/**

 * $Id$

 *

 * GLSL wrapper code to hide the differences between the different gl/sl APIs.

  *

 * Copyright (c) 2007-2010 Nathan Keynes.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */

#include <assert.h>

#include "lxdream.h"

#include "display.h"

#include "pvr2/glutil.h"

#define MAX_ERROR_BUF 4096

#define INVALID_SHADER 0

#define INVALID_PROGRAM 0

#ifdef HAVE_OPENGL_SHADER_ARB

typedef GLhandleARB gl_program_t;

typedef GLhandleARB gl_shader_t;

#else

typedef GLuint gl_program_t;

typedef GLuint gl_shader_t;

#endif

gboolean glsl_is_supported();

gl_shader_t glsl_create_vertex_shader( const char *source );

gl_shader_t glsl_create_fragment_shader( const char *source );

gl_program_t glsl_create_program( gl_shader_t *shaderv );

void glsl_use_program(gl_program_t program);

void glsl_destroy_shader(gl_shader_t shader);

void glsl_destroy_program(gl_program_t program);

#ifdef HAVE_OPENGL_SHADER_ARB

gboolean glsl_is_supported()

{

    return isGLExtensionSupported("GL_ARB_fragment_shader") &&

    isGLExtensionSupported("GL_ARB_vertex_shader") &&

    isGLExtensionSupported("GL_ARB_shading_language_100");

}

const char *glsl_get_version()

{

    return glGetString(GL_SHADING_LANGUAGE_VERSION_ARB);

}

void glsl_print_error( char *msg, GLhandleARB obj )

{

    char buf[MAX_ERROR_BUF];

    GLsizei length;

    glGetInfoLogARB( obj, sizeof(buf), &length, buf );

    ERROR( "%s: %s", msg, buf );

}

gboolean glsl_check_shader_error( char *msg, GLhandleARB obj )

{

    GLint value;

    glGetObjectParameterivARB(obj, GL_OBJECT_COMPILE_STATUS_ARB, &value);

    if( value == 0 ) {

        glsl_print_error(msg, obj);

        return FALSE;

    }

    return TRUE;

}

gboolean glsl_check_program_error( char *msg, GLhandleARB obj )

{

    if( glGetError() != GL_NO_ERROR ) {

        glsl_print_error(msg, obj);

    }

    return TRUE;

}

gl_shader_t glsl_create_vertex_shader( const char *source )

{

    gboolean ok;

    gl_shader_t shader = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);

    glShaderSourceARB( shader, 1, &source, NULL );

    glCompileShaderARB(shader);

    ok = glsl_check_shader_error("Failed to compile vertex shader", shader);

    if( !ok ) {

        glDeleteObjectARB(shader);

        return INVALID_SHADER;

    } else {

        return shader;

    }

}

gl_shader_t glsl_create_fragment_shader( const char *source )

{

    gboolean ok;

    gl_shader_t shader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);

    glShaderSourceARB( shader, 1, &source, NULL );

    glCompileShaderARB(shader);

    ok = glsl_check_shader_error("Failed to compile fragment shader", shader);

    if( !ok ) {

        glDeleteObjectARB(shader);

        return INVALID_SHADER;

    } else {

        return shader;

    }

}

gl_program_t glsl_create_program( gl_shader_t *shaderv )

{

    gboolean ok;

    unsigned i;

    gl_program_t program = glCreateProgramObjectARB();

    for( i=0; shaderv[i] != INVALID_SHADER; i++ ) {

        glAttachObjectARB(program, shaderv[i]);

    }

    glLinkProgramARB(program);

    ok = glsl_check_program_error( "Failed to link shader program", program );

    if( !ok ) {

        glDeleteObjectARB(program);

        return INVALID_PROGRAM;

    } else {

        return program;

    }

}

void glsl_use_program(gl_program_t program)

{

    glUseProgramObjectARB(program);

    glsl_check_program_error( "Failed to activate shader program", program );

}

void glsl_destroy_shader(gl_shader_t shader)

{

    glDeleteObjectARB(shader);

}

void glsl_destroy_program(gl_program_t program)

{

    glDeleteObjectARB(program);

}

#elif HAVE_OPENGL_SHADER

gboolean glsl_is_supported()

{

    return isGLExtensionSupported("GL_ARB_fragment_shader") &&

    isGLExtensionSupported("GL_ARB_vertex_shader") &&

    isGLExtensionSupported("GL_ARB_shading_language_100");

}

const char *glsl_get_version()

{

    return glGetString(GL_SHADING_LANGUAGE_VERSION);

}

gboolean glsl_check_shader_error( char *msg, GLuint shader )

{

    GLint value;

    glGetShaderiv( shader, GL_COMPILE_STATUS, &value );

    if( value == 0 ) {

        char buf[MAX_ERROR_BUF];

        GLsizei length;

        glGetShaderInfoLog( shader, sizeof(buf), &length, buf );

        ERROR( "%s: %s", msg, buf );

        return FALSE;

    }

    return TRUE;

}

gboolean glsl_check_program_error( char *msg, GLuint program )

{

    if( glGetError() != GL_NO_ERROR ) {

        char buf[MAX_ERROR_BUF];

        GLsizei length;

        glGetProgramInfoLog( program, sizeof(buf), &length, buf );

        ERROR( "%s: %s", msg, buf );

        return FALSE;

    }

    return TRUE;

}

gl_shader_t glsl_create_vertex_shader( const char *source )

{

    gboolean ok;

    gl_shader_t shader = glCreateShader(GL_VERTEX_SHADER);

    glShaderSource( shader, 1, &source, NULL );

    glCompileShader(shader);

    ok = glsl_check_shader_error( "Failed to compile vertex shader", glsl_vert_shader );

    if( !ok ) {

        glDeleteShader(shader);

        return INVALID_SHADER;

    } else {

        return shader;

    }

}

gl_shader_t glsl_create_fragment_shader( const char *source )

{

    gboolean ok;

    gl_shader_t shader = glCreateShader(GL_FRAGMENT_SHADER);

    glShaderSource( shader, 1, &source, NULL );

    glCompileShader(shader);

    ok = glsl_check_shader_error( "Failed to compile fragment shader", glsl_frag_shader );

    if( !ok ) {

        glDeleteShader(shader);

        return INVALID_SHADER;

    } else {

        return shader;

    }

}

gl_program_t glsl_create_program( gl_shader_t *shaderv )

{

    gboolean ok;

    unsigned i;

    gl_program_t program = glCreateProgram();

    for( i=0; shaderv[i] != INVALID_SHADER; i++ ) {

        glAttachShader(program, shaderv[i]);

    }

    glLinkProgram(program);

    ok = glsl_check_program_error( "Failed to link shader program", program );

    if( !ok ) {

        glDeleteProgram(program);

        return INVALID_PROGRAM;

    } else {

        return program;

    }

}

void glsl_use_program(gl_program_t program)

{

    glUseProgram(program);

}

void glsl_destroy_shader(gl_shader_t shader)

{

    glDeleteShader(shader);

}

void glsl_destroy_program(gl_program_t program)

{

    glDeleteProgram(program);

}

#else

gboolean glsl_is_supported()

{

    return FALSE;

}

int glsl_get_version()

{

    return 0;

}

gl_shader_t glsl_create_vertex_shader( const char *source )

{

    return 0;

}

gl_shader_t glsl_create_fragment_shader( const char *source )

{

    return 0;

}

gl_program_t glsl_create_program( gl_shader_t vertex, gl_shader_t fragment )

{

    return 0;

}

void glsl_use_program(gl_program_t program)

{

}

void glsl_destroy_shader(gl_shader_t shader)

{

}

void glsl_destroy_program(gl_program_t program)

{

}

#endif

/****************************************************************************/

/* Pull in the auto-generated shader definitions */

#include "pvr2/shaders.def"

static gl_program_t program_array[GLSL_NUM_PROGRAMS];

gboolean glsl_load_shaders()

{

    gl_shader_t shader_array[GLSL_NUM_SHADERS];

    gboolean ok = TRUE;

    unsigned i, j;

    for( i=0; i<GLSL_NUM_SHADERS; i++ )

        shader_array[i] = INVALID_SHADER;

    for( i=0; i<GLSL_NUM_PROGRAMS; i++ )

        program_array[i] = INVALID_PROGRAM;

    /* Compile the shader fragments */

    for( i=0; shader_source[i].type != GLSL_NO_SHADER; i++ ) {

        gl_shader_t shader = INVALID_SHADER;

        switch(shader_source[i].type) {

        case GLSL_VERTEX_SHADER:

            shader = glsl_create_vertex_shader(shader_source[i].source);

            break;

        case GLSL_FRAGMENT_SHADER:

            shader = glsl_create_fragment_shader(shader_source[i].source);

            break;

        }

        if( shader == INVALID_SHADER ) {

            ok = FALSE;

            break;

        } else {

            shader_array[i] = shader;

        }

    }

    /* Link the programs */

    if(ok) for( i=0; program_list[i][0] != GLSL_NO_SHADER; i++ ) {

        gl_shader_t shaderv[GLSL_NUM_SHADERS+1];

        for( j=0; program_list[i][j] != GLSL_NO_SHADER; j++ ) {

            shaderv[j] = shader_array[program_list[i][j]];

        }

        shaderv[j] = INVALID_SHADER;

        gl_program_t program = glsl_create_program(shaderv);

        if( program == INVALID_PROGRAM ) {

            ok = FALSE;

            break;

        } else {

            program_array[i] = program;

        }

    }

    /**

     * Destroy the compiled fragments (the linked programs don't need them

     * anymore)

     */

    for( i=0; i<GLSL_NUM_SHADERS; i++ ) {

        if( shader_array[i] != INVALID_SHADER )

            glsl_destroy_shader(shader_array[i]);

    }

    /**

     * If we errored, delete the programs. It's all or nothing.

     */

    if( !ok ) {

        glsl_unload_shaders();

        return FALSE;

    }

    return TRUE;

}

void glsl_unload_shaders()

{

    unsigned i;

    for( i=0; i<GLSL_NUM_PROGRAMS; i++ ) {

        if( program_array[i] != INVALID_PROGRAM ) {

            glsl_destroy_program(program_array[i]);

            program_array[i] = INVALID_PROGRAM;

        }

    }

}

gboolean glsl_set_shader(unsigned i)

{

    assert( i >= 0 && i <= GLSL_LAST_PROGRAM );

    if( program_array[i] != INVALID_PROGRAM ) {

        glsl_use_program(program_array[i]);

        return TRUE;

    } else {

        return FALSE;

    }

}

void glsl_clear_shader()

{

    glsl_use_program(0);

}