/**

 * $Id$

 *

 * Standard OpenGL rendering engine. 

 *

 * Copyright (c) 2005 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 <sys/time.h>

#include "display.h"

#include "pvr2/pvr2.h"

#include "pvr2/pvr2mmio.h"

#include "pvr2/scene.h"

#include "pvr2/glutil.h"

#define IS_EMPTY_TILE_LIST(p) ((*((uint32_t *)(video_base+(p))) >> 28) == 0x0F)

int pvr2_poly_depthmode[8] = { GL_NEVER, GL_LESS, GL_EQUAL, GL_LEQUAL,

        GL_GREATER, GL_NOTEQUAL, GL_GEQUAL, 

        GL_ALWAYS };

int pvr2_poly_srcblend[8] = { 

        GL_ZERO, GL_ONE, GL_DST_COLOR, GL_ONE_MINUS_DST_COLOR,

        GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA, 

        GL_ONE_MINUS_DST_ALPHA };

int pvr2_poly_dstblend[8] = {

        GL_ZERO, GL_ONE, GL_SRC_COLOR, GL_ONE_MINUS_SRC_COLOR,

        GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_DST_ALPHA,

        GL_ONE_MINUS_DST_ALPHA };

int pvr2_poly_texblend[4] = {

        GL_REPLACE, 

        GL_MODULATE,  

        GL_DECAL, 

        GL_MODULATE 

};

/**

 * Clip the tile bounds to the clipping plane. 

 * @return TRUE if the tile was not clipped completely.

 */

static gboolean clip_tile_bounds( uint32_t *tile, float *clip )

{

    if( tile[0] < clip[0] ) tile[0] = clip[0];

    if( tile[1] > clip[1] ) tile[1] = clip[1];

    if( tile[2] < clip[2] ) tile[2] = clip[2];

    if( tile[3] > clip[3] ) tile[3] = clip[3];

    return tile[0] < tile[1] && tile[2] < tile[3];

}

void pvr2_scene_load_textures()

{

    int i;

    for( i=0; i < pvr2_scene.poly_count; i++ ) {

        struct polygon_struct *poly = &pvr2_scene.poly_array[i];

        if( POLY1_TEXTURED(poly->context[0]) ) {

            poly->tex_id = texcache_get_texture( poly->context[2],

                    POLY2_TEX_WIDTH(poly->context[1]),

                    POLY2_TEX_HEIGHT(poly->context[1]) );

            if( poly->mod_vertex_index != -1 ) {

                if( pvr2_scene.shadow_mode == SHADOW_FULL ) {

                    poly->mod_tex_id = texcache_get_texture( poly->context[4],

                            POLY2_TEX_WIDTH(poly->context[3]),

                            POLY2_TEX_HEIGHT(poly->context[3]) );

                } else {

                    poly->mod_tex_id = poly->tex_id;

                }

            }

        } else {

            poly->tex_id = -1;

            poly->mod_tex_id = -1;

        }

    }

}

/**

 * Once-off call to setup the OpenGL context.

 */

void pvr2_setup_gl_context()

{

    if( glsl_is_supported() ) {

        if( !glsl_load_shaders( glsl_vertex_shader_src, NULL ) ) {

            WARN( "Unable to load GL shaders" );

        }

    }

    texcache_gl_init(); // Allocate texture IDs

    glCullFace( GL_BACK );

    glEnable( GL_BLEND );

    glEnable( GL_DEPTH_TEST );

    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

#ifdef HAVE_OPENGL_CLAMP_COLOR

    if( isGLExtensionSupported("GL_ARB_color_buffer_float") ) {

        glClampColorARB(GL_CLAMP_VERTEX_COLOR_ARB, GL_FALSE );

        glClampColorARB(GL_CLAMP_FRAGMENT_COLOR_ARB, GL_FALSE );

    }

#endif

    glEnableClientState( GL_COLOR_ARRAY );

    glEnableClientState( GL_VERTEX_ARRAY );

    glEnableClientState( GL_TEXTURE_COORD_ARRAY );

    glEnableClientState( GL_SECONDARY_COLOR_ARRAY );

    glEnableClientState( GL_FOG_COORDINATE_ARRAY_EXT );

    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    glClearDepth(0);

    glClearStencil(0);

}

static void render_set_cull( uint32_t poly1 )

{

    switch( POLY1_CULL_MODE(poly1) ) {

    case CULL_NONE:

    case CULL_SMALL:

        glDisable( GL_CULL_FACE );

        break;

    case CULL_CCW:

        glEnable( GL_CULL_FACE );

        glFrontFace( GL_CW );

        break;

    case CULL_CW:

        glEnable( GL_CULL_FACE );

        glFrontFace( GL_CCW );

        break;

    }   

}    

/**

 * Setup the basic context that's shared between normal and modified modes -

 * depth, culling

 */

static void render_set_base_context( uint32_t poly1 )

{

    glDepthFunc( POLY1_DEPTH_MODE(poly1) );

    glDepthMask( POLY1_DEPTH_WRITE(poly1) ? GL_TRUE : GL_FALSE );

    render_set_cull( poly1 );

    glShadeModel( POLY1_SHADE_MODEL(poly1) );

    if( POLY1_SPECULAR(poly1) ) {

        glEnable(GL_COLOR_SUM);

    } else {

        glDisable(GL_COLOR_SUM);

    }

}

/**

 * Setup the texture/shading settings (TSP) which vary between mod/unmod modes.

 */

static void render_set_tsp_context( uint32_t poly1, uint32_t poly2, uint32_t texture )

{

    if( POLY1_TEXTURED(poly1) ) {

         glEnable(GL_TEXTURE_2D);

         glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, pvr2_poly_texblend[POLY2_TEX_BLEND(poly2)] );

         if( POLY2_TEX_CLAMP_U(poly2) ) {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP );

         } else if( POLY2_TEX_MIRROR_U(poly2) ) {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT_ARB );

         } else {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT );

         }       

         if( POLY2_TEX_CLAMP_V(poly2) ) {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP );

         } else if( POLY2_TEX_MIRROR_V(poly2) ) {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT_ARB );

         } else {

             glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT );

         }

     } else {

         glDisable( GL_TEXTURE_2D );

     }

     switch( POLY2_FOG_MODE(poly2) ) {

     case PVR2_POLY_FOG_LOOKUP:

         glFogfv( GL_FOG_COLOR, pvr2_scene.fog_lut_colour );

         glEnable( GL_FOG );

         break;

     case PVR2_POLY_FOG_VERTEX:

         if( POLY1_SPECULAR(poly1) ) {

             glFogfv( GL_FOG_COLOR, pvr2_scene.fog_vert_colour );

             glEnable( GL_FOG );

             break;

         } /* else fallthrough */

     default:

         glDisable( GL_FOG );

     }

     int srcblend = POLY2_SRC_BLEND(poly2);

     int destblend = POLY2_DEST_BLEND(poly2);

     glBlendFunc( srcblend, destblend );

     if( POLY2_SRC_BLEND_TARGET(poly2) || POLY2_DEST_BLEND_TARGET(poly2) ) {

         WARN( "Accumulation buffer not supported" );

     }   

}

/**

 * Setup the GL context for the supplied polygon context.

 * @param context pointer to 3 or 5 words of polygon context

 * @param modified boolean flag indicating that the modified

 *  version should be used, rather than the normal version.

 */

void render_set_context( uint32_t *context, int render_mode )

{

    uint32_t poly1 = context[0], poly2, texture;

    if( render_mode == RENDER_FULLMOD ) {

        poly2 = context[3];

        texture = context[4];

    } else {

        poly2 = context[1];

        texture = context[2];

    }

    render_set_base_context(poly1);

    render_set_tsp_context(poly1,poly2,texture);

}

static void gl_render_poly( struct polygon_struct *poly )

{

    if( poly->tex_id != -1 ) {

        glBindTexture(GL_TEXTURE_2D, poly->tex_id);

    }

    if( poly->mod_vertex_index == -1 ) {

        glDisable( GL_STENCIL_TEST );

        render_set_context( poly->context, RENDER_NORMAL );

        glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index, poly->vertex_count );

    }  else {

        glEnable( GL_STENCIL_TEST );

        render_set_base_context( poly->context[0] );

        render_set_tsp_context( poly->context[0], poly->context[1], poly->context[2] );

        glStencilFunc(GL_EQUAL, 0, 2);

        glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index, poly->vertex_count );

        if( pvr2_scene.shadow_mode == SHADOW_FULL ) {

            if( poly->mod_tex_id != -1 ) {

                glBindTexture(GL_TEXTURE_2D, poly->mod_tex_id);

            }

            render_set_tsp_context( poly->context[0], poly->context[3], poly->context[4] );

        }

        glStencilFunc(GL_EQUAL, 2, 2);

        glDrawArrays(GL_TRIANGLE_STRIP, poly->mod_vertex_index, poly->vertex_count );

    }

}

static void gl_render_bkgnd( struct polygon_struct *poly )

{

    if( poly->tex_id != -1 ) {

        glBindTexture(GL_TEXTURE_2D, poly->tex_id);

    }

    render_set_context( poly->context, RENDER_NORMAL );

    glDisable( GL_DEPTH_TEST );

    glDisable( GL_CULL_FACE );

    glBlendFunc( GL_ONE, GL_ZERO );

    glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index, poly->vertex_count );

    glEnable( GL_CULL_FACE );

    glEnable( GL_DEPTH_TEST );

}

void gl_render_tilelist( pvraddr_t tile_entry )

{

    uint32_t *tile_list = (uint32_t *)(video_base+tile_entry);

    int strip_count;

    struct polygon_struct *poly;

    if( !IS_TILE_PTR(tile_entry) )

        return;

    while(1) {

        uint32_t entry = *tile_list++;

        switch( entry >> 28 ) {

        case 0x0F:

            return; // End-of-list

        case 0x0E:

            tile_list = (uint32_t *)(video_base + (entry&0x007FFFFF));

            break;

        case 0x08: case 0x09: case 0x0A: case 0x0B:

            strip_count = ((entry >> 25) & 0x0F)+1;

            poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

            while( strip_count > 0 ) {

                assert( poly != NULL );

                gl_render_poly( poly );

                poly = poly->next;

                strip_count--;

            }

            break;

        default:

            if( entry & 0x7E000000 ) {

                poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

                gl_render_poly( poly );

            }

        }

    }       

}

/**

 * Render the tilelist with depthbuffer updates only. 

 */

void gl_render_tilelist_depthonly( pvraddr_t tile_entry )

{

    uint32_t *tile_list = (uint32_t *)(video_base+tile_entry);

    int strip_count;

    struct polygon_struct *poly;

    if( !IS_TILE_PTR(tile_entry) )

        return;

    glDisable( GL_TEXTURE_2D );

    glDisable( GL_FOG );

    glDisable( GL_COLOR_SUM );

    while(1) {

        uint32_t entry = *tile_list++;

        switch( entry >> 28 ) {

        case 0x0F:

            return; // End-of-list

        case 0x0E:

            tile_list = (uint32_t *)(video_base + (entry&0x007FFFFF));

            break;

        case 0x08: case 0x09: case 0x0A: case 0x0B:

            strip_count = ((entry >> 25) & 0x0F)+1;

            poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

            while( strip_count > 0 ) {

                render_set_base_context(poly->context[0]);

                glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index, poly->vertex_count );

                poly = poly->next;

                strip_count--;

            }

            break;

        default:

            if( entry & 0x7E000000 ) {

                poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

                render_set_base_context(poly->context[0]);

                glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index, poly->vertex_count );

            }

        }

    }           

}

static void drawrect2d( uint32_t tile_bounds[], float z )

{

    glBegin( GL_QUADS );

    glVertex3f( tile_bounds[0], tile_bounds[2], z );

    glVertex3f( tile_bounds[1], tile_bounds[2], z );

    glVertex3f( tile_bounds[1], tile_bounds[3], z );

    glVertex3f( tile_bounds[0], tile_bounds[3], z );

    glEnd();

}

void gl_render_modifier_polygon( struct polygon_struct *poly, uint32_t tile_bounds[] )

{

    /* A bit of explanation:

     * In theory it works like this: generate a 1-bit stencil for each polygon

     * volume, and then AND or OR it against the overall 1-bit tile stencil at 

     * the end of the volume. 

     * 

     * The implementation here uses a 2-bit stencil buffer, where each volume

     * is drawn using only stencil bit 0, and then a 'flush' polygon is drawn

     * to update bit 1 accordingly and clear bit 0.

     * 

     * This could probably be more efficient, but at least it works correctly 

     * now :)

     */

    render_set_cull(poly->context[0]);

    glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index, poly->vertex_count );

    int poly_type = POLY1_VOLUME_MODE(poly->context[0]);

    if( poly_type == PVR2_VOLUME_REGION0 ) {

        /* 00 => 00

         * 01 => 00

         * 10 => 10

         * 11 => 00

         */

        glStencilMask( 0x03 );

        glStencilFunc(GL_EQUAL, 0x02, 0x03);

        glStencilOp(GL_ZERO, GL_KEEP, GL_KEEP);

        glDisable( GL_CULL_FACE );

        glDisable( GL_DEPTH_TEST );

        drawrect2d( tile_bounds, pvr2_scene.bounds[4] );

        glEnable( GL_DEPTH_TEST );

        glStencilMask( 0x01 );

        glStencilFunc( GL_ALWAYS, 0, 1 );

        glStencilOp( GL_KEEP,GL_INVERT, GL_KEEP ); 

    } else if( poly_type == PVR2_VOLUME_REGION1 ) {

        /* This is harder with the standard stencil ops - do it in two passes

         * 00 => 00 | 00 => 10

         * 01 => 10 | 01 => 10

         * 10 => 10 | 10 => 00

         * 11 => 10 | 11 => 10

         */

        glStencilMask( 0x02 );

        glStencilOp( GL_INVERT, GL_INVERT, GL_INVERT );

        glDisable( GL_CULL_FACE );

        glDisable( GL_DEPTH_TEST );

        drawrect2d( tile_bounds, pvr2_scene.bounds[4] );

        glStencilMask( 0x03 );

        glStencilFunc( GL_NOTEQUAL,0x02, 0x03);

        glStencilOp( GL_ZERO, GL_REPLACE, GL_REPLACE );

        drawrect2d( tile_bounds, pvr2_scene.bounds[4] );

        glEnable( GL_DEPTH_TEST );

        glStencilMask( 0x01 );

        glStencilFunc( GL_ALWAYS, 0, 1 );

        glStencilOp( GL_KEEP,GL_INVERT, GL_KEEP );         

    }

}

void gl_render_modifier_tilelist( pvraddr_t tile_entry, uint32_t tile_bounds[] )

{

    uint32_t *tile_list = (uint32_t *)(video_base+tile_entry);

    int strip_count;

    struct polygon_struct *poly;

    if( !IS_TILE_PTR(tile_entry) )

        return;

    glDisable( GL_TEXTURE_2D );

    glDisable( GL_FOG );

    glDisable( GL_COLOR_SUM );

    glDisable( GL_CULL_FACE );

    glEnable( GL_STENCIL_TEST );

    glEnable( GL_DEPTH_TEST );

    glDepthFunc( GL_LEQUAL );

    glStencilFunc( GL_ALWAYS, 0, 1 );

    glStencilOp( GL_KEEP,GL_INVERT, GL_KEEP ); 

    glStencilMask( 0x01 );

    glDepthMask( GL_FALSE );

    while(1) {

        uint32_t entry = *tile_list++;

        switch( entry >> 28 ) {

        case 0x0F:

            glDepthMask( GL_TRUE );

            glStencilOp( GL_KEEP, GL_KEEP, GL_KEEP );

            return; // End-of-list

        case 0x0E:

            tile_list = (uint32_t *)(video_base + (entry&0x007FFFFF));

            break;

        case 0x08: case 0x09: case 0x0A: case 0x0B:

            strip_count = ((entry >> 25) & 0x0F)+1;

            poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

            while( strip_count > 0 ) {

                gl_render_modifier_polygon( poly, tile_bounds );

                poly = poly->next;

                strip_count--;

            }

            break;

        default:

            if( entry & 0x7E000000 ) {

                poly = pvr2_scene.buf_to_poly_map[entry&0x000FFFFF];

                gl_render_modifier_polygon( poly, tile_bounds );

            }

        }

    }

}

/**

 * Render the currently defined scene in pvr2_scene

 */

void pvr2_scene_render( render_buffer_t buffer )

{

    /* Scene setup */

    struct timeval start_tv, tex_tv, end_tv;

    gettimeofday(&start_tv, NULL);

    display_driver->set_render_target(buffer);

    pvr2_check_palette_changed();

    pvr2_scene_load_textures();

    gettimeofday( &tex_tv, NULL );

    uint32_t ms = (tex_tv.tv_sec - start_tv.tv_sec) * 1000 +

    (tex_tv.tv_usec - start_tv.tv_usec)/1000;

    DEBUG( "Scene setup in %dms", ms );

    /* Setup view projection matrix */

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    float nearz = pvr2_scene.bounds[4];

    float farz = pvr2_scene.bounds[5];

    if( nearz == farz ) {

        farz*= 4.0;

    }

    glOrtho( 0, pvr2_scene.buffer_width, pvr2_scene.buffer_height, 0, 

             -farz, -nearz );

    float alphaRef = ((float)(MMIO_READ(PVR2, RENDER_ALPHA_REF)&0xFF)+1)/256.0;

    glAlphaFunc( GL_GEQUAL, alphaRef );

    /* Clear the buffer (FIXME: May not want always want to do this) */

    glDisable( GL_SCISSOR_TEST );

    glDepthMask( GL_TRUE );

    glStencilMask( 0x03 );

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT );

    /* Setup vertex array pointers */

    glVertexPointer(3, GL_FLOAT, sizeof(struct vertex_struct), &pvr2_scene.vertex_array[0].x);

    glColorPointer(4, GL_FLOAT, sizeof(struct vertex_struct), &pvr2_scene.vertex_array[0].rgba[0]);

    glTexCoordPointer(2, GL_FLOAT, sizeof(struct vertex_struct), &pvr2_scene.vertex_array[0].u);

    glSecondaryColorPointerEXT(3, GL_FLOAT, sizeof(struct vertex_struct), pvr2_scene.vertex_array[0].offset_rgba );

    glFogCoordPointerEXT(GL_FLOAT, sizeof(struct vertex_struct), &pvr2_scene.vertex_array[0].offset_rgba[3] );

    glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);

    glFogi(GL_FOG_MODE, GL_LINEAR);

    glFogf(GL_FOG_START, 0.0);

    glFogf(GL_FOG_END, 1.0);

    /* Turn on the shaders (if available) */

    glsl_enable_shaders(TRUE);

    /* Render the background */

    gl_render_bkgnd( pvr2_scene.bkgnd_poly );

    glEnable( GL_SCISSOR_TEST );

    /* Process the segment list */

    struct tile_segment *segment = pvr2_scene.segment_list;

    do {

        int tilex = SEGMENT_X(segment->control);

        int tiley = SEGMENT_Y(segment->control);

        uint32_t tile_bounds[4] = { tilex << 5, (tilex+1)<<5, tiley<<5, (tiley+1)<<5 };

        if( !clip_tile_bounds(tile_bounds, pvr2_scene.bounds) ) {

            continue; // fully clipped, skip tile

        }

        /* Clip to the visible part of the tile */

        glScissor( tile_bounds[0], pvr2_scene.buffer_height-tile_bounds[3], 

                   tile_bounds[1]-tile_bounds[0], tile_bounds[3] - tile_bounds[2] );

        if( display_driver->capabilities.stencil_bits >= 2 && 

                IS_TILE_PTR(segment->opaquemod_ptr) &&

                !IS_EMPTY_TILE_LIST(segment->opaquemod_ptr) ) {

            /* Don't do this unless there's actually some shadow polygons */

            /* Use colormask instead of drawbuffer for simplicity */

            glColorMask( GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE );

            gl_render_tilelist_depthonly(segment->opaque_ptr);

            gl_render_modifier_tilelist(segment->opaquemod_ptr, tile_bounds);

            glClear( GL_DEPTH_BUFFER_BIT );

            glColorMask( GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE );

        }

        gl_render_tilelist(segment->opaque_ptr);

        if( IS_TILE_PTR(segment->punchout_ptr) ) {

            glEnable(GL_ALPHA_TEST );

            render_autosort_tile(segment->punchout_ptr, RENDER_NORMAL );

            glDisable(GL_ALPHA_TEST );

        }

        glDisable( GL_STENCIL_TEST );

        if( IS_TILE_PTR(segment->trans_ptr) ) {

            if( pvr2_scene.sort_mode == SORT_NEVER || 

                    (pvr2_scene.sort_mode == SORT_TILEFLAG && (segment->control&SEGMENT_SORT_TRANS))) {

                gl_render_tilelist(segment->trans_ptr);

            } else {

                render_autosort_tile(segment->trans_ptr, RENDER_NORMAL );

            }

        }

    } while( !IS_LAST_SEGMENT(segment++) );

    glDisable( GL_SCISSOR_TEST );

    glsl_enable_shaders(FALSE);

    gettimeofday( &end_tv, NULL );

    ms = (end_tv.tv_sec - tex_tv.tv_sec) * 1000 +

    (end_tv.tv_usec - tex_tv.tv_usec)/1000;

    DEBUG( "Scene render in %dms", ms );

}