/**

  * $Id$

  *

  * 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, GLint depth_mode )

 {

     if( depth_mode == 0 ) {

         glDepthFunc( POLY1_DEPTH_MODE(poly1) );

     } else {

         glDepthFunc(depth_mode);

     }

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

     render_set_cull( poly1 );

 }

 /**

  * 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 )

 {

     glShadeModel( POLY1_SHADE_MODEL(poly1) );

     if( POLY1_SPECULAR(poly1) ) {

         glEnable(GL_COLOR_SUM);

     } else {

         glDisable(GL_COLOR_SUM);

     }

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

  * depth mode.

  */

 void render_set_context( uint32_t *context, GLint depth_mode )

 {

     render_set_base_context(context[0], depth_mode);

     render_set_tsp_context(context[0],context[1],context[2]);

 }

 static void gl_render_poly( struct polygon_struct *poly, GLint depth_mode )

 {

     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, depth_mode );

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

     }  else {

         glEnable( GL_STENCIL_TEST );

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

         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, 0 );

     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, GLint depth_mode )

 {

     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, depth_mode );

                 poly = poly->next;

                 strip_count--;

             }

             break;

         default:

             if( entry & 0x7E000000 ) {

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

                 gl_render_poly( poly, depth_mode );

             }

         }

     }       

 }

 /**

  * 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],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],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,0);

         if( IS_TILE_PTR(segment->punchout_ptr) ) {

             glEnable(GL_ALPHA_TEST );

             gl_render_tilelist(segment->punchout_ptr, GL_GEQUAL );

             glDisable(GL_ALPHA_TEST );

         }

         glDisable( GL_STENCIL_TEST );

         glStencilMask(0x03);

         glClear( GL_STENCIL_BUFFER_BIT );

         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, 0);

             } 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 );

 }