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gsk: Add redirection to FBOs for opacity groups

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If a node is non-opaque and has a non-zero opacity we need to paint its
contents and children first to an off screen buffer, and then render the
resulting texture at the desired opacity — otherwise the opacities will
combine and result in the wrong rendering.
This commit is contained in:
Emmanuele Bassi 2016-07-25 17:15:05 +01:00
parent 8ac9127283
commit 9e22118feb
1 changed files with 129 additions and 32 deletions
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161
gsk/gskglrenderer.c
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@ -56,6 +56,8 @@ typedef struct {
RenderData render_data;
RenderData *parent_data;
GArray *children;
} RenderItem;
enum {
@ -356,6 +358,18 @@ render_item (GskGLRenderer *self,
RenderItem *item)
{
float mvp[16];
float opacity;
if (item->children != NULL)
{
if (gsk_gl_driver_bind_render_target (self->gl_driver, item->render_data.render_target_id))
{
glViewport (0, 0, item->size.width, item->size.height);
glClearColor (0.0, 0.0, 0.0, 0.0);
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
}
}
gsk_gl_driver_bind_vao (self->gl_driver, item->render_data.vao_id);
@ -378,7 +392,12 @@ render_item (GskGLRenderer *self,
}
/* Pass the opacity component */
glUniform1f (item->render_data.alpha_location, item->opaque ? 1 : item->opacity);
if (item->children != NULL || item->opaque)
opacity = 1.0;
else
opacity = item->opacity;
glUniform1f (item->render_data.alpha_location, opacity);
/* Pass the mvp to the vertex shader */
GSK_NOTE (OPENGL, graphene_matrix_print (&item->mvp));
@ -392,6 +411,55 @@ render_item (GskGLRenderer *self,
item->opaque ? 1 : item->opacity));
glDrawArrays (GL_TRIANGLES, 0, N_VERTICES);
/* Render all children items, so we can take the result
* render target texture during the compositing
*/
if (item->children != NULL)
{
int i;
for (i = 0; i < item->children->len; i++)
{
RenderItem *child = &g_array_index (item->children, RenderItem, i);
render_item (self, child);
}
/* Bind the parent render target */
if (item->parent_data != NULL)
gsk_gl_driver_bind_render_target (self->gl_driver, item->parent_data->render_target_id);
/* Bind the same VAO, as the render target is created with the same size
* and vertices as the texture target
*/
gsk_gl_driver_bind_vao (self->gl_driver, item->render_data.vao_id);
/* Since we're rendering the target texture, we only need the blit program */
glUseProgram (self->blit_program_id);
/* Use texture unit 0 for the render target */
glUniform1i (item->render_data.source_location, 0);
gsk_gl_driver_bind_source_texture (self->gl_driver, item->render_data.render_target_id);
/* Pass the opacity component; if we got here, we know that the original render
* target is neither fully opaque nor at full opacity
*/
glUniform1f (item->render_data.alpha_location, item->opacity);
/* Pass the mvp to the vertex shader */
GSK_NOTE (OPENGL, graphene_matrix_print (&item->mvp));
graphene_matrix_to_float (&item->mvp, mvp);
glUniformMatrix4fv (item->render_data.mvp_location, 1, GL_FALSE, mvp);
/* Draw the quad */
GSK_NOTE (OPENGL, g_print ("Drawing offscreen item <%s>[%p] with opacity: %g\n",
item->name,
item,
item->opacity));
glDrawArrays (GL_TRIANGLES, 0, N_VERTICES);
}
}
static void
@ -460,8 +528,23 @@ project_item (const graphene_matrix_t *projection,
return graphene_vec4_get_z (&vec) / graphene_vec4_get_w (&vec);
}
static gboolean
render_node_needs_render_target (GskRenderNode *node)
{
if (!gsk_render_node_is_opaque (node))
{
double opacity = gsk_render_node_get_opacity (node);
if (opacity < 1.0)
return TRUE;
}
return FALSE;
}
static void
gsk_gl_renderer_add_render_item (GskGLRenderer *self,
GArray *render_items,
GskRenderNode *node,
RenderItem *parent)
{
@ -521,11 +604,22 @@ gsk_gl_renderer_add_render_item (GskGLRenderer *self,
else
item.parent_data = NULL;
/* Select the render target */
if (parent != NULL)
item.render_data.render_target_id = parent->render_data.render_target_id;
/* Select the render target; -1 is the default */
if (render_node_needs_render_target (node))
{
item.render_data.render_target_id =
gsk_gl_driver_create_texture (self->gl_driver, bounds.size.width, bounds.size.height);
gsk_gl_driver_init_texture_empty (self->gl_driver, item.render_data.render_target_id);
gsk_gl_driver_create_render_target (self->gl_driver, item.render_data.render_target_id, TRUE, TRUE);
item.children = g_array_sized_new (FALSE, FALSE, sizeof (RenderItem),
gsk_render_node_get_n_children (node));
}
else
item.render_data.render_target_id = self->texture_id;
{
item.render_data.render_target_id = self->texture_id;
item.children = NULL;
}
/* Select the program to use */
if (parent != NULL)
@ -583,38 +677,34 @@ gsk_gl_renderer_add_render_item (GskGLRenderer *self,
*/
surface = gsk_render_node_get_surface (node);
/* If the node does not have any surface we skip drawing it, but we still
* recurse.
*
* XXX: This needs to be re-done if the opacity is != 0, in which case we
* need to composite the opacity level of the children
*/
if (surface == NULL)
goto recurse_children;
/* Upload the Cairo surface to a GL texture */
item.render_data.texture_id = gsk_gl_driver_create_texture (self->gl_driver,
bounds.size.width,
bounds.size.height);
gsk_gl_driver_bind_source_texture (self->gl_driver, item.render_data.texture_id);
gsk_gl_driver_init_texture_with_surface (self->gl_driver,
item.render_data.texture_id,
surface,
self->gl_min_filter,
self->gl_mag_filter);
if (surface != NULL)
{
/* Upload the Cairo surface to a GL texture */
item.render_data.texture_id = gsk_gl_driver_create_texture (self->gl_driver,
bounds.size.width,
bounds.size.height);
gsk_gl_driver_bind_source_texture (self->gl_driver, item.render_data.texture_id);
gsk_gl_driver_init_texture_with_surface (self->gl_driver,
item.render_data.texture_id,
surface,
self->gl_min_filter,
self->gl_mag_filter);
}
GSK_NOTE (OPENGL, g_print ("Adding node <%s>[%p] to render items\n",
node->name != NULL ? node->name : "unnamed",
node));
g_array_append_val (self->render_items, item);
ritem = &g_array_index (self->render_items,
g_array_append_val (render_items, item);
ritem = &g_array_index (render_items,
RenderItem,
self->render_items->len - 1);
render_items->len - 1);
if (item.children != NULL)
render_items = item.children;
recurse_children:
gsk_render_node_iter_init (&iter, node);
while (gsk_render_node_iter_next (&iter, &child))
gsk_gl_renderer_add_render_item (self, child, ritem);
gsk_gl_renderer_add_render_item (self, render_items, child, ritem);
}
static gboolean
@ -638,7 +728,7 @@ gsk_gl_renderer_validate_tree (GskGLRenderer *self,
gsk_gl_driver_begin_frame (self->gl_driver);
GSK_NOTE (OPENGL, g_print ("RenderNode -> RenderItem\n"));
gsk_gl_renderer_add_render_item (self, root, NULL);
gsk_gl_renderer_add_render_item (self, self->render_items, root, NULL);
GSK_NOTE (OPENGL, g_print ("Total render items: %d of max:%d\n",
self->render_items->len,
@ -649,6 +739,14 @@ gsk_gl_renderer_validate_tree (GskGLRenderer *self,
return TRUE;
}
static void
render_item_clear (RenderItem *item,
GskGLRenderer *self)
{
gsk_gl_driver_destroy_texture (self->gl_driver, item->render_data.texture_id);
gsk_gl_driver_destroy_vao (self->gl_driver, item->render_data.vao_id);
}
static void
gsk_gl_renderer_clear_tree (GskGLRenderer *self)
{
@ -663,8 +761,7 @@ gsk_gl_renderer_clear_tree (GskGLRenderer *self)
{
RenderItem *item = &g_array_index (self->render_items, RenderItem, i);
gsk_gl_driver_destroy_texture (self->gl_driver, item->render_data.texture_id);
gsk_gl_driver_destroy_vao (self->gl_driver, item->render_data.vao_id);
render_item_clear (item, self);
}
g_clear_pointer (&self->render_items, g_array_unref);