/**

  * $Id$

  *

  * 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/glutil.h"

 #include "pvr2/scene.h"

 #include "pvr2/tileiter.h"

 #define IS_EMPTY_TILE_LIST(p) ((*((uint32_t *)(pvr2_main_ram+(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 

 };

 static gboolean have_shaders = FALSE;

 static int currentTexId = -1;

 static inline void bind_texture(int texid)

 {

     if( currentTexId != texid ) {

         currentTexId = texid;

         glBindTexture(GL_TEXTURE_2D, texid);

     }

 }

 /**

  * 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];

 }

 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();

 }

 static void pvr2_scene_load_textures()

 {

     int i;

     texcache_begin_scene( MMIO_READ( PVR2, RENDER_PALETTE ) & 0x03,

                          (MMIO_READ( PVR2, RENDER_TEXSIZE ) & 0x003F) << 5 );

     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[1], poly->context[2] );

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

                 if( pvr2_scene.shadow_mode == SHADOW_FULL ) {

                     poly->mod_tex_id = texcache_get_texture( poly->context[3], poly->context[4] );

                 } else {

                     poly->mod_tex_id = poly->tex_id;

                 }

             }

         } else {

             poly->tex_id = 0;

             poly->mod_tex_id = 0;

         }

     }

 }

 /**

  * Once-off call to setup the OpenGL context.

  */

 void pvr2_setup_gl_context()

 {

     if( glsl_is_supported() && isGLMultitextureSupported() ) {

         if( !glsl_load_shaders( ) ) {

             WARN( "Unable to load GL shaders" );

         } else {

             have_shaders = TRUE;

         }

     }

     texcache_gl_init(); // Allocate texture IDs

     glDisable( GL_CULL_FACE );

     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);

     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);

     if( have_shaders ) {

         glsl_set_shader(DEFAULT_PROGRAM);

         glsl_set_uniform_int(DEFAULT_PROGRAM, "primary_texture", 0);

         glsl_set_uniform_int(DEFAULT_PROGRAM, "palette_texture", 1);

         glsl_clear_shader();

     }

 }

 /**

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

  * depth, culling

  */

 static void render_set_base_context( uint32_t poly1, gboolean set_depth )

 {

     if( set_depth ) {

         glDepthFunc( POLY1_DEPTH_MODE(poly1) );

     }

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

 }

 /**

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

  */

 static void render_set_tsp_context( uint32_t poly1, uint32_t poly2 )

 {

     glShadeModel( POLY1_SHADE_MODEL(poly1) );

     if( POLY1_TEXTURED(poly1) && !have_shaders ) {

         if( POLY2_TEX_BLEND(poly2) == 2 )

             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL );

         else

             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );

      }

      switch( POLY2_FOG_MODE(poly2) ) {

      case PVR2_POLY_FOG_LOOKUP:

          glFogfv( GL_FOG_COLOR, pvr2_scene.fog_lut_colour );

          break;

      case PVR2_POLY_FOG_VERTEX:

          glFogfv( GL_FOG_COLOR, pvr2_scene.fog_vert_colour );

          break;

      }

      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 depth_mode force depth mode, or 0 to use the polygon's

  * depth mode.

  */

 static void render_set_context( uint32_t *context, gboolean set_depth )

 {

     render_set_base_context(context[0], set_depth);

     render_set_tsp_context(context[0],context[1]);

 }

 static inline void gl_draw_vertexes( struct polygon_struct *poly )

 {

     do {

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

         poly = poly->sub_next;

     } while( poly != NULL );

 }

 static inline void gl_draw_mod_vertexes( struct polygon_struct *poly )

 {

     do {

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

         poly = poly->sub_next;

     } while( poly != NULL );

 }

 static void gl_render_poly( struct polygon_struct *poly, gboolean set_depth)

 {

     if( poly->vertex_count == 0 )

         return; /* Culled */

     bind_texture(poly->tex_id);

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

         render_set_context( poly->context, set_depth );

         gl_draw_vertexes(poly);

     }  else {

         glEnable( GL_STENCIL_TEST );

         render_set_base_context( poly->context[0], set_depth );

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

         glStencilFunc(GL_EQUAL, 0, 2);

         gl_draw_vertexes(poly);

         if( pvr2_scene.shadow_mode == SHADOW_FULL ) {

             bind_texture(poly->mod_tex_id);

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

         }

         glStencilFunc(GL_EQUAL, 2, 2);

         gl_draw_mod_vertexes(poly);

         glDisable( GL_STENCIL_TEST );

     }

 }

 static 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 :)

      */

     if( poly->vertex_count == 0 )

         return; /* Culled */

     gl_draw_vertexes(poly);

     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_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_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 );         

     }

 }

 static void gl_render_bkgnd( struct polygon_struct *poly )

 {

     bind_texture(poly->tex_id);

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

     glDisable( GL_DEPTH_TEST );

     glBlendFunc( GL_ONE, GL_ZERO );

     gl_draw_vertexes(poly);

     glEnable( GL_DEPTH_TEST );

 }

 void gl_render_triangle( struct polygon_struct *poly, int index )

 {

     bind_texture(poly->tex_id);

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

     glDrawArrays(GL_TRIANGLE_STRIP, poly->vertex_index + index, 3 );

 }

 void gl_render_tilelist( pvraddr_t tile_entry, gboolean set_depth )

 {

     tileentryiter list;

     FOREACH_TILEENTRY(list, tile_entry) {

         struct polygon_struct *poly = pvr2_scene.buf_to_poly_map[TILEENTRYITER_POLYADDR(list)];

         if( poly != NULL ) {

             do {

                 gl_render_poly(poly, set_depth);

                 poly = poly->next;

             } while( list.strip_count-- > 0 );

         }

     }

 }

 /**

  * Render the tilelist with depthbuffer updates only.

  */

 static void gl_render_tilelist_depthonly( pvraddr_t tile_entry )

 {

     tileentryiter list;

     FOREACH_TILEENTRY(list, tile_entry) {

         struct polygon_struct *poly = pvr2_scene.buf_to_poly_map[TILEENTRYITER_POLYADDR(list)];

         if( poly != NULL ) {

             do {

                 render_set_base_context(poly->context[0],TRUE);

                 gl_draw_vertexes(poly);

                 poly = poly->next;

             } while( list.strip_count-- > 0 );

         }

     }

 }

 static void gl_render_modifier_tilelist( pvraddr_t tile_entry, uint32_t tile_bounds[] )

 {

     tileentryiter list;

     if( !IS_TILE_PTR(tile_entry) )

         return;

     glEnable( GL_STENCIL_TEST );

     glEnable( GL_DEPTH_TEST );

     glStencilFunc( GL_ALWAYS, 0, 1 );

     glStencilOp( GL_KEEP,GL_INVERT, GL_KEEP ); 

     glStencilMask( 0x01 );

     glDepthFunc( GL_LEQUAL );

     glDepthMask( GL_FALSE );

     FOREACH_TILEENTRY(list, tile_entry ) {

         struct polygon_struct *poly = pvr2_scene.buf_to_poly_map[TILEENTRYITER_POLYADDR(list)];

         if( poly != NULL ) {

             do {

                 gl_render_modifier_polygon( poly, tile_bounds );

                 poly = poly->next;

             } while( list.strip_count-- > 0 );

         }

     }

     glDepthMask( GL_TRUE );

     glStencilOp( GL_KEEP, GL_KEEP, GL_KEEP );

     glDisable( GL_STENCIL_TEST );

 }

 /**

  * 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();

     currentTexId = -1;

     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(4, 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] );

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

     glsl_set_shader(DEFAULT_PROGRAM);

     /* Render the background */

     gl_render_bkgnd( pvr2_scene.bkgnd_poly );

     glEnable( GL_SCISSOR_TEST );

     glEnable( GL_COLOR_SUM );

     glEnable( GL_FOG );

     glEnable( GL_TEXTURE_2D );

     /* 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,TRUE);

         if( IS_TILE_PTR(segment->punchout_ptr) ) {

             glEnable(GL_ALPHA_TEST );

             glDepthFunc(GL_GEQUAL);

             gl_render_tilelist(segment->punchout_ptr, FALSE );

             glDisable(GL_ALPHA_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, TRUE);

             } else {

                 render_autosort_tile(segment->trans_ptr, RENDER_NORMAL );

             }

         }

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

     glDisable( GL_SCISSOR_TEST );

     glDisable( GL_COLOR_SUM );

     glDisable( GL_FOG );

     glsl_clear_shader();

     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 );

 }