material: route fogging state through CoglMaterial

Previously cogl_set_fog would cause a flush of the Cogl journal and
would directly bang the GL state machine to setup fogging. As part of
the ongoing effort to track most state in CoglMaterial to support
renderlists this now adds an indirection so that cogl_set_fog now just
updates ctx->legacy_fog_state. The fogging state then gets enabled as a
legacy override similar to how the old depth testing API is handled.

cogl/cogl-context.c

@@ -84,7 +84,6 @@ cogl_create_context (void)
   _cogl_material_init_default_layers ();
 
   _context->enable_flags = 0;
-  _context->fog_enabled = FALSE;
 
   _context->enable_backface_culling = FALSE;
   _context->flushed_front_winding = COGL_FRONT_WINDING_COUNTER_CLOCKWISE;
@@ -105,6 +104,8 @@ cogl_create_context (void)
   _context->active_texture_unit = 1;
   GE (glActiveTexture (GL_TEXTURE1));
 
+  _context->legacy_fog_state.enabled = FALSE;
+
   _context->simple_material = cogl_material_new ();
   _context->source_material = NULL;
   _context->arbfp_source_buffer = g_string_new ("");

cogl/cogl-context.h

@@ -56,7 +56,6 @@ typedef struct
 
   /* Enable cache */
   unsigned long     enable_flags;
-  gboolean          fog_enabled;
 
   gboolean          enable_backface_culling;
   CoglFrontWinding  flushed_front_winding;
@@ -73,6 +72,8 @@ typedef struct
   GArray           *texture_units;
   int               active_texture_unit;
 
+  CoglMaterialFogState legacy_fog_state;
+
   /* Materials */
   CoglMaterial     *simple_material;
   CoglMaterial     *source_material;

cogl/cogl-material-arbfp.c

@@ -250,7 +250,7 @@ _cogl_material_backend_arbfp_start (CoglMaterial *material,
     return FALSE;
 
   /* TODO: support fog */
-  if (ctx->fog_enabled)
+  if (ctx->legacy_fog_state.enabled)
     return FALSE;
 
   /* Note: we allocate ARBfp private state for both the given material

cogl/cogl-material-fixed.c

@@ -186,6 +186,54 @@ static gboolean
 _cogl_material_backend_fixed_end (CoglMaterial *material,
                                   unsigned long materials_difference)
 {
+  if (materials_difference & COGL_MATERIAL_STATE_FOG)
+    {
+      CoglMaterial *authority =
+        _cogl_material_get_authority (material, COGL_MATERIAL_STATE_FOG);
+      CoglMaterialFogState *fog_state = &authority->big_state->fog_state;
+
+      if (fog_state->enabled)
+        {
+          GLfloat fogColor[4];
+          GLenum gl_mode = GL_LINEAR;
+
+          fogColor[0] = cogl_color_get_red_float (&fog_state->color);
+          fogColor[1] = cogl_color_get_green_float (&fog_state->color);
+          fogColor[2] = cogl_color_get_blue_float (&fog_state->color);
+          fogColor[3] = cogl_color_get_alpha_float (&fog_state->color);
+
+          GE (glEnable (GL_FOG));
+
+          GE (glFogfv (GL_FOG_COLOR, fogColor));
+
+#if HAVE_COGL_GLES
+          switch (fog_state->mode)
+            {
+            case COGL_FOG_MODE_LINEAR:
+              gl_mode = GL_LINEAR;
+              break;
+            case COGL_FOG_MODE_EXPONENTIAL:
+              gl_mode = GL_EXP;
+              break;
+            case COGL_FOG_MODE_EXPONENTIAL_SQUARED:
+              gl_mode = GL_EXP2;
+              break;
+            }
+#endif
+          /* TODO: support other modes for GLES2 */
+
+          /* NB: GLES doesn't have glFogi */
+          GE (glFogf (GL_FOG_MODE, gl_mode));
+          GE (glHint (GL_FOG_HINT, GL_NICEST));
+
+          GE (glFogf (GL_FOG_DENSITY, fog_state->density));
+          GE (glFogf (GL_FOG_START, fog_state->z_near));
+          GE (glFogf (GL_FOG_END, fog_state->z_far));
+        }
+      else
+        GE (glDisable (GL_FOG));
+    }
+
   return TRUE;
 }
 

cogl/cogl-material-private.h

@@ -332,8 +332,9 @@ typedef enum _CoglMaterialState
   COGL_MATERIAL_STATE_BLEND             = 1L<<5,
   COGL_MATERIAL_STATE_USER_SHADER       = 1L<<6,
   COGL_MATERIAL_STATE_DEPTH             = 1L<<7,
+  COGL_MATERIAL_STATE_FOG               = 1L<<8,
 
-  COGL_MATERIAL_STATE_REAL_BLEND_ENABLE = 1L<<8,
+  COGL_MATERIAL_STATE_REAL_BLEND_ENABLE = 1L<<9,
 
   COGL_MATERIAL_STATE_ALL_SPARSE =
     COGL_MATERIAL_STATE_COLOR |
@@ -343,7 +344,8 @@ typedef enum _CoglMaterialState
     COGL_MATERIAL_STATE_ALPHA_FUNC |
     COGL_MATERIAL_STATE_BLEND |
     COGL_MATERIAL_STATE_USER_SHADER |
-    COGL_MATERIAL_STATE_DEPTH,
+    COGL_MATERIAL_STATE_DEPTH |
+    COGL_MATERIAL_STATE_FOG,
 
   COGL_MATERIAL_STATE_AFFECTS_BLENDING =
     COGL_MATERIAL_STATE_COLOR |
@@ -358,7 +360,8 @@ typedef enum _CoglMaterialState
     COGL_MATERIAL_STATE_ALPHA_FUNC |
     COGL_MATERIAL_STATE_BLEND |
     COGL_MATERIAL_STATE_USER_SHADER |
-    COGL_MATERIAL_STATE_DEPTH
+    COGL_MATERIAL_STATE_DEPTH |
+    COGL_MATERIAL_STATE_FOG
 
 } CoglMaterialState;
 
@@ -420,6 +423,16 @@ typedef struct
   float                 depth_range_far;
 } CoglMaterialDepthState;
 
+typedef struct
+{
+  gboolean        enabled;
+  CoglColor       color;
+  CoglFogMode     mode;
+  float           density;
+  float           z_near;
+  float           z_far;
+} CoglMaterialFogState;
+
 typedef struct
 {
   CoglMaterialLightingState lighting_state;
@@ -427,6 +440,7 @@ typedef struct
   CoglMaterialBlendState blend_state;
   CoglHandle user_program;
   CoglMaterialDepthState depth_state;
+  CoglMaterialFogState fog_state;
 } CoglMaterialBigState;
 
 typedef enum

cogl/cogl-material.c

@@ -2934,6 +2934,24 @@ _cogl_material_depth_state_equal (CoglMaterial *authority0,
                    sizeof (CoglMaterialDepthState)) == 0;
 }
 
+static gboolean
+_cogl_material_fog_state_equal (CoglMaterial *authority0,
+                                CoglMaterial *authority1)
+{
+  CoglMaterialFogState *fog_state0 = &authority0->big_state->fog_state;
+  CoglMaterialFogState *fog_state1 = &authority1->big_state->fog_state;
+
+  if (fog_state0->enabled == fog_state1->enabled &&
+      cogl_color_equal (&fog_state0->color, &fog_state1->color) &&
+      fog_state0->mode == fog_state1->mode &&
+      fog_state0->density == fog_state1->density &&
+      fog_state0->z_near == fog_state1->z_near &&
+      fog_state0->z_far == fog_state1->z_far)
+    return TRUE;
+  else
+    return FALSE;
+}
+
 static gboolean
 _cogl_material_layers_equal (CoglMaterial *authority0,
                              CoglMaterial *authority1)
@@ -3151,6 +3169,12 @@ _cogl_material_equal (CoglMaterial *material0,
                               _cogl_material_depth_state_equal))
     return FALSE;
 
+  if (!simple_property_equal (material0, material1,
+                              materials_difference,
+                              COGL_MATERIAL_STATE_FOG,
+                              _cogl_material_fog_state_equal))
+    return FALSE;
+
   if (!simple_property_equal (material0, material1,
                               materials_difference,
                               COGL_MATERIAL_STATE_LAYERS,
@@ -4097,6 +4121,41 @@ cogl_material_get_depth_range (CoglMaterial *material,
   *far_val = authority->big_state->depth_state.depth_range_far;
 }
 
+static void
+_cogl_material_set_fog_state (CoglMaterial *material,
+                              const CoglMaterialFogState *fog_state)
+{
+  CoglMaterialState state = COGL_MATERIAL_STATE_FOG;
+  CoglMaterial *authority;
+  CoglMaterialFogState *current_fog_state;
+
+  g_return_if_fail (cogl_is_material (material));
+
+  authority = _cogl_material_get_authority (material, state);
+
+  current_fog_state = &authority->big_state->fog_state;
+
+  if (current_fog_state->enabled == fog_state->enabled &&
+      cogl_color_equal (&current_fog_state->color, &fog_state->color) &&
+      current_fog_state->mode == fog_state->mode &&
+      current_fog_state->density == fog_state->density &&
+      current_fog_state->z_near == fog_state->z_near &&
+      current_fog_state->z_far == fog_state->z_far)
+    return;
+
+  /* - Flush journal primitives referencing the current state.
+   * - Make sure the material has no dependants so it may be modified.
+   * - If the material isn't currently an authority for the state being
+   *   changed, then initialize that state from the current authority.
+   */
+  _cogl_material_pre_change_notify (material, state, NULL);
+
+  material->big_state->fog_state = *fog_state;
+
+  _cogl_material_update_authority (material, authority, state,
+                                   _cogl_material_fog_state_equal);
+}
+
 unsigned long
 _cogl_material_get_age (CoglMaterial *material)
 {
@@ -5895,6 +5954,9 @@ _cogl_material_apply_legacy_state (CoglMaterial *material)
 
   if (ctx->legacy_depth_test_enabled)
     cogl_material_set_depth_test_enabled (material, TRUE);
+
+  if (ctx->legacy_fog_state.enabled)
+    _cogl_material_set_fog_state (material, &ctx->legacy_fog_state);
 }
 
 void

cogl/cogl.c

@@ -576,48 +576,17 @@ cogl_set_fog (const CoglColor *fog_color,
               float            z_near,
               float            z_far)
 {
-  GLfloat fogColor[4];
-  GLenum gl_mode = GL_LINEAR;
-
   _COGL_GET_CONTEXT (ctx, NO_RETVAL);
 
-  /* The cogl journal doesn't currently track fog state changes */
+  if (ctx->legacy_fog_state.enabled == FALSE)
-  _cogl_journal_flush ();
+    ctx->legacy_state_set++;
 
-  fogColor[0] = cogl_color_get_red_float (fog_color);
+  ctx->legacy_fog_state.enabled = TRUE;
-  fogColor[1] = cogl_color_get_green_float (fog_color);
+  ctx->legacy_fog_state.color = *fog_color;
-  fogColor[2] = cogl_color_get_blue_float (fog_color);
+  ctx->legacy_fog_state.mode = mode;
-  fogColor[3] = cogl_color_get_alpha_float (fog_color);
+  ctx->legacy_fog_state.density = density;
-
+  ctx->legacy_fog_state.z_near = z_near;
-  glEnable (GL_FOG);
+  ctx->legacy_fog_state.z_far = z_far;
-
-  glFogfv (GL_FOG_COLOR, fogColor);
-
-#if HAVE_COGL_GLES
-  switch (mode)
-    {
-    case COGL_FOG_MODE_LINEAR:
-      gl_mode = GL_LINEAR;
-      break;
-    case COGL_FOG_MODE_EXPONENTIAL:
-      gl_mode = GL_EXP;
-      break;
-    case COGL_FOG_MODE_EXPONENTIAL_SQUARED:
-      gl_mode = GL_EXP2;
-      break;
-    }
-#endif
-  /* TODO: support other modes for GLES2 */
-
-  /* NB: GLES doesn't have glFogi */
-  glFogf (GL_FOG_MODE, gl_mode);
-  glHint (GL_FOG_HINT, GL_NICEST);
-
-  glFogf (GL_FOG_DENSITY, (GLfloat) density);
-  glFogf (GL_FOG_START, (GLfloat) z_near);
-  glFogf (GL_FOG_END, (GLfloat) z_far);
-
-  ctx->fog_enabled = TRUE;
 }
 
 void
@@ -625,11 +594,10 @@ cogl_disable_fog (void)
 {
   _COGL_GET_CONTEXT (ctx, NO_RETVAL);
 
-  /* Currently the journal can't track changes to fog state... */
+  if (ctx->legacy_fog_state.enabled == TRUE)
-  _cogl_journal_flush ();
+    ctx->legacy_state_set--;
 
-  glDisable (GL_FOG);
+  ctx->legacy_fog_state.enabled = FALSE;
-  ctx->fog_enabled = FALSE;
 }
 
 void