STORAGE_BUFFER, GL_R32UI, GL_RED_INTEGER, GL_UNSIGNED_INT, 0);
        
        // image texture 0, ecriture seule, mipmap 0 + format rgba8 classique
        glBindImageTexture(0, m_texture, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA8);
        // configurer le shader
        program_uniform(m_program, "image", 0);
 
        int nx= m_image.width / m_threads[0];
        int ny= m_image.height / m_threads[1];
        // on suppose que les dimensions de l'image sont multiples de 8...
        // sinon calculer correctement le nombre de groupes pour x et y. 
        
        glBeginQuery(GL_TIME_ELAPSED, m_time_query);
        {
            // go !!
            //~ for(int i= 0; i < 100; i++)     // eventuellement recommencer plein de fois pour stabiliser les frequences du gpu...
            glDispatchCompute(nx, ny, 1);
            
            // attendre le resultat
            glMemoryBarrier(GL_ALL_BARRIER_BITS);
        }
        glEndQuery(GL_TIME_ELAPSED);
        
        // relire le buffer resultat
        int histogram[16];
        {
            // creer un buffer temporaire pour le transfert depuis le buffer resultat
            GLuint buffer= 0;
            glGenBuffers(1, &buffer);
            glBindBuffer(GL_COPY_READ_BUFFER, buffer);
            glBufferData(GL_COPY_READ_BUFFER, sizeof(int) * 16, nullptr, GL_DYNAMIC_READ);
            
            // copie les resultats
            glCopyBufferSubData(GL_SHADER_STORAGE_BUFFER, GL_COPY_READ_BUFFER, 0, 0, sizeof(int) * 16);
            
            // recupere les resultats depuis le buffer intermediaire
            glGetBufferSubData(GL_COPY_READ_BUFFER, 0, sizeof(int) * 16, histogram);
            
            // detruit le buffer intermediaire
            glDeleteBuffers(1, &buffer);
        }
        
        for(int i= 0; i < 16; i++)
            printf("bin %d: %d pixels, %d%%\n", i, histogram[i], 100*histogram[i] / (m_image.width * m_image.height));
        
        printf("\n%dx%d groups, %d threads\n", nx, ny, nx*ny*m_threads[0]*m_threads[1]);
        
        // attendre le resultat de la requete
        GLint64 gpu_time= 0;
        glGetQueryObjecti64v(m_time_query, GL_QUERY_RESULT, &gpu_time);
        //~ gpu_time/= 100;
        printf("gpu  %02dms %03dus\n\n", int(gpu_time / 1000000), int((gpu_time / 1000) % 1000));    
        
        return 0;       // une seule fois
        //~ return 1;   // recommencer jusqu'a la fermeture de la fenetre...
    }

init() [3/3]

int Histogram::init ( )

inlinevirtual

a deriver pour creer les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.

Implements App.

Definition at line 20 of file tuto_histogram_compute.cpp.

    {
        if(m_image.pixels.size() == 0)
            // pas d'image
            return -1;
        
        // cree la texture pour stocker l'image
        GLenum data_type= GL_UNSIGNED_BYTE;
        GLenum data_format= GL_RGBA;
        if(m_image.channels == 1)
            data_format= GL_RED;
        else if(m_image.channels == 2)
            data_format= GL_RG;
        else if(m_image.channels == 3)
            data_format= GL_RGB;
        //~ else
            //~ data_format= GL_RGBA;
        
        glGenTextures(1, &m_texture);
        glBindTexture(GL_TEXTURE_2D, m_texture);
        glTexImage2D(GL_TEXTURE_2D, 0,
            GL_RGBA8, m_image.width, m_image.height, 0,
            data_format, data_type, m_image.data());
        
        // pas la peine de construire les mipmaps, le shader ne va ecrire que le mipmap 0
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
        
        // cree le buffer pour stocker l'histogramme
        glGenBuffers(1, &m_histogram);
        glBindBuffer(GL_SHADER_STORAGE_BUFFER, m_histogram);
        glBufferData(GL_SHADER_STORAGE_BUFFER, sizeof(int) * 16, nullptr, GL_STATIC_COPY);
        
        m_program= read_program("gkit2_tutos/M2/histogram.glsl");
        program_print_errors(m_program);
        
        glGetProgramiv(m_program, GL_COMPUTE_WORK_GROUP_SIZE, m_threads);
        
        // mesure temps gpu
        glGenQueries(1, &m_time_query);
        
        // histogramme cpu pour comparer...
        {
            auto start= std::chrono::high_resolution_clock::now();
            
            int histogram[16]= { 0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0,  0, 0, 0, 0 };
            for(unsigned y= 0; y < m_image.height; y++)
            for(unsigned x= 0; x < m_image.width; x++)
            {
                unsigned offset= m_image.offset(x, y);
            #if 0
                float r= float(m_image.pixels[offset]) / 255;
                float g= float(m_image.pixels[offset+1]) / 255;
                float b= float(m_image.pixels[offset+2]) / 255;
                float grey= (r+g+b) / 3;
                int bin= int(15 * grey);
            #else
                // nettement plus rapide ...
                int r= m_image.pixels[offset];
                int g= m_image.pixels[offset+1];
                int b= m_image.pixels[offset+2];
                int bin= 15 * (r+g+b) / (255*3);                
            #endif
                histogram[bin]++;
            }
            
            auto stop= std::chrono::high_resolution_clock::now();
            int cpu_time= std::chrono::duration_cast<std::chrono::microseconds>(stop - start).count();
            
            for(int i= 0; i < 16; i++)
                printf(" [%d] %d pixels, %d%%\n", i, histogram[i], 100*histogram[i] / (m_image.width * m_image.height));
            
            printf("cpu %dus\n", cpu_time);
        }
        
        return 1;
    }

quit() [3/3]

int Histogram::quit ( )

inlinevirtual

a deriver pour detruire les objets openGL. renvoie -1 pour indiquer une erreur, 0 sinon.

Implements App.

Definition at line 97 of file tuto_histogram_compute.cpp.

    {
        release_program(m_program);
        glDeleteBuffers(1, &m_histogram);
        glDeleteTextures(1, &m_texture);
        glDeleteQueries(1, &m_time_query);
        return 0;
    }

render() [3/3]

int Histogram::render ( )

inlinevirtual

a deriver pour afficher les objets. renvoie 1 pour continuer, 0 pour fermer l'application.

Implements App.

Definition at line 106 of file tuto_histogram_compute.cpp.

    {
        glViewport(0, 0, window_width(), window_height());
        glClear(GL_COLOR_BUFFER_BIT);
        
        glUseProgram(m_program);
        
        // storage buffer 0
        glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, m_histogram);
        // remet a zero l'histogramme
        glClearBufferData(GL_SHADER_STORAGE_BUFFER, GL_R32UI, GL_RED_INTEGER, GL_UNSIGNED_INT, 0);
        
        // image texture 0, ecriture seule, mipmap 0 + format rgba8 classique
        glBindImageTexture(0, m_texture, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA8);
        // configurer le shader
        program_uniform(m_program, "image", 0);
 
        int nx= m_image.width / m_threads[0] / 4;
        int ny= m_image.height / m_threads[1] / 4;
        // on suppose que les dimensions de l'image sont multiples de 8*4...
        // sinon calculer correctement le nombre de groupes pour x et y. 
        
        glBeginQuery(GL_TIME_ELAPSED, m_time_query);
        {
            // go !!
            //~ for(int i= 0; i < 100; i++)     // eventuellement recommencer plein de fois pour stabiliser les frequences du gpu...
            glDispatchCompute(nx, ny, 1);
            
            // attendre le resultat
            glMemoryBarrier(GL_ALL_BARRIER_BITS);
        }
        glEndQuery(GL_TIME_ELAPSED);
        
        // relire le buffer resultat
        int histogram[16];
    #if 1
        {
            // creer un buffer temporaire pour le transfert depuis le buffer resultat
            GLuint buffer= 0;
            glGenBuffers(1, &buffer);
            glBindBuffer(GL_COPY_READ_BUFFER, buffer);
            glBufferData(GL_COPY_READ_BUFFER, sizeof(int) * 16, nullptr, GL_DYNAMIC_READ);
            
            // copie les resultats
            glCopyBufferSubData(GL_SHADER_STORAGE_BUFFER, GL_COPY_READ_BUFFER, 0, 0, sizeof(int) * 16);
            
            // recupere les resultats depuis le buffer intermediaire
            glGetBufferSubData(GL_COPY_READ_BUFFER, 0, sizeof(int) * 16, histogram);
            
            // detruit le buffer intermediaire
            glDeleteBuffers(1, &buffer);
        }
    #else
        glGetBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, sizeof(int) * 16, histogram);
    #endif
        
        for(int i= 0; i < 16; i++)
            printf(" [%d] %d pixels, %d%%\n", i, histogram[i], 100*histogram[i] / (m_image.width * m_image.height));
        
        printf("\n%dx%d groups, %d threads\n", nx, ny, nx*ny*m_threads[0]*m_threads[1]);
        // attendre le resultat de la requete
        GLint64 gpu_time= 0;
        glGetQueryObjecti64v(m_time_query, GL_QUERY_RESULT, &gpu_time);
        //~ gpu_time/= 100;
        printf("gpu  %02dms %03dus\n\n", int(gpu_time / 1000000), int((gpu_time / 1000) % 1000));    
        
        return 0;       // une seule fois
        //~ return 1;   // recommencer jusqu'a la fermeture de la fenetre...
    }

Member Data Documentation

m_image

ImageData Histogram::m_image

Definition at line 162 of file tuto_histogram1_compute.cpp.

m_program

GLuint Histogram::m_program

Definition at line 163 of file tuto_histogram1_compute.cpp.

m_time_query

GLuint Histogram::m_time_query

Definition at line 164 of file tuto_histogram1_compute.cpp.

m_histogram

GLuint Histogram::m_histogram

Definition at line 165 of file tuto_histogram1_compute.cpp.

m_texture

GLuint Histogram::m_texture

Definition at line 166 of file tuto_histogram1_compute.cpp.

m_threads

GLint Histogram::m_threads

Definition at line 167 of file tuto_histogram1_compute.cpp.

---

The documentation for this struct was generated from the following files:

• gkit2_tutos/M2/tuto_histogram1_compute.cpp
• gkit2_tutos/M2/tuto_histogram2_compute.cpp
• gkit2_tutos/M2/tuto_histogram_compute.cpp