swung0x48/MobileGL
1
0
Fork 0
mirror of https://github.com/MobileGL-Dev/MobileGL synced 2026-09-09 20:58:31 +09:00
Code Issues Packages Projects Releases Wiki Activity

[Feat] (MG_State, MG_Impl, DirectGLES): transform feedback objects, pause/resume and the special capture names

Browse Source 
GL 4.0 folds ARB_transform_feedback2 and _3 into core, and neither existed:
glGenTransformFeedbacks, glBindTransformFeedback, glDeleteTransformFeedbacks,
glIsTransformFeedback, glPause/ResumeTransformFeedback, the whole
glDrawTransformFeedback family and glBegin/EndQueryIndexed were all stubs, and
gl_NextBuffer / gl_SkipComponents1..4 failed the link as "not an output of the vertex
stage". Seven KHR-GL40.transform_feedback* cases failed on it, three of them by
leaving a capture open at deinit and taking the process down.

Objects. The capture state and the indexed GL_TRANSFORM_FEEDBACK_BUFFER bindings are
object state, but the context keeps one live copy of both, which is what every
existing reader - each backend's per-draw sync, the drawing and getter paths - is
written against. Rather than teach all of them about objects, a bind saves the live
copy into the outgoing object and restores the incoming one's. Object 0 is the
default object and needs no seeding; operator[] materialises the rest on first touch.

Pause. A paused span captures nothing, and three rules key off that: a draw is exempt
from the capture primitive-mode match, it feeds PRIMITIVES_GENERATED but not
TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN, and glUseProgram is allowed again (that last
one was already refused for an active capture, correctly for GL 3.3, which has no
pause).

glDrawTransformFeedback replays the vertices the object captured in its last completed
span, recorded at End. "Has a completed span" is tracked separately from that count,
because a completed empty span draws nothing while an object that never ended one is
INVALID_OPERATION. Drawing from the object whose capture is currently open is
deliberately allowed - feeding a result straight into the next span is the point of
KHR-GL40.transform_feedback.draw_xfb_feedbackk_test.

DirectGLES gets a real driver object per frontend object. That is the only reason the
default one would not do: several objects can be paused at once, and a paused span
lives inside the driver's object. The deferred driver-side Begin (still needed - ES
wants the program current and the buffers bound) now also has to be held back while
the span is paused, or a pause taken before the first draw would open the span on that
draw and subject it to the primitive-mode rule it is exempt from.

Special names. gl_NextBuffer and gl_SkipComponents<n> are consumed during varying
resolution and never become varyings of their own, so they only move where the
following ones land - and stay out of the name list the backend declares on its own
driver. ES cannot express the resulting layout at all: it packs every captured varying
into one gap-free record. So when the layout has holes or spans several buffers,
DirectGLES captures into a scratch buffer bound in place of the application's, and
End distributes the records to the offsets GL asked for. Only the bytes a varying
occupies are written, which is exactly what makes the holes keep the contents the
application left there - the property KHR-GL40.transform_feedback3.skip_components
checks.

glBegin/EndQueryIndexed and glGetQueryIndexediv differ from the plain forms only in the
vertex stream they address, so they validate the index and forward. GL_MAX_VERTEX_STREAMS
stays at 1: multi-stream capture needs ARB_gpu_shader5 stream qualifiers that no ES
driver implements, and the CTS cases that need more than one stream check the limit and
skip.

KHR-GL40.transform_feedback, transform_feedback2 and transform_feedback3: 38/38.
This commit is contained in:
BZLZHH
2026-08-04 10:18:53 -04:00
parent 8d1a734c22
commit 76f37a18e6
15 changed files with 746 additions and 76 deletions
Download Patch File Download Diff File Expand all files Collapse all files
MobileGL/MG_Impl/GLImpl/Drawing/GL_Drawing.cpp
+181 -2
View File
@@ -72,6 +72,9 @@ namespace MobileGL::MG_Impl::GLImpl {
// Geometry amplification is not modelled here.
static void AccountTransformFeedbackPrimitives(GLenum mode, GLsizei count) {
if (!MG_State::pGLContext->IsTransformFeedbackActive()) return;
// A paused span captures nothing, so a draw made while paused contributes to
// PRIMITIVES_GENERATED but not to TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN.
if (MG_State::pGLContext->IsTransformFeedbackPaused()) return;
Uint64 primitives = CountPrimitivesForDraw(mode, count);
if (primitives == 0) return;
MG_State::pGLContext->AddTransformFeedbackInputPrimitives(primitives);
@@ -202,8 +205,11 @@ namespace MobileGL::MG_Impl::GLImpl {
// While transform feedback is active the draw's primitive type must match
// the feedback primitive mode (GL 3.3 core 13.2.2). With a geometry shader
// the constraint moves to the shader's output primitive type instead, so
// the draw mode itself is unconstrained here.
// the draw mode itself is unconstrained here. A paused span is exempt: it
// captures nothing, so there is nothing for the mode to be incompatible with
// (GL 4.6 core 13.2.3).
if (MG_State::pGLContext->IsTransformFeedbackActive() &&
!MG_State::pGLContext->IsTransformFeedbackPaused() &&
!(MG_State::pGLContext->GetTransformFeedbackProgram() &&
MG_State::pGLContext->GetTransformFeedbackProgram()->GetShaderIndexByStage(ShaderStage::Geometry) >= 0)) {
const GLenum feedbackMode = MG_State::pGLContext->GetTransformFeedbackPrimitiveMode();
@@ -684,9 +690,12 @@ namespace MobileGL::MG_Impl::GLImpl {
"No program with transform feedback varyings is active."));
return;
}
// Every capture buffer slot the program's mode uses must have a buffer bound.
// Every capture buffer slot the program's mode uses must have a buffer bound. A slot
// of stride 0 - two consecutive gl_NextBuffer entries - captures nothing and so needs
// no binding.
const SizeT usedBufferCount = program->GetTransformFeedbackBufferCount();
for (SizeT i = 0; i < usedBufferCount; ++i) {
if (program->GetTransformFeedbackStride(static_cast<Uint32>(i)) == 0) continue;
const auto& point = MG_State::pGLContext->GetBufferBindingPoint(BufferTarget::TransformFeedback,
static_cast<Uint>(i));
if (point.GetBoundObject() == nullptr) {
@@ -800,4 +809,174 @@ namespace MobileGL::MG_Impl::GLImpl {
FixupGsStripCaptureOrder(capturedProgram, inputPrimitives);
}
void PauseTransformFeedback(void) {
if (!MG_State::pGLContext->IsTransformFeedbackActive() ||
MG_State::pGLContext->IsTransformFeedbackPaused()) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidOperation,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
"Transform feedback is not active, or is already paused."));
return;
}
MG_State::pGLContext->SetTransformFeedbackPaused(true);
if (const auto pauseXfb = MG_Backend::gBackendFunctionsTable.GL.PauseTransformFeedback) {
pauseXfb();
}
}
void ResumeTransformFeedback(void) {
if (!MG_State::pGLContext->IsTransformFeedbackActive() ||
!MG_State::pGLContext->IsTransformFeedbackPaused()) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidOperation,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__, "Transform feedback is not paused."));
return;
}
MG_State::pGLContext->SetTransformFeedbackPaused(false);
if (const auto resumeXfb = MG_Backend::gBackendFunctionsTable.GL.ResumeTransformFeedback) {
resumeXfb();
}
}
void GenTransformFeedbacks(GLsizei n, GLuint* ids) {
if (n < 0) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidValue,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__, "n must be non-negative."));
return;
}
if (n == 0 || ids == nullptr) return;
Vector<Uint> names;
MG_State::pGLContext->GenTransformFeedbackNames(static_cast<Uint>(n), names);
Memcpy(ids, names.data(), static_cast<SizeT>(n) * sizeof(GLuint));
}
void DeleteTransformFeedbacks(GLsizei n, const GLuint* ids) {
if (n < 0) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidValue,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__, "n must be non-negative."));
return;
}
if (ids == nullptr) return;
for (GLsizei i = 0; i < n; ++i) {
const GLuint id = ids[i];
// Unknown names and 0 are silently ignored; an object whose capture span is
// still open is not (GL 4.6 core 13.2.1).
if (id == 0 || !MG_State::pGLContext->ValidateTransformFeedbackName(id)) continue;
if (id == MG_State::pGLContext->GetBoundTransformFeedbackName() &&
MG_State::pGLContext->IsTransformFeedbackActive()) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidOperation,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
"Cannot delete a transform feedback object whose capture is active."));
continue;
}
if (const auto deleteXfb = MG_Backend::gBackendFunctionsTable.GL.DeleteTransformFeedback) {
deleteXfb(id);
}
MG_State::pGLContext->MarkTransformFeedbackObjectForDeletion(id);
}
}
void BindTransformFeedback(GLenum target, GLuint id) {
if (target != GL_TRANSFORM_FEEDBACK) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidEnum,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__, "target must be GL_TRANSFORM_FEEDBACK."));
return;
}
// A running capture pins its object; only a paused one may be swapped out.
if (MG_State::pGLContext->IsTransformFeedbackActive() &&
!MG_State::pGLContext->IsTransformFeedbackPaused()) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidOperation,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
"Transform feedback is active and not paused."));
return;
}
if (!MG_State::pGLContext->ValidateTransformFeedbackName(id)) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidOperation,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
std::to_string(id) + " is not a transform feedback object name."));
return;
}
MG_State::pGLContext->BindTransformFeedbackObject(id);
if (const auto bindXfb = MG_Backend::gBackendFunctionsTable.GL.BindTransformFeedback) {
bindXfb(id);
}
}
GLboolean IsTransformFeedback(GLuint id) {
// Name 0 is the default object, which glIsTransformFeedback reports as not an object.
return (id != 0 && MG_State::pGLContext->ValidateTransformFeedbackName(id)) ? GL_TRUE : GL_FALSE;
}
// glDrawTransformFeedback[Stream][Instanced]: replays the vertices the named object
// captured in its last completed span, as if by glDrawArraysInstanced with that count
// (GL 4.6 core 10.3.7).
static void DrawTransformFeedbackImpl(const char* functionName, GLenum mode, GLuint id, GLuint stream,
GLsizei instancecount) {
if (!ValidateCurrentProgramForExecution(functionName)) return;
if (!ValidatePrimitiveModeForBackend(functionName, mode)) return;
if (instancecount < 0) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidValue,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName, "instancecount must be non-negative."));
return;
}
if (!MG_State::pGLContext->ValidateTransformFeedbackName(id)) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidValue,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName,
std::to_string(id) + " is not a transform feedback object name."));
return;
}
// GL_MAX_VERTEX_STREAMS is 1, so stream 0 is the only one that exists.
if (stream != 0) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidValue,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName,
"stream must be less than GL_MAX_VERTEX_STREAMS."));
return;
}
// Drawing from an object whose capture is currently open is legal and deliberate:
// it is how a transform feedback result is fed straight back into the next span
// (ARB_transform_feedback2 lists no such restriction).
if (!MG_State::pGLContext->HasTransformFeedbackCompletedSpan(id)) {
MG_State::pGLContext->RecordError(
ErrorCode::InvalidOperation,
MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName,
"glEndTransformFeedback has never been called for this object."));
return;
}
const Uint64 vertices = MG_State::pGLContext->GetTransformFeedbackRecordedVertices(id);
if (vertices == 0) return;
const auto count = static_cast<GLsizei>(vertices);
AccountTransformFeedbackPrimitives(mode, count);
if (instancecount == 1) {
DrawArrays_Backend(mode, 0, count);
} else {
DrawArraysInstanced_Backend(mode, 0, count, instancecount);
}
}
void DrawTransformFeedback(GLenum mode, GLuint id) {
DrawTransformFeedbackImpl(__func__, mode, id, 0, 1);
}
void DrawTransformFeedbackInstanced(GLenum mode, GLuint id, GLsizei instancecount) {
DrawTransformFeedbackImpl(__func__, mode, id, 0, instancecount);
}
void DrawTransformFeedbackStream(GLenum mode, GLuint id, GLuint stream) {
DrawTransformFeedbackImpl(__func__, mode, id, stream, 1);
}
void DrawTransformFeedbackStreamInstanced(GLenum mode, GLuint id, GLuint stream, GLsizei instancecount) {
DrawTransformFeedbackImpl(__func__, mode, id, stream, instancecount);
}
} // namespace MobileGL::MG_Impl::GLImpl