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cogl/clip-stack: Restore old matrices after drawing to stencil buffer

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When using a region clip and something has a rectangle clip pushed, a
special drawing method for ClutterTexts (emit_vertex_buffer_geometry()
in cogl-pango-display-list.c) starts to fail and clipping issues with
long texts (because emit_vertex_buffer_geometry() is only used for texts
longer than 25 characters) start to appear. This specifically happened
in Looking Glass, where the StViewport of the ScrollView sets a
rectangle clips and the texts are usually longer than 25 characters.

This is caused by the changing of the perspective and modelview matrix
when drawing to the stencil buffer and started happening when
region-clipping was introduced with commit 8598b654. Even though the
changing of the matrices was done before that, too, the issue probably
didn't happen because `rect->can_be_scissor` was TRUE and no stencil
buffer clipping was used at all.

To fix this, temporarily save the old matrices, then set the new ones
and restore the old ones when we're done drawing to the stencil buffer.

Fixes https://gitlab.gnome.org/GNOME/gnome-shell/issues/2246

https://gitlab.gnome.org/GNOME/mutter/merge_requests/1096
This commit is contained in:
Jonas Dreßler 2020-02-26 16:30:29 +01:00 committed by Carlos Garnacho
parent d30ef0dd3b
commit 72054332c5
1 changed files with 29 additions and 12 deletions
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41
cogl/cogl/driver/gl/cogl-clip-stack-gl.c
View File

@ -62,14 +62,16 @@ add_stencil_clip_rectangle (CoglFramebuffer *framebuffer,
CoglMatrixStack *projection_stack =
_cogl_framebuffer_get_projection_stack (framebuffer);
CoglContext *ctx = cogl_framebuffer_get_context (framebuffer);
CoglMatrixEntry *old_projection_entry, *old_modelview_entry;
/* NB: This can be called while flushing the journal so we need
* to be very conservative with what state we change.
*/
old_projection_entry = g_steal_pointer (&ctx->current_projection_entry);
old_modelview_entry = g_steal_pointer (&ctx->current_modelview_entry);
_cogl_context_set_current_projection_entry (ctx,
projection_stack->last_entry);
_cogl_context_set_current_modelview_entry (ctx, modelview_entry);
ctx->current_projection_entry = projection_stack->last_entry;
ctx->current_modelview_entry = modelview_entry;
if (merge)
{
@ -86,8 +88,8 @@ add_stencil_clip_rectangle (CoglFramebuffer *framebuffer,
rectangle are set will be valid */
GE( ctx, glStencilOp (GL_DECR, GL_DECR, GL_DECR) );
_cogl_context_set_current_projection_entry (ctx, &ctx->identity_entry);
_cogl_context_set_current_modelview_entry (ctx, &ctx->identity_entry);
ctx->current_projection_entry = &ctx->identity_entry;
ctx->current_modelview_entry = &ctx->identity_entry;
_cogl_rectangle_immediate (framebuffer,
ctx->stencil_pipeline,
@ -109,6 +111,9 @@ add_stencil_clip_rectangle (CoglFramebuffer *framebuffer,
x_1, y_1, x_2, y_2);
}
ctx->current_projection_entry = old_projection_entry;
ctx->current_modelview_entry = old_modelview_entry;
/* Restore the stencil mode */
GE( ctx, glStencilFunc (GL_EQUAL, 0x1, 0x1) );
GE( ctx, glStencilOp (GL_KEEP, GL_KEEP, GL_KEEP) );
@ -120,6 +125,7 @@ add_stencil_clip_region (CoglFramebuffer *framebuffer,
gboolean merge)
{
CoglContext *ctx = cogl_framebuffer_get_context (framebuffer);
CoglMatrixEntry *old_projection_entry, *old_modelview_entry;
CoglMatrix matrix;
int num_rectangles = cairo_region_num_rectangles (region);
int i;
@ -128,8 +134,11 @@ add_stencil_clip_region (CoglFramebuffer *framebuffer,
/* NB: This can be called while flushing the journal so we need
* to be very conservative with what state we change.
*/
_cogl_context_set_current_projection_entry (ctx, &ctx->identity_entry);
_cogl_context_set_current_modelview_entry (ctx, &ctx->identity_entry);
old_projection_entry = g_steal_pointer (&ctx->current_projection_entry);
old_modelview_entry = g_steal_pointer (&ctx->current_modelview_entry);
ctx->current_projection_entry = &ctx->identity_entry;
ctx->current_modelview_entry = &ctx->identity_entry;
/* The coordinates in the region are meant to be window coordinates,
* make a matrix that translates those across the viewport, and into
@ -223,6 +232,9 @@ add_stencil_clip_region (CoglFramebuffer *framebuffer,
-1.0, -1.0, 1.0, 1.0);
}
ctx->current_projection_entry = old_projection_entry;
ctx->current_modelview_entry = old_modelview_entry;
/* Restore the stencil mode */
GE (ctx, glDepthMask (TRUE));
GE (ctx, glColorMask (TRUE, TRUE, TRUE, TRUE));
@ -249,14 +261,16 @@ add_stencil_clip_silhouette (CoglFramebuffer *framebuffer,
CoglMatrixStack *projection_stack =
_cogl_framebuffer_get_projection_stack (framebuffer);
CoglContext *ctx = cogl_framebuffer_get_context (framebuffer);
CoglMatrixEntry *old_projection_entry, *old_modelview_entry;
/* NB: This can be called while flushing the journal so we need
* to be very conservative with what state we change.
*/
old_projection_entry = g_steal_pointer (&ctx->current_projection_entry);
old_modelview_entry = g_steal_pointer (&ctx->current_modelview_entry);
_cogl_context_set_current_projection_entry (ctx,
projection_stack->last_entry);
_cogl_context_set_current_modelview_entry (ctx, modelview_entry);
ctx->current_projection_entry = projection_stack->last_entry;
ctx->current_modelview_entry = modelview_entry;
_cogl_pipeline_flush_gl_state (ctx, ctx->stencil_pipeline,
framebuffer, FALSE, FALSE);
@ -314,8 +328,8 @@ add_stencil_clip_silhouette (CoglFramebuffer *framebuffer,
/* Decrement all of the bits twice so that only pixels where the
value is 3 will remain */
_cogl_context_set_current_projection_entry (ctx, &ctx->identity_entry);
_cogl_context_set_current_modelview_entry (ctx, &ctx->identity_entry);
ctx->current_projection_entry = &ctx->identity_entry;
ctx->current_modelview_entry = &ctx->identity_entry;
_cogl_rectangle_immediate (framebuffer, ctx->stencil_pipeline,
-1.0, -1.0, 1.0, 1.0);
@ -323,6 +337,9 @@ add_stencil_clip_silhouette (CoglFramebuffer *framebuffer,
-1.0, -1.0, 1.0, 1.0);
}
ctx->current_projection_entry = old_projection_entry;
ctx->current_modelview_entry = old_modelview_entry;
GE (ctx, glStencilMask (~(GLuint) 0));
GE (ctx, glDepthMask (TRUE));
GE (ctx, glColorMask (TRUE, TRUE, TRUE, TRUE));