void
brw_begin_transform_feedback(struct gl_context *ctx, GLenum mode,
struct gl_transform_feedback_object *obj)
{
struct brw_context *brw = brw_context(ctx);
const struct gl_shader_program *shaderprog;
const struct gl_transform_feedback_info *linked_xfb_info;
struct gl_transform_feedback_object *xfb_obj =
ctx->TransformFeedback.CurrentObject;
assert(brw->gen == 6);
if (brw->geometry_program) {
/* BRW_NEW_GEOMETRY_PROGRAM */
shaderprog =
ctx->_Shader->CurrentProgram[MESA_SHADER_GEOMETRY];
} else {
/* BRW_NEW_VERTEX_PROGRAM */
shaderprog =
ctx->_Shader->CurrentProgram[MESA_SHADER_VERTEX];
}
linked_xfb_info = &shaderprog->LinkedTransformFeedback;
/* Compute the maximum number of vertices that we can write without
* overflowing any of the buffers currently being used for feedback.
*/
unsigned max_index
= _mesa_compute_max_transform_feedback_vertices(xfb_obj,
linked_xfb_info);
/* 3DSTATE_GS_SVB_INDEX is non-pipelined. */
intel_emit_post_sync_nonzero_flush(brw);
/* Initialize the SVBI 0 register to zero and set the maximum index. */
BEGIN_BATCH(4);
OUT_BATCH(_3DSTATE_GS_SVB_INDEX << 16 | (4 - 2));
OUT_BATCH(0); /* SVBI 0 */
OUT_BATCH(0); /* starting index */
OUT_BATCH(max_index);
ADVANCE_BATCH();
/* Initialize the rest of the unused streams to sane values. Otherwise,
* they may indicate that there is no room to write data and prevent
* anything from happening at all.
*/
for (int i = 1; i < 4; i++) {
BEGIN_BATCH(4);
OUT_BATCH(_3DSTATE_GS_SVB_INDEX << 16 | (4 - 2));
OUT_BATCH(i << SVB_INDEX_SHIFT);
OUT_BATCH(0); /* starting index */
OUT_BATCH(0xffffffff);
ADVANCE_BATCH();
}
}
void GLAPIENTRY
_mesa_BeginTransformFeedback(GLenum mode)
{
struct gl_transform_feedback_object *obj;
struct gl_transform_feedback_info *info = NULL;
struct gl_shader_program *source;
GLuint i;
unsigned vertices_per_prim;
GET_CURRENT_CONTEXT(ctx);
obj = ctx->TransformFeedback.CurrentObject;
/* Figure out what pipeline stage is the source of data for transform
* feedback.
*/
source = get_xfb_source(ctx);
if (source == NULL) {
_mesa_error(ctx, GL_INVALID_OPERATION,
"glBeginTransformFeedback(no program active)");
return;
}
info = &source->LinkedTransformFeedback;
if (info->NumOutputs == 0) {
_mesa_error(ctx, GL_INVALID_OPERATION,
"glBeginTransformFeedback(no varyings to record)");
return;
}
switch (mode) {
case GL_POINTS:
vertices_per_prim = 1;
break;
case GL_LINES:
vertices_per_prim = 2;
break;
case GL_TRIANGLES:
vertices_per_prim = 3;
break;
default:
_mesa_error(ctx, GL_INVALID_ENUM, "glBeginTransformFeedback(mode)");
return;
}
if (obj->Active) {
_mesa_error(ctx, GL_INVALID_OPERATION,
"glBeginTransformFeedback(already active)");
return;
}
for (i = 0; i < info->NumBuffers; ++i) {
if (obj->BufferNames[i] == 0) {
_mesa_error(ctx, GL_INVALID_OPERATION,
"glBeginTransformFeedback(binding point %d does not have "
"a buffer object bound)", i);
return;
}
}
FLUSH_VERTICES(ctx, 0);
ctx->NewDriverState |= ctx->DriverFlags.NewTransformFeedback;
obj->Active = GL_TRUE;
ctx->TransformFeedback.Mode = mode;
compute_transform_feedback_buffer_sizes(obj);
if (_mesa_is_gles3(ctx)) {
/* In GLES3, we are required to track the usage of the transform
* feedback buffer and report INVALID_OPERATION if a draw call tries to
* exceed it. So compute the maximum number of vertices that we can
* write without overflowing any of the buffers currently being used for
* feedback.
*/
unsigned max_vertices
= _mesa_compute_max_transform_feedback_vertices(obj, info);
obj->GlesRemainingPrims = max_vertices / vertices_per_prim;
}
if (obj->shader_program != source) {
ctx->NewDriverState |= ctx->DriverFlags.NewTransformFeedbackProg;
obj->shader_program = source;
}
assert(ctx->Driver.BeginTransformFeedback);
ctx->Driver.BeginTransformFeedback(ctx, mode, obj);
}
