Sets up stage bindings for single draw call in the OpenGLES backend. More...

#include <buffer_bindings_gles.h>

Public Member Functions
	BufferBindingsGLES ()

	~BufferBindingsGLES ()

bool	RegisterVertexStageInput (const ProcTableGLES &gl, const std::vector< ShaderStageIOSlot > &inputs, const std::vector< ShaderStageBufferLayout > &layouts)

bool	ReadUniformsBindings (const ProcTableGLES &gl, GLuint program)

bool	BindVertexAttributes (const ProcTableGLES &gl, size_t binding, size_t vertex_offset, size_t instance=0)

bool	BindUniformData (const ProcTableGLES &gl, const std::vector< TextureAndSampler > &bound_textures, const std::vector< BufferResource > &bound_buffers, Range texture_range, Range buffer_range)

bool	UnbindVertexAttributes (const ProcTableGLES &gl)

Detailed Description

Sets up stage bindings for single draw call in the OpenGLES backend.

Definition at line 30 of file buffer_bindings_gles.h.

Constructor & Destructor Documentation

◆ BufferBindingsGLES()

impeller::BufferBindingsGLES::BufferBindingsGLES ( )

default

◆ ~BufferBindingsGLES()

impeller::BufferBindingsGLES::~BufferBindingsGLES ( )

default

Member Function Documentation

◆ BindUniformData()

bool impeller::BufferBindingsGLES::BindUniformData	(	const ProcTableGLES &	gl,
		const std::vector< TextureAndSampler > &	bound_textures,
		const std::vector< BufferResource > &	bound_buffers,
		Range	texture_range,
		Range	buffer_range
	)

Definition at line 261 of file buffer_bindings_gles.cc.

                         {
   for (auto i = 0u; i < buffer_range.length; i++) {
     if (!BindUniformBuffer(gl, bound_buffers[buffer_range.offset + i])) {
       return false;
     }
   }
   std::optional<size_t> next_unit_index =
       BindTextures(gl, bound_textures, texture_range, ShaderStage::kVertex);
   if (!next_unit_index.has_value()) {
     return false;
   }
   if (!BindTextures(gl, bound_textures, texture_range, ShaderStage::kFragment,
                     *next_unit_index)
            .has_value()) {
     return false;
   }
  
   return true;
 }

References impeller::kFragment, impeller::kVertex, impeller::Range::length, and impeller::Range::offset.

Referenced by impeller::EncodeCommandsInReactor(), and impeller::testing::TEST().

◆ BindVertexAttributes()

bool impeller::BufferBindingsGLES::BindVertexAttributes	(	const ProcTableGLES &	gl,
		size_t	binding,
		size_t	vertex_offset,
		size_t	instance = `0`
	)

Bind the vertex attributes for buffer slot [binding].

[instance] re-points instance-rate attributes at the given instance, used to emulate an instanced draw on drivers without hardware instancing support. It is 0 for a non-instanced or hardware-instanced draw.

Definition at line 197 of file buffer_bindings_gles.cc.

                                                                {
   if (binding >= vertex_attrib_arrays_.size()) {
     return false;
   }
  
   // For an emulated instanced draw (instance > 0), a binding whose attributes
   // are all vertex-rate (divisor 0) does not change across instances, so the
   // state bound for instance 0 still applies. Skip the redundant re-binding.
   if (instance > 0u) {
     bool has_instance_rate = false;
     for (const auto& array : vertex_attrib_arrays_[binding]) {
       if (array.vertex_attrib_divisor != 0u) {
         has_instance_rate = true;
         break;
       }
     }
     if (!has_instance_rate) {
       return true;
     }
   }
  
   if (!gl.GetCapabilities()->IsES()) {
     FML_DCHECK(vertex_array_object_ == 0);
     gl.GenVertexArrays(1, &vertex_array_object_);
     gl.BindVertexArray(vertex_array_object_);
   }
  
   for (const auto& array : vertex_attrib_arrays_[binding]) {
     gl.EnableVertexAttribArray(array.index);
     // For an emulated instanced draw, an instance-rate attribute is
     // re-pointed at instance `instance`, since there is no hardware divisor
     // to advance it. A non-instanced or hardware-instanced draw passes
     // instance 0 and lets the divisor (if any) do the stepping.
     size_t attribute_offset = vertex_offset + array.offset;
     if (array.vertex_attrib_divisor != 0u) {
       attribute_offset += instance * static_cast<size_t>(array.stride);
     }
     gl.VertexAttribPointer(array.index,       // index
                            array.size,        // size (must be 1, 2, 3, or 4)
                            array.type,        // type
                            array.normalized,  // normalized
                            array.stride,      // stride
                            reinterpret_cast<const GLvoid*>(
                                static_cast<uintptr_t>(attribute_offset))  // ptr
     );
     // Set the instancing divisor when the driver supports it. It is core
     // on ES 3.0+ and comes from GL_EXT_instanced_arrays on ES 2.0. When
     // unavailable, only per-vertex (divisor 0) bindings are possible,
     // which is the default. Setting it for every attribute (including
     // divisor 0) also clears any stale divisor left by a prior pipeline,
     // which matters on ES, where there is no vertex array object.
     if (gl.VertexAttribDivisor.IsAvailable()) {
       gl.VertexAttribDivisor(array.index, array.vertex_attrib_divisor);
     } else if (gl.VertexAttribDivisorEXT.IsAvailable()) {
       gl.VertexAttribDivisorEXT(array.index, array.vertex_attrib_divisor);
     }
   }
  
   return true;
 }

References impeller::ProcTableGLES::GetCapabilities().

Referenced by impeller::BindVertexBuffer(), and impeller::testing::TEST().

◆ ReadUniformsBindings()

bool impeller::BufferBindingsGLES::ReadUniformsBindings	(	const ProcTableGLES &	gl,
		GLuint	program
	)

Definition at line 104 of file buffer_bindings_gles.cc.

                                                               {
   if (!gl.IsProgram(program)) {
     return false;
   }
   program_handle_ = program;
   if (gl.GetDescription()->GetGlVersion().IsAtLeast(Version{3, 0, 0})) {
     return ReadUniformsBindingsV3(gl, program);
   }
   return ReadUniformsBindingsV2(gl, program);
 }

References impeller::ProcTableGLES::GetDescription(), impeller::DescriptionGLES::GetGlVersion(), and impeller::Version::IsAtLeast().

◆ RegisterVertexStageInput()

bool impeller::BufferBindingsGLES::RegisterVertexStageInput	(	const ProcTableGLES &	gl,
		const std::vector< ShaderStageIOSlot > &	inputs,
		const std::vector< ShaderStageBufferLayout > &	layouts
	)

Definition at line 32 of file buffer_bindings_gles.cc.

                                                        {
   std::vector<std::vector<VertexAttribPointer>> vertex_attrib_arrays(
       layouts.size());
   // Every layout corresponds to a vertex binding.
   // As we record, separate the attributes into buckets for each layout in
   // ascending order. We do this because later on, we'll need to associate each
   // of the attributes with bound buffers corresponding to the binding.
   for (auto layout_i = 0u; layout_i < layouts.size(); layout_i++) {
     const auto& layout = layouts[layout_i];
     for (const auto& input : p_inputs) {
       if (input.binding != layout_i) {
         continue;
       }
       VertexAttribPointer attrib;
       attrib.index = input.location;
       // Component counts must be 1, 2, 3 or 4. Do that validation now.
       if (input.vec_size < 1u || input.vec_size > 4u) {
         return false;
       }
       attrib.size = input.vec_size;
       auto type = ToVertexAttribType(input.GetVertexAttributeFormat());
       if (!type.has_value()) {
         return false;
       }
       attrib.type = type.value();
       attrib.normalized = GL_FALSE;
       attrib.offset = input.offset;
       attrib.stride = layout.stride;
       attrib.vertex_attrib_divisor =
           layout.input_rate == VertexInputRate::kInstance ? 1u : 0u;
       vertex_attrib_arrays[layout_i].push_back(attrib);
     }
   }
   vertex_attrib_arrays_ = std::move(vertex_attrib_arrays);
   return true;
 }

References impeller::kInstance, and impeller::ToVertexAttribType().

Referenced by impeller::testing::TEST().

◆ UnbindVertexAttributes()

bool impeller::BufferBindingsGLES::UnbindVertexAttributes ( const ProcTableGLES & gl )

Definition at line 286 of file buffer_bindings_gles.cc.

                                                                        {
   for (const auto& array : vertex_attrib_arrays_) {
     for (const auto& attribute : array) {
       gl.DisableVertexAttribArray(attribute.index);
     }
   }
   if (!gl.GetCapabilities()->IsES()) {
     gl.DeleteVertexArrays(1, &vertex_array_object_);
     vertex_array_object_ = 0;
   }
  
   return true;
 }