cairo_status_t
_cairo_gl_composite_begin_tristrip (cairo_gl_composite_t *setup,
cairo_gl_context_t **ctx_out)
{
cairo_gl_context_t *ctx;
cairo_status_t status;
cairo_gl_shader_t *shader;
int src_size, dst_size;
cairo_gl_operand_t default_mask;
memset (&default_mask, 0, sizeof (cairo_gl_operand_t));
assert (setup->dst);
status = _cairo_gl_context_acquire (setup->dst->base.device, &ctx);
if (unlikely (status))
return status;
*ctx_out = ctx;
/* Finish any pending operations from other GL compositors. */
if (! _cairo_gl_context_is_flushed (ctx))
_cairo_gl_composite_flush (ctx);
glEnable (GL_BLEND);
status = _cairo_gl_get_shader_by_type (ctx,
&setup->src,
&default_mask,
setup->spans,
CAIRO_GL_SHADER_IN_NORMAL,
&shader);
if (unlikely (status)) {
status = _cairo_gl_context_release (ctx, status);
return status;
}
_cairo_gl_context_set_destination (ctx, setup->dst);
_cairo_gl_set_operator (ctx, setup->op, FALSE);
_cairo_gl_set_shader (ctx, shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
dst_size = 2 * sizeof (GLfloat);
src_size = _cairo_gl_operand_get_vertex_size (setup->src.type);
ctx->vertex_size = dst_size + src_size;
ctx->dispatch.BindBuffer (GL_ARRAY_BUFFER, ctx->vbo);
ctx->dispatch.VertexAttribPointer (CAIRO_GL_VERTEX_ATTRIB_INDEX, 2,
GL_FLOAT, GL_FALSE, ctx->vertex_size, NULL);
ctx->dispatch.EnableVertexAttribArray (CAIRO_GL_VERTEX_ATTRIB_INDEX);
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_SOURCE, &setup->src,
ctx->vertex_size, dst_size);
return status;
}
cairo_status_t
_cairo_gl_composite_begin (cairo_gl_composite_t *setup,
cairo_gl_context_t **ctx_out)
{
unsigned int dst_size, src_size, mask_size, vertex_size;
cairo_gl_context_t *ctx;
cairo_status_t status;
cairo_bool_t component_alpha;
cairo_gl_shader_t *shader;
assert (setup->dst);
status = _cairo_gl_context_acquire (setup->dst->base.device, &ctx);
if (unlikely (status))
return status;
glEnable (GL_BLEND);
component_alpha =
setup->mask.type == CAIRO_GL_OPERAND_TEXTURE &&
setup->mask.texture.attributes.has_component_alpha;
/* Do various magic for component alpha */
if (component_alpha) {
status = _cairo_gl_composite_begin_component_alpha (ctx, setup);
if (unlikely (status))
goto FAIL;
} else {
if (ctx->pre_shader) {
_cairo_gl_composite_flush (ctx);
ctx->pre_shader = NULL;
}
}
status = _cairo_gl_get_shader_by_type (ctx,
&setup->src,
&setup->mask,
setup->spans,
component_alpha ?
CAIRO_GL_SHADER_IN_CA_SOURCE :
CAIRO_GL_SHADER_IN_NORMAL,
&shader);
if (unlikely (status)) {
ctx->pre_shader = NULL;
goto FAIL;
}
if (ctx->current_shader != shader)
_cairo_gl_composite_flush (ctx);
status = CAIRO_STATUS_SUCCESS;
dst_size = 2 * sizeof (GLfloat);
src_size = _cairo_gl_operand_get_vertex_size (setup->src.type);
mask_size = _cairo_gl_operand_get_vertex_size (setup->mask.type);
vertex_size = dst_size + src_size + mask_size;
if (setup->spans)
vertex_size += sizeof (GLfloat);
if (ctx->vertex_size != vertex_size)
_cairo_gl_composite_flush (ctx);
_cairo_gl_context_set_destination (ctx, setup->dst);
if (_cairo_gl_context_is_flushed (ctx)) {
ctx->dispatch.BindBuffer (GL_ARRAY_BUFFER, ctx->vbo);
ctx->dispatch.VertexAttribPointer (CAIRO_GL_VERTEX_ATTRIB_INDEX, 2,
GL_FLOAT, GL_FALSE, vertex_size, NULL);
ctx->dispatch.EnableVertexAttribArray (CAIRO_GL_VERTEX_ATTRIB_INDEX);
}
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_SOURCE, &setup->src, vertex_size, dst_size);
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_MASK, &setup->mask, vertex_size, dst_size + src_size);
if (setup->spans)
_cairo_gl_context_setup_spans (ctx, vertex_size, dst_size + src_size + mask_size);
else
ctx->dispatch.DisableVertexAttribArray (CAIRO_GL_COLOR_ATTRIB_INDEX);
_cairo_gl_set_operator (ctx, setup->op, component_alpha);
ctx->vertex_size = vertex_size;
if (_cairo_gl_context_is_flushed (ctx)) {
if (ctx->pre_shader) {
_cairo_gl_set_shader (ctx, ctx->pre_shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
}
_cairo_gl_set_shader (ctx, shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
}
if (! _cairo_gl_context_is_flushed (ctx) &&
! cairo_region_equal (ctx->clip_region, setup->clip_region))
_cairo_gl_composite_flush (ctx);
cairo_region_destroy (ctx->clip_region);
ctx->clip_region = cairo_region_reference (setup->clip_region);
if (ctx->clip_region)
glEnable (GL_SCISSOR_TEST);
else
glDisable (GL_SCISSOR_TEST);
*ctx_out = ctx;
FAIL:
if (unlikely (status))
status = _cairo_gl_context_release (ctx, status);
return status;
}
static cairo_status_t
_cairo_gl_composite_begin_component_alpha (cairo_gl_context_t *ctx,
cairo_gl_composite_t *setup)
{
cairo_gl_shader_t *pre_shader = NULL;
cairo_status_t status;
/* For CLEAR, cairo's rendering equation (quoting Owen's description in:
* http://lists.cairographics.org/archives/cairo/2005-August/004992.html)
* is:
* mask IN clip ? src OP dest : dest
* or more simply:
* mask IN CLIP ? 0 : dest
*
* where the ternary operator A ? B : C is (A * B) + ((1 - A) * C).
*
* The model we use in _cairo_gl_set_operator() is Render's:
* src IN mask IN clip OP dest
* which would boil down to:
* 0 (bounded by the extents of the drawing).
*
* However, we can do a Render operation using an opaque source
* and DEST_OUT to produce:
* 1 IN mask IN clip DEST_OUT dest
* which is
* mask IN clip ? 0 : dest
*/
if (setup->op == CAIRO_OPERATOR_CLEAR) {
_cairo_gl_solid_operand_init (&setup->src, CAIRO_COLOR_WHITE);
setup->op = CAIRO_OPERATOR_DEST_OUT;
}
/*
* implements component-alpha %CAIRO_OPERATOR_OVER using two passes of
* the simpler operations %CAIRO_OPERATOR_DEST_OUT and %CAIRO_OPERATOR_ADD.
*
* From http://anholt.livejournal.com/32058.html:
*
* The trouble is that component-alpha rendering requires two different sources
* for blending: one for the source value to the blender, which is the
* per-channel multiplication of source and mask, and one for the source alpha
* for multiplying with the destination channels, which is the multiplication
* of the source channels by the mask alpha. So the equation for Over is:
*
* dst.A = src.A * mask.A + (1 - (src.A * mask.A)) * dst.A
* dst.R = src.R * mask.R + (1 - (src.A * mask.R)) * dst.R
* dst.G = src.G * mask.G + (1 - (src.A * mask.G)) * dst.G
* dst.B = src.B * mask.B + (1 - (src.A * mask.B)) * dst.B
*
* But we can do some simpler operations, right? How about PictOpOutReverse,
* which has a source factor of 0 and dest factor of (1 - source alpha). We
* can get the source alpha value (srca.X = src.A * mask.X) out of the texture
* blenders pretty easily. So we can do a component-alpha OutReverse, which
* gets us:
*
* dst.A = 0 + (1 - (src.A * mask.A)) * dst.A
* dst.R = 0 + (1 - (src.A * mask.R)) * dst.R
* dst.G = 0 + (1 - (src.A * mask.G)) * dst.G
* dst.B = 0 + (1 - (src.A * mask.B)) * dst.B
*
* OK. And if an op doesn't use the source alpha value for the destination
* factor, then we can do the channel multiplication in the texture blenders
* to get the source value, and ignore the source alpha that we wouldn't use.
* We've supported this in the Radeon driver for a long time. An example would
* be PictOpAdd, which does:
*
* dst.A = src.A * mask.A + dst.A
* dst.R = src.R * mask.R + dst.R
* dst.G = src.G * mask.G + dst.G
* dst.B = src.B * mask.B + dst.B
*
* Hey, this looks good! If we do a PictOpOutReverse and then a PictOpAdd right
* after it, we get:
*
* dst.A = src.A * mask.A + ((1 - (src.A * mask.A)) * dst.A)
* dst.R = src.R * mask.R + ((1 - (src.A * mask.R)) * dst.R)
* dst.G = src.G * mask.G + ((1 - (src.A * mask.G)) * dst.G)
* dst.B = src.B * mask.B + ((1 - (src.A * mask.B)) * dst.B)
*
* This two-pass trickery could be avoided using a new GL extension that
* lets two values come out of the shader and into the blend unit.
*/
if (setup->op == CAIRO_OPERATOR_OVER) {
setup->op = CAIRO_OPERATOR_ADD;
status = _cairo_gl_get_shader_by_type (ctx,
&setup->src,
&setup->mask,
setup->spans,
CAIRO_GL_SHADER_IN_CA_SOURCE_ALPHA,
&pre_shader);
if (unlikely (status))
return status;
}
if (ctx->pre_shader != pre_shader)
_cairo_gl_composite_flush (ctx);
ctx->pre_shader = pre_shader;
return CAIRO_STATUS_SUCCESS;
}
cairo_status_t
_cairo_gl_composite_begin_multisample (cairo_gl_composite_t *setup,
cairo_gl_context_t **ctx_out,
cairo_bool_t multisampling)
{
unsigned int dst_size, src_size, mask_size, vertex_size;
cairo_gl_context_t *ctx;
cairo_status_t status;
cairo_bool_t component_alpha;
cairo_gl_shader_t *shader;
cairo_operator_t op = setup->op;
cairo_surface_t *mask_surface = NULL;
assert (setup->dst);
status = _cairo_gl_context_acquire (setup->dst->base.device, &ctx);
if (unlikely (status))
return status;
_cairo_gl_context_set_destination (ctx, setup->dst, multisampling);
if (ctx->states_cache.blend_enabled == FALSE) {
glEnable (GL_BLEND);
ctx->states_cache.blend_enabled = TRUE;
}
component_alpha =
setup->mask.type == CAIRO_GL_OPERAND_TEXTURE &&
setup->mask.texture.attributes.has_component_alpha;
/* Do various magic for component alpha */
if (component_alpha) {
status = _cairo_gl_composite_begin_component_alpha (ctx, setup);
if (unlikely (status))
goto FAIL;
} else {
if (ctx->pre_shader) {
_cairo_gl_composite_flush (ctx);
ctx->pre_shader = NULL;
}
}
status = _cairo_gl_get_shader_by_type (ctx,
&setup->src,
&setup->mask,
setup->spans,
component_alpha ?
CAIRO_GL_SHADER_IN_CA_SOURCE :
CAIRO_GL_SHADER_IN_NORMAL,
&shader);
if (unlikely (status)) {
ctx->pre_shader = NULL;
goto FAIL;
}
if (ctx->current_shader != shader)
_cairo_gl_composite_flush (ctx);
status = CAIRO_STATUS_SUCCESS;
dst_size = 2 * sizeof (GLfloat);
src_size = _cairo_gl_operand_get_vertex_size (&setup->src);
mask_size = _cairo_gl_operand_get_vertex_size (&setup->mask);
vertex_size = dst_size + src_size + mask_size;
if (setup->spans)
vertex_size += sizeof (GLfloat);
_cairo_gl_composite_setup_vbo (ctx, vertex_size);
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_SOURCE, &setup->src, vertex_size, dst_size);
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_MASK, &setup->mask, vertex_size, dst_size + src_size);
if (setup->spans)
_cairo_gl_context_setup_spans (ctx, vertex_size, dst_size + src_size + mask_size);
else {
ctx->dispatch.DisableVertexAttribArray (CAIRO_GL_COVERAGE_ATTRIB_INDEX);
ctx->spans = FALSE;
}
/* XXX: Shoot me - we have converted CLEAR to DEST_OUT,
so the dst_factor would be GL_ONE_MINUS_SRC_ALPHA, if the
mask is a surface and mask content not content_alpha, we want to use
GL_ONE_MINUS_SRC_COLOR, otherwise, we use GL_ONE_MINUS_SRC_ALPHA
*/
if (setup->mask.type == CAIRO_GL_OPERAND_TEXTURE)
mask_surface = &setup->mask.texture.surface->base;
if (op == CAIRO_OPERATOR_CLEAR &&
component_alpha &&
mask_surface != NULL &&
cairo_surface_get_content (mask_surface) == CAIRO_CONTENT_ALPHA)
component_alpha = FALSE;
_cairo_gl_set_operator (ctx, setup->op, component_alpha);
if (_cairo_gl_context_is_flushed (ctx)) {
if (ctx->pre_shader) {
_cairo_gl_set_shader (ctx, ctx->pre_shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
}
_cairo_gl_set_shader (ctx, shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
}
status = _cairo_gl_composite_setup_clipping (setup, ctx, vertex_size);
if (unlikely (status))
goto FAIL;
*ctx_out = ctx;
FAIL:
if (unlikely (status))
status = _cairo_gl_context_release (ctx, status);
return status;
}
cairo_status_t
_cairo_gl_composite_begin (cairo_gl_composite_t *setup,
cairo_gl_context_t **ctx_out)
{
unsigned int dst_size, src_size, mask_size, vertex_size;
cairo_gl_context_t *ctx;
cairo_status_t status;
cairo_bool_t component_alpha;
cairo_gl_shader_t *shader;
assert (setup->dst);
status = _cairo_gl_context_acquire (setup->dst->base.device, &ctx);
if (unlikely (status))
return status;
_cairo_gl_context_set_destination (ctx, setup->dst, setup->multisample);
glEnable (GL_BLEND);
component_alpha =
setup->mask.type == CAIRO_GL_OPERAND_TEXTURE &&
setup->mask.texture.attributes.has_component_alpha;
/* Do various magic for component alpha */
if (component_alpha) {
status = _cairo_gl_composite_begin_component_alpha (ctx, setup);
if (unlikely (status))
goto FAIL;
} else {
if (ctx->pre_shader) {
_cairo_gl_composite_flush (ctx);
ctx->pre_shader = NULL;
}
}
status = _cairo_gl_get_shader_by_type (ctx,
&setup->src,
&setup->mask,
setup->spans,
component_alpha ?
CAIRO_GL_SHADER_IN_CA_SOURCE :
CAIRO_GL_SHADER_IN_NORMAL,
&shader);
if (unlikely (status)) {
ctx->pre_shader = NULL;
goto FAIL;
}
if (ctx->current_shader != shader)
_cairo_gl_composite_flush (ctx);
status = CAIRO_STATUS_SUCCESS;
dst_size = 2 * sizeof (GLfloat);
src_size = _cairo_gl_operand_get_vertex_size (setup->src.type);
mask_size = _cairo_gl_operand_get_vertex_size (setup->mask.type);
vertex_size = dst_size + src_size + mask_size;
if (setup->spans)
vertex_size += sizeof (GLfloat);
_cairo_gl_composite_setup_vbo (ctx, vertex_size);
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_SOURCE, &setup->src, vertex_size, dst_size);
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_MASK, &setup->mask, vertex_size, dst_size + src_size);
_cairo_gl_context_setup_spans (ctx, setup->spans, vertex_size,
dst_size + src_size + mask_size);
_cairo_gl_set_operator (ctx, setup->op, component_alpha);
if (_cairo_gl_context_is_flushed (ctx)) {
if (ctx->pre_shader) {
_cairo_gl_set_shader (ctx, ctx->pre_shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
}
_cairo_gl_set_shader (ctx, shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
}
status = _cairo_gl_composite_setup_clipping (setup, ctx, vertex_size);
if (unlikely (status))
goto FAIL;
*ctx_out = ctx;
FAIL:
if (unlikely (status))
status = _cairo_gl_context_release (ctx, status);
return status;
}
cairo_status_t
_cairo_gl_set_operands_and_operator (cairo_gl_composite_t *setup,
cairo_gl_context_t *ctx)
{
unsigned int dst_size, src_size, mask_size, vertex_size;
cairo_status_t status;
cairo_gl_shader_t *shader;
cairo_bool_t component_alpha;
cairo_bool_t vertex_size_changed;
component_alpha =
setup->mask.type == CAIRO_GL_OPERAND_TEXTURE &&
setup->mask.texture.attributes.has_component_alpha;
/* Do various magic for component alpha */
if (component_alpha) {
status = _cairo_gl_composite_begin_component_alpha (ctx, setup);
if (unlikely (status))
return status;
} else {
if (ctx->pre_shader) {
_cairo_gl_composite_flush (ctx);
ctx->pre_shader = NULL;
}
}
status = _cairo_gl_get_shader_by_type (ctx,
&setup->src,
&setup->mask,
setup->spans,
component_alpha ?
CAIRO_GL_SHADER_IN_CA_SOURCE :
CAIRO_GL_SHADER_IN_NORMAL,
&shader);
if (unlikely (status)) {
ctx->pre_shader = NULL;
return status;
}
if (ctx->current_shader != shader)
_cairo_gl_composite_flush (ctx);
status = CAIRO_STATUS_SUCCESS;
dst_size = 2 * sizeof (GLfloat);
src_size = _cairo_gl_operand_get_vertex_size (&setup->src);
mask_size = _cairo_gl_operand_get_vertex_size (&setup->mask);
vertex_size = dst_size + src_size + mask_size;
if (setup->spans)
vertex_size += sizeof (GLfloat);
vertex_size_changed = _cairo_gl_composite_setup_vbo (ctx, vertex_size);
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_SOURCE, &setup->src, dst_size, vertex_size_changed);
_cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_MASK, &setup->mask, dst_size + src_size, vertex_size_changed);
_cairo_gl_context_setup_spans (ctx, setup->spans, vertex_size,
dst_size + src_size + mask_size);
_cairo_gl_set_operator (ctx, setup->op, component_alpha);
if (_cairo_gl_context_is_flushed (ctx)) {
if (ctx->pre_shader) {
_cairo_gl_set_shader (ctx, ctx->pre_shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
}
_cairo_gl_set_shader (ctx, shader);
_cairo_gl_composite_bind_to_shader (ctx, setup);
}
return status;
}
