From 702873c199ca4175a1aaa26fce1c79cb65f4a916 Mon Sep 17 00:00:00 2001 From: Neil Roberts Date: Thu, 17 May 2012 23:28:24 +0100 Subject: [PATCH] matrix-stack: Prune stack entries when loading a replacement matrix Previously if an application does not use the matrix stack as a stack but instead just loads its own matrices for each frame using cogl_framebuffer_set_modelview_matrix then it will continously push OP_LOAD entries on the stack and the stack will grow forever. This patch fixes that use case by resetting the top of the stack to the last save entry whenever something is pushed that replaces the previous matrix on the stack. Reviewed-by: Robert Bragg (cherry picked from commit d31ed33241a9e9e3bc25f01b2614678827a7a9aa) --- cogl/cogl-matrix-stack.c | 66 ++++++++++++++++++++++++++++++---------- 1 file changed, 50 insertions(+), 16 deletions(-) diff --git a/cogl/cogl-matrix-stack.c b/cogl/cogl-matrix-stack.c index 14a9040dc..2d61a5eae 100644 --- a/cogl/cogl-matrix-stack.c +++ b/cogl/cogl-matrix-stack.c @@ -69,6 +69,34 @@ _cogl_matrix_stack_push_entry (CoglMatrixStack *stack, return entry; } +static void * +_cogl_matrix_stack_push_replacement_entry (CoglMatrixStack *stack, + size_t size, + CoglMatrixOp operation) +{ + CoglMatrixEntry *old_top = stack->last_entry; + CoglMatrixEntry *new_top; + + /* This would only be called for operations that completely replace + * the matrix. In that case we don't need to keep a reference to + * anything up to the last save entry. This optimisation could be + * important for applications that aren't using the stack but + * instead just perform their own matrix manipulations and load a + * new stack every frame. If this optimisation isn't done then the + * stack would just grow endlessly. See the comments + * _cogl_matrix_stack_pop for a description of how popping works. */ + for (new_top = old_top; + new_top->op != COGL_MATRIX_OP_SAVE && new_top->parent; + new_top = new_top->parent) + ; + + _cogl_matrix_entry_ref (new_top); + _cogl_matrix_entry_unref (old_top); + stack->last_entry = new_top; + + return _cogl_matrix_stack_push_entry (stack, size, operation); +} + void _cogl_matrix_entry_identity_init (CoglMatrixEntry *entry) { @@ -81,9 +109,9 @@ _cogl_matrix_entry_identity_init (CoglMatrixEntry *entry) void _cogl_matrix_stack_load_identity (CoglMatrixStack *stack) { - _cogl_matrix_stack_push_entry (stack, - sizeof (CoglMatrixEntry), - COGL_MATRIX_OP_LOAD_IDENTITY); + _cogl_matrix_stack_push_replacement_entry (stack, + sizeof (CoglMatrixEntry), + COGL_MATRIX_OP_LOAD_IDENTITY); } void @@ -192,9 +220,10 @@ _cogl_matrix_stack_set (CoglMatrixStack *stack, { CoglMatrixEntryLoad *entry; - entry = _cogl_matrix_stack_push_entry (stack, - sizeof (CoglMatrixEntryLoad), - COGL_MATRIX_OP_LOAD); + entry = + _cogl_matrix_stack_push_replacement_entry (stack, + sizeof (CoglMatrixEntryLoad), + COGL_MATRIX_OP_LOAD); entry->matrix = _cogl_magazine_chunk_alloc (_cogl_matrix_stack_matrices_magazine); @@ -213,9 +242,10 @@ _cogl_matrix_stack_frustum (CoglMatrixStack *stack, { CoglMatrixEntryLoad *entry; - entry = _cogl_matrix_stack_push_entry (stack, - sizeof (CoglMatrixEntryLoad), - COGL_MATRIX_OP_LOAD); + entry = + _cogl_matrix_stack_push_replacement_entry (stack, + sizeof (CoglMatrixEntryLoad), + COGL_MATRIX_OP_LOAD); entry->matrix = _cogl_magazine_chunk_alloc (_cogl_matrix_stack_matrices_magazine); @@ -235,9 +265,10 @@ _cogl_matrix_stack_perspective (CoglMatrixStack *stack, { CoglMatrixEntryLoad *entry; - entry = _cogl_matrix_stack_push_entry (stack, - sizeof (CoglMatrixEntryLoad), - COGL_MATRIX_OP_LOAD); + entry = + _cogl_matrix_stack_push_replacement_entry (stack, + sizeof (CoglMatrixEntryLoad), + COGL_MATRIX_OP_LOAD); entry->matrix = _cogl_magazine_chunk_alloc (_cogl_matrix_stack_matrices_magazine); @@ -258,9 +289,10 @@ _cogl_matrix_stack_orthographic (CoglMatrixStack *stack, { CoglMatrixEntryLoad *entry; - entry = _cogl_matrix_stack_push_entry (stack, - sizeof (CoglMatrixEntryLoad), - COGL_MATRIX_OP_LOAD); + entry = + _cogl_matrix_stack_push_replacement_entry (stack, + sizeof (CoglMatrixEntryLoad), + COGL_MATRIX_OP_LOAD); entry->matrix = _cogl_magazine_chunk_alloc (_cogl_matrix_stack_matrices_magazine); @@ -605,7 +637,9 @@ _cogl_matrix_stack_new (void) stack->last_entry = NULL; - _cogl_matrix_stack_load_identity (stack); + _cogl_matrix_stack_push_entry (stack, + sizeof (CoglMatrixEntry), + COGL_MATRIX_OP_LOAD_IDENTITY); return _cogl_matrix_stack_object_new (stack); }