[v11,03/24] libcamera: software_isp: egl: Add a eGL base helper class
diff mbox series

Message ID 20260106170059.56193-4-bryan.odonoghue@linaro.org
State Accepted
Commit 99fd2e669ce305374952018f42031f34483c035f
Headers show
Series
  • Add GLES 2.0 GPUISP to libcamera
Related show

Commit Message

Bryan O'Donoghue Jan. 6, 2026, 5 p.m. UTC
Introduce an eGL base helper class which provides an eGL context based on a
passed width and height.

The initGLContext function could be overloaded to provide an interface to a
real display.

A set of helper functions is provided to compile and link GLSL shaders.
linkShaderProgram currently compiles vertex/fragment pairs but could be
overloaded or passed a parameter to link a compute shader instead.

Breaking the eGL interface away from debayering - allows to use the eGL
context inside of a dma-buf heap cleanly, reuse that context inside of a
debayer layer and conceivably reuse the context in a multi-stage shader
pass.

Small note the image_attrs[] array doesn't pass checkstyle.py however the
elements of the array are in pairs.

Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
[bod: Takes fix from Hans for constructor stride bpp]
[bod: Drops eglClientWaitSync in favour of glFinish Robert/Milan]
Co-developed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Co-developed-by: Milan Zamazal <mzamazal@redhat.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Robert Mader <robert.mader@collabora.com>
Tested-by: Hans de Goede <johannes.goede@qualcomm.com> # ThinkPad T14s gen 6 (arm64) ov02c10 + X1c gen 12 ov08x40
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
 include/libcamera/internal/egl.h       | 152 +++++++
 include/libcamera/internal/meson.build |   1 +
 src/libcamera/egl.cpp                  | 608 +++++++++++++++++++++++++
 src/libcamera/meson.build              |  23 +
 4 files changed, 784 insertions(+)
 create mode 100644 include/libcamera/internal/egl.h
 create mode 100644 src/libcamera/egl.cpp

Patch
diff mbox series

diff --git a/include/libcamera/internal/egl.h b/include/libcamera/internal/egl.h
new file mode 100644
index 000000000..a92921123
--- /dev/null
+++ b/include/libcamera/internal/egl.h
@@ -0,0 +1,152 @@ 
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Linaro Ltd.
+ *
+ * Authors:
+ * Bryan O'Donoghue <bryan.odonoghue@linaro.org>
+ *
+ */
+
+#pragma once
+
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/span.h>
+#include <libcamera/base/utils.h>
+
+#include "libcamera/internal/gbm.h"
+
+#define EGL_EGLEXT_PROTOTYPES
+#include <EGL/egl.h>
+#include <EGL/eglext.h>
+#define GL_GLEXT_PROTOTYPES
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+namespace libcamera {
+
+LOG_DECLARE_CATEGORY(eGL)
+
+/**
+ * \class eGLImage
+ * \brief Helper class for managing EGL image resources
+ *
+ * The eGLImage class encapsulates OpenGL ES texture and framebuffer objects
+ * along with their associated EGL image. It aggregates handles, descriptors,
+ * and routines for managing textures that can be associated with shader
+ * uniform IDs.
+ *
+ * This class is particularly useful for managing DMA-BUF backed textures
+ * in zero-copy rendering pipelines, where textures are bound to specific
+ * texture units and can be used as both input textures and render targets.
+ */
+class eGLImage
+{
+public:
+	/**
+	 * \brief Construct an eGLImage with explicit stride
+	 * \param[in] width Image width in pixels
+	 * \param[in] height Image height in pixels
+	 * \param[in] bpp Bytes per pixel
+	 * \param[in] stride Row stride in bytes
+	 * \param[in] texture_unit OpenGL texture unit
+	 * \param[in] texture_unit_uniform_id Shader uniform ID
+	 */
+	eGLImage(uint32_t width, uint32_t height, uint32_t bpp, uint32_t stride, GLenum texture_unit, uint32_t texture_unit_uniform_id)
+		: width_(width), height_(height), stride_(stride),
+		  framesize_(stride * height), bpp_(bpp),
+		  texture_unit_uniform_id_(texture_unit_uniform_id),
+		  texture_unit_(texture_unit)
+	{
+		glGenTextures(1, &texture_);
+		glGenFramebuffers(1, &fbo_);
+	}
+
+	/**
+	 * \brief Construct an eGLImage with automatic stride calculation
+	 */
+	eGLImage(uint32_t width, uint32_t height, uint32_t bpp, GLenum texture_unit, uint32_t texture_unit_uniform_id)
+		: eGLImage(width, height, bpp, utils::alignUp(width * bpp / 8, 256),
+			   texture_unit, texture_unit_uniform_id)
+	{
+	}
+
+	/**
+	 * \brief Destroy the eGLImage
+	 *
+	 * Cleans up OpenGL resources by deleting the framebuffer object and
+	 * texture.
+	 */
+	~eGLImage()
+	{
+		glDeleteFramebuffers(1, &fbo_);
+		glDeleteTextures(1, &texture_);
+	}
+
+	uint32_t width_; /**< Image width in pixels */
+	uint32_t height_; /**< Image height in pixels */
+	uint32_t stride_; /**< Row stride in bytes */
+	uint32_t offset_; /**< Buffer offset (reserved for future use) */
+	uint32_t framesize_; /**< Total frame size in bytes (stride * height) */
+	uint32_t bpp_; /**< Bytes per pixel */
+	uint32_t texture_unit_uniform_id_; /**< Shader uniform id for texture unit */
+	GLenum texture_unit_; /**< Texture unit associated with this image eg (GL_TEXTURE0) */
+	GLuint texture_; /**< OpenGL texture object ID */
+	GLuint fbo_; /**< OpenGL frame buffer object ID */
+	EGLImageKHR image_; /**< EGL Image handle */
+
+private:
+	LIBCAMERA_DISABLE_COPY_AND_MOVE(eGLImage)
+};
+
+class eGL
+{
+public:
+	eGL();
+	~eGL();
+
+	int initEGLContext(GBM *gbmContext);
+	void cleanUp();
+
+	int createInputDMABufTexture2D(eGLImage &eglImage, int fd);
+	int createOutputDMABufTexture2D(eGLImage &eglImage, int fd);
+	void destroyDMABufTexture(eGLImage &eglImage);
+	void createTexture2D(eGLImage &eglImage, GLint format, uint32_t width, uint32_t height, void *data);
+
+	void pushEnv(std::vector<std::string> &shaderEnv, const char *str);
+	void makeCurrent();
+
+	int compileVertexShader(GLuint &shaderId, const unsigned char *shaderData,
+				unsigned int shaderDataLen,
+				Span<const std::string> shaderEnv);
+	int compileFragmentShader(GLuint &shaderId, const unsigned char *shaderData,
+				  unsigned int shaderDataLen,
+				  Span<const std::string> shaderEnv);
+	int linkProgram(GLuint &programId, GLuint fragmentshaderId, GLuint vertexshaderId);
+	void dumpShaderSource(GLuint shaderId);
+	void useProgram(GLuint programId);
+	void deleteProgram(GLuint programId);
+	void syncOutput();
+
+private:
+	LIBCAMERA_DISABLE_COPY_AND_MOVE(eGL)
+
+	pid_t tid_;
+
+	EGLDisplay display_ = EGL_NO_DISPLAY;
+	EGLContext context_ = EGL_NO_CONTEXT;
+	EGLSurface surface_ = EGL_NO_SURFACE;
+
+	int compileShader(int shaderType, GLuint &shaderId, const unsigned char *shaderData,
+			  unsigned int shaderDataLen,
+			  Span<const std::string> shaderEnv);
+
+	int createDMABufTexture2D(eGLImage &eglImage, int fd, bool output);
+
+	PFNGLEGLIMAGETARGETTEXTURE2DOESPROC glEGLImageTargetTexture2DOES;
+	PFNEGLCREATEIMAGEKHRPROC eglCreateImageKHR;
+	PFNEGLDESTROYIMAGEKHRPROC eglDestroyImageKHR;
+};
+} //namespace libcamera
diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
index b8324996b..dc48619e5 100644
--- a/include/libcamera/internal/meson.build
+++ b/include/libcamera/internal/meson.build
@@ -23,6 +23,7 @@  libcamera_internal_headers = files([
     'dma_buf_allocator.h',
     'formats.h',
     'framebuffer.h',
+    'egl.h',
     'gbm.h',
     'global_configuration.h',
     'ipa_data_serializer.h',
diff --git a/src/libcamera/egl.cpp b/src/libcamera/egl.cpp
new file mode 100644
index 000000000..0544056bd
--- /dev/null
+++ b/src/libcamera/egl.cpp
@@ -0,0 +1,608 @@ 
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Linaro Ltd.
+ *
+ * Authors:
+ * Bryan O'Donoghue <bryan.odonoghue@linaro.org>
+ *
+ */
+
+#include "libcamera/internal/egl.h"
+
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include <linux/dma-buf.h>
+#include <linux/dma-heap.h>
+
+#include <libcamera/base/thread.h>
+
+#include <libdrm/drm_fourcc.h>
+
+namespace libcamera {
+
+LOG_DEFINE_CATEGORY(eGL)
+
+/**
+ * \class eGL
+ * \brief Helper class for managing OpenGL ES operations
+ *
+ * It provides:
+ *
+ * - EGL context setup and management
+ * - Extension function pointer retrieval
+ * - Shader compilation and program linking
+ * - DMA-BUF texture creation and management
+ * - Synchronisation primitives
+ *
+ * This class is designed to work with zero-copy buffers via DMA-BUF file
+ * descriptors.
+ */
+
+/**
+ *\var eGL::tid_
+ *\brief Thread ID of the thread associated with this EGL context
+ */
+
+/**
+ *\var eGL::display_
+ *\brief EGL display handle
+ */
+
+/**
+ *\var eGL::context_
+ *\brief EGL context handle
+ */
+
+/**
+ *\var eGL::surface_
+ *\brief EGL sufrace handle
+ */
+
+/**
+ * \brief Construct an EGL helper
+ *
+ * Creates an eGL instance with uninitialised context. Call initEGLContext()
+ * to set up the EGL display, context, and load extension functions.
+ */
+eGL::eGL()
+{
+}
+
+/**
+ * \brief Destroy the EGL helper
+ *
+ * Destroys the EGL context and surface if they were successfully created.
+ */
+eGL::~eGL()
+{
+	if (context_ != EGL_NO_CONTEXT)
+		eglDestroyContext(display_, context_);
+
+	if (surface_ != EGL_NO_SURFACE)
+		eglDestroySurface(display_, surface_);
+}
+
+/**
+ * \brief Synchronise rendering output
+ *
+ * Sychronise here. Calls glFinish() right now.
+ *
+ */
+void eGL::syncOutput()
+{
+	ASSERT(tid_ == Thread::currentId());
+
+	glFinish();
+}
+
+/**
+ * \brief Create a DMA-BUF backed 2D texture
+ * \param[in,out] eglImage EGL image to associate with the DMA-BUF
+ * \param[in] fd DMA-BUF file descriptor
+ * \param[in] output If true, create framebuffer for render target
+ *
+ * Internal implementation for creating DMA-BUF textures. Creates an EGL
+ * image from the DMA-BUF and binds it to a 2D texture. If output is true,
+ * also creates and attaches a framebuffer object.
+ *
+ * \return 0 on success, or -ENODEV on failure
+ */
+int eGL::createDMABufTexture2D(eGLImage &eglImage, int fd, bool output)
+{
+	int ret = 0;
+
+	ASSERT(tid_ == Thread::currentId());
+
+	// clang-format off
+	EGLint image_attrs[] = {
+		EGL_WIDTH, (EGLint)eglImage.width_,
+		EGL_HEIGHT, (EGLint)eglImage.height_,
+		EGL_LINUX_DRM_FOURCC_EXT, DRM_FORMAT_ARGB8888,
+		EGL_DMA_BUF_PLANE0_FD_EXT, fd,
+		EGL_DMA_BUF_PLANE0_OFFSET_EXT, 0,
+		EGL_DMA_BUF_PLANE0_PITCH_EXT, (EGLint)eglImage.stride_,
+		EGL_DMA_BUF_PLANE0_MODIFIER_LO_EXT, 0,
+		EGL_DMA_BUF_PLANE0_MODIFIER_HI_EXT, 0,
+		EGL_NONE,
+	};
+	// clang-format on
+
+	eglImage.image_ = eglCreateImageKHR(display_, EGL_NO_CONTEXT,
+					    EGL_LINUX_DMA_BUF_EXT,
+					    NULL, image_attrs);
+
+	if (eglImage.image_ == EGL_NO_IMAGE_KHR) {
+		LOG(eGL, Error) << "eglCreateImageKHR fail";
+		ret = -ENODEV;
+		goto done;
+	}
+
+	// Bind texture unit and texture
+	glActiveTexture(eglImage.texture_unit_);
+	glBindTexture(GL_TEXTURE_2D, eglImage.texture_);
+
+	// Generate texture with filter semantics
+	glEGLImageTargetTexture2DOES(GL_TEXTURE_2D, eglImage.image_);
+
+	// Nearest filtering
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+	// Wrap to edge to avoid edge artifacts
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
+	if (output) {
+		// Generate a framebuffer from our texture direct to dma-buf handle buffer
+		glBindFramebuffer(GL_FRAMEBUFFER, eglImage.fbo_);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, eglImage.texture_, 0);
+
+		GLenum err = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+		if (err != GL_FRAMEBUFFER_COMPLETE) {
+			LOG(eGL, Error) << "glFrameBufferTexture2D error " << err;
+			eglDestroyImageKHR(display_, eglImage.image_);
+			ret = -ENODEV;
+			goto done;
+		}
+	}
+done:
+	return ret;
+}
+
+/**
+ * \brief Create an input DMA-BUF backed texture
+ * \param[in,out] eglImage EGL image to associate with the DMA-BUF
+ * \param[in] fd DMA-BUF file descriptor
+ *
+ * Creates an EGL image from a DMA-BUF file descriptor and binds it to
+ * a 2D texture for use as an input texture in shaders. The texture is
+ * configured with nearest filtering and clamp-to-edge wrapping.
+ *
+ * \return 0 on success, or -ENODEV on failure
+ */
+int eGL::createInputDMABufTexture2D(eGLImage &eglImage, int fd)
+{
+	ASSERT(tid_ == Thread::currentId());
+
+	return createDMABufTexture2D(eglImage, fd, false);
+}
+
+/**
+ * \brief Create an output DMA-BUF backed texture
+ * \param[in,out] eglImage EGL image to associate with the DMA-BUF
+ * \param[in] fd DMA-BUF file descriptor
+ *
+ * Creates an EGL image from a DMA-BUF file descriptor and binds it to
+ * a 2D texture, then attaches it to a framebuffer object for use as a
+ * render target. This enables zero-copy rendering directly to the
+ * DMA-BUF.
+ *
+ * \return 0 on success, or -ENODEV on failure
+ */
+int eGL::createOutputDMABufTexture2D(eGLImage &eglImage, int fd)
+{
+	ASSERT(tid_ == Thread::currentId());
+
+	return createDMABufTexture2D(eglImage, fd, true);
+}
+
+/**
+ * \brief Destroy a DMA-BUF texture's EGL image
+ * \param[in,out] eglImage EGL image to destroy
+ *
+ * Destroys the EGL image associated with a DMA-BUF texture. The OpenGL
+ * texture and framebuffer objects are destroyed separately in the
+ * eGLImage destructor.
+ */
+void eGL::destroyDMABufTexture(eGLImage &eglImage)
+{
+	eglDestroyImage(display_, std::exchange(eglImage.image_, EGL_NO_IMAGE_KHR));
+}
+
+/**
+ * \brief Create a 2D texture from a memory buffer
+ * \param[in,out] eglImage EGL image to associate with the texture
+ * \param[in] format OpenGL internal format (e.g., GL_RGB, GL_RGBA)
+ * \param[in] width Texture width in pixels
+ * \param[in] height Texture height in pixels
+ * \param[in] data Pointer to pixel data, or nullptr for uninitialised texture
+ *
+ * Creates a 2D texture from a CPU-accessible memory buffer. The texture
+ * is configured with nearest filtering and clamp-to-edge wrapping. This
+ * is useful for uploading static data like lookup tables or uniform color
+ * matrices to the GPU.
+ */
+void eGL::createTexture2D(eGLImage &eglImage, GLint format, uint32_t width, uint32_t height, void *data)
+{
+	ASSERT(tid_ == Thread::currentId());
+
+	glActiveTexture(eglImage.texture_unit_);
+	glBindTexture(GL_TEXTURE_2D, eglImage.texture_);
+
+	// Generate texture, bind, associate image to texture, configure, unbind
+	glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
+
+	// Nearest filtering
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+	// Wrap to edge to avoid edge artifacts
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+}
+
+/**
+ * \brief Initialise the EGL context
+ * \param[in] gbmContext Pointer to initialised GBM context
+ *
+ * Sets up the EGL display from the GBM device, creates an OpenGL ES 2.0
+ * context, and retrieves function pointers for required extensions
+ * including:
+ * - eglCreateImageKHR / eglDestroyImageKHR
+ * - glEGLImageTargetTexture2DOES
+ *
+ * \return 0 on success, or -ENODEV on failure
+ */
+int eGL::initEGLContext(GBM *gbmContext)
+{
+	EGLint configAttribs[] = {
+		EGL_RED_SIZE, 8,
+		EGL_GREEN_SIZE, 8,
+		EGL_BLUE_SIZE, 8,
+		EGL_ALPHA_SIZE, 8,
+		EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
+		EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
+		EGL_NONE
+	};
+
+	EGLint contextAttribs[] = {
+		EGL_CONTEXT_MAJOR_VERSION, 2,
+		EGL_NONE
+	};
+
+	EGLint numConfigs;
+	EGLConfig config;
+	EGLint major;
+	EGLint minor;
+
+	if (!eglBindAPI(EGL_OPENGL_ES_API)) {
+		LOG(eGL, Error) << "API bind fail";
+		goto fail;
+	}
+
+	display_ = eglGetDisplay(gbmContext->device());
+	if (display_ == EGL_NO_DISPLAY) {
+		LOG(eGL, Error) << "Unable to get EGL display";
+		goto fail;
+	}
+
+	if (eglInitialize(display_, &major, &minor) != EGL_TRUE) {
+		LOG(eGL, Error) << "eglInitialize fail";
+		goto fail;
+	}
+
+	LOG(eGL, Info) << "EGL: version " << major << "." << minor;
+	LOG(eGL, Info) << "EGL: EGL_VERSION: " << eglQueryString(display_, EGL_VERSION);
+	LOG(eGL, Info) << "EGL: EGL_VENDOR: " << eglQueryString(display_, EGL_VENDOR);
+	LOG(eGL, Info) << "EGL: EGL_CLIENT_APIS: " << eglQueryString(display_, EGL_CLIENT_APIS);
+	LOG(eGL, Info) << "EGL: EGL_EXTENSIONS: " << eglQueryString(display_, EGL_EXTENSIONS);
+
+	eglCreateImageKHR = (PFNEGLCREATEIMAGEKHRPROC)eglGetProcAddress("eglCreateImageKHR");
+	if (!eglCreateImageKHR) {
+		LOG(eGL, Error) << "eglCreateImageKHR not found";
+		goto fail;
+	}
+
+	eglDestroyImageKHR = (PFNEGLDESTROYIMAGEKHRPROC)eglGetProcAddress("eglDestroyImageKHR");
+	if (!eglDestroyImageKHR) {
+		LOG(eGL, Error) << "eglDestroyImageKHR not found";
+		goto fail;
+	}
+
+	glEGLImageTargetTexture2DOES = (PFNGLEGLIMAGETARGETTEXTURE2DOESPROC)eglGetProcAddress("glEGLImageTargetTexture2DOES");
+	if (!glEGLImageTargetTexture2DOES) {
+		LOG(eGL, Error) << "glEGLImageTargetTexture2DOES not found";
+		goto fail;
+	}
+
+	if (eglChooseConfig(display_, configAttribs, &config, 1, &numConfigs) != EGL_TRUE) {
+		LOG(eGL, Error) << "eglChooseConfig fail";
+		goto fail;
+	}
+
+	context_ = eglCreateContext(display_, config, EGL_NO_CONTEXT, contextAttribs);
+	if (context_ == EGL_NO_CONTEXT) {
+		LOG(eGL, Error) << "eglContext returned EGL_NO_CONTEXT";
+		goto fail;
+	}
+
+	tid_ = Thread::currentId();
+
+	makeCurrent();
+
+	return 0;
+fail:
+
+	return -ENODEV;
+}
+
+/**
+ * \brief Clean up EGL resources
+ *
+ * Destroys the EGL sync object. Must be called from the same thread
+ * that created the EGL context.
+ */
+void eGL::cleanUp()
+{
+}
+
+/**
+ * \brief Make the EGL context current for the calling thread
+ *
+ * Binds the EGL context to the current thread, allowing OpenGL ES
+ * operations to be performed. Must be called from the thread that
+ * will perform rendering operations.
+ */
+void eGL::makeCurrent()
+{
+	ASSERT(tid_ == Thread::currentId());
+
+	if (eglMakeCurrent(display_, EGL_NO_SURFACE, EGL_NO_SURFACE, context_) != EGL_TRUE) {
+		LOG(eGL, Error) << "eglMakeCurrent fail";
+	}
+}
+
+/**
+ * \brief Activate a shader program for rendering
+ * \param[in] programId OpenGL program object ID
+ *
+ * Sets the specified program as the current rendering program. All
+ * subsequent draw calls will use this program's shaders.
+ */
+void eGL::useProgram(GLuint programId)
+{
+	ASSERT(tid_ == Thread::currentId());
+
+	glUseProgram(programId);
+}
+
+/**
+ * \brief Delete a shader program
+ * \param[in] programId OpenGL program object ID
+ *
+ * Deletes a shader program and frees associated resources. The program
+ * must not be currently in use.
+ */
+void eGL::deleteProgram(GLuint programId)
+{
+	ASSERT(tid_ == Thread::currentId());
+
+	glDeleteProgram(programId);
+}
+
+/**
+ * \brief Add a preprocessor definition to shader environment
+ * \param[in,out] shaderEnv Vector of shader environment strings
+ * \param[in] str Preprocessor definition string (e.g., "#define APPLY_RGB_PARAMETERS")
+ *
+ * Appends a preprocessor definition to the shader environment vector.
+ * These definitions are prepended to shader source code during compilation.
+ */
+void eGL::pushEnv(std::vector<std::string> &shaderEnv, const char *str)
+{
+	std::string addStr = str;
+
+	addStr.push_back('\n');
+	shaderEnv.push_back(std::move(addStr));
+}
+
+/**
+ * \brief Compile a vertex shader
+ * \param[out] shaderId OpenGL shader object ID
+ * \param[in] shaderData Pointer to shader source code
+ * \param[in] shaderDataLen Length of shader source in bytes
+ * \param[in] shaderEnv Span of preprocessor definitions to prepend
+ *
+ * Compiles a vertex shader from source code with optional preprocessor
+ * definitions. On compilation failure, logs the shader info log.
+ *
+ * \return 0 on success, or -EINVAL on compilation failure
+ */
+int eGL::compileVertexShader(GLuint &shaderId, const unsigned char *shaderData,
+			     unsigned int shaderDataLen,
+			     Span<const std::string> shaderEnv)
+{
+	return compileShader(GL_VERTEX_SHADER, shaderId, shaderData, shaderDataLen, shaderEnv);
+}
+
+/**
+ * \brief Compile a fragment shader
+ * \param[out] shaderId OpenGL shader object ID
+ * \param[in] shaderData Pointer to shader source code
+ * \param[in] shaderDataLen Length of shader source in bytes
+ * \param[in] shaderEnv Span of preprocessor definitions to prepend
+ *
+ * Compiles a fragment shader from source code with optional preprocessor
+ * definitions. On compilation failure, logs the shader info log.
+ *
+ * \return 0 on success, or -EINVAL on compilation failure
+ */
+int eGL::compileFragmentShader(GLuint &shaderId, const unsigned char *shaderData,
+			       unsigned int shaderDataLen,
+			       Span<const std::string> shaderEnv)
+{
+	return compileShader(GL_FRAGMENT_SHADER, shaderId, shaderData, shaderDataLen, shaderEnv);
+}
+
+/**
+ * \brief Compile a shader of specified type
+ * \param[in] shaderType GL_VERTEX_SHADER or GL_FRAGMENT_SHADER
+ * \param[out] shaderId OpenGL shader object ID
+ * \param[in] shaderData Pointer to shader source code
+ * \param[in] shaderDataLen Length of shader source in bytes
+ * \param[in] shaderEnv Span of preprocessor definitions to prepend
+ *
+ * Internal helper function for shader compilation. Prepends environment
+ * definitions to the shader source and compiles the shader.
+ *
+ * \return 0 on success, or -EINVAL on compilation failure
+ */
+int eGL::compileShader(int shaderType, GLuint &shaderId, const unsigned char *shaderData,
+		       unsigned int shaderDataLen,
+		       Span<const std::string> shaderEnv)
+{
+	GLint success;
+	size_t i;
+
+	ASSERT(tid_ == Thread::currentId());
+
+	auto count = 1 + shaderEnv.size();
+	auto shaderSourceData = std::make_unique<const GLchar *[]>(count);
+	auto shaderDataLengths = std::make_unique<GLint[]>(count);
+
+	// Prefix defines before main body of shader
+	for (i = 0; i < shaderEnv.size(); i++) {
+		shaderSourceData[i] = shaderEnv[i].c_str();
+		shaderDataLengths[i] = shaderEnv[i].length();
+	}
+
+	// Now the main body of the shader program
+	shaderSourceData[i] = reinterpret_cast<const GLchar *>(shaderData);
+	shaderDataLengths[i] = shaderDataLen;
+
+	// And create the shader
+	shaderId = glCreateShader(shaderType);
+	glShaderSource(shaderId, count, shaderSourceData.get(), shaderDataLengths.get());
+	glCompileShader(shaderId);
+
+	// Check status
+	glGetShaderiv(shaderId, GL_COMPILE_STATUS, &success);
+	if (success == GL_FALSE) {
+		GLint sizeLog = 0;
+
+		glGetShaderiv(shaderId, GL_INFO_LOG_LENGTH, &sizeLog);
+		auto infoLog = std::make_unique<GLchar[]>(sizeLog);
+
+		glGetShaderInfoLog(shaderId, sizeLog, &sizeLog, infoLog.get());
+		LOG(eGL, Error) << infoLog.get();
+	}
+
+	return (success == GL_TRUE) ? 0 : -EINVAL;
+}
+
+/**
+ * \brief Dump shader source code to the log
+ * \param[in] shaderId OpenGL shader object ID
+ *
+ * Retrieves and logs the complete source code of a compiled shader.
+ * Useful for debugging shader compilation issues.
+ */
+void eGL::dumpShaderSource(GLuint shaderId)
+{
+	GLint shaderLength = 0;
+
+	ASSERT(tid_ == Thread::currentId());
+
+	glGetShaderiv(shaderId, GL_SHADER_SOURCE_LENGTH, &shaderLength);
+
+	LOG(eGL, Debug) << "Shader length is " << shaderLength;
+
+	if (shaderLength > 0) {
+		auto shaderSource = std::make_unique<GLchar[]>(shaderLength);
+
+		glGetShaderSource(shaderId, shaderLength, &shaderLength, shaderSource.get());
+		if (shaderLength) {
+			LOG(eGL, Debug) << "Shader source = " << shaderSource.get();
+		}
+	}
+}
+
+/**
+ * \brief Link a shader program
+ * \param[out] programId OpenGL program object ID
+ * \param[in] fragmentshaderId Compiled fragment shader ID
+ * \param[in] vertexshaderId Compiled vertex shader ID
+ *
+ * Links vertex and fragment shaders into an executable shader program.
+ * On link failure, logs the program info log and deletes the program.
+ *
+ * \return 0 on success, or -ENODEV on link failure
+ */
+int eGL::linkProgram(GLuint &programId, GLuint vertexshaderId, GLuint fragmentshaderId)
+{
+	GLint success;
+	GLenum err;
+	int ret = -ENODEV;
+
+	ASSERT(tid_ == Thread::currentId());
+
+	programId = glCreateProgram();
+	if (!programId) {
+		LOG(eGL, Error) << "glGreateProgram error";
+		return ret;
+	}
+
+	utils::scope_exit programGuard([&] { glDeleteProgram(programId); });
+
+	glAttachShader(programId, vertexshaderId);
+	if ((err = glGetError()) != GL_NO_ERROR) {
+		LOG(eGL, Error) << "Attach compute vertex shader fail err=" << err;
+		return ret;
+	}
+
+	glAttachShader(programId, fragmentshaderId);
+	if ((err = glGetError()) != GL_NO_ERROR) {
+		LOG(eGL, Error) << "Attach compute fragment shader fail err=" << err;
+		return ret;
+	}
+
+	glLinkProgram(programId);
+	if ((err = glGetError()) != GL_NO_ERROR) {
+		LOG(eGL, Error) << "Link program fail err=" << err;
+		return ret;
+	}
+
+	glDetachShader(programId, fragmentshaderId);
+	glDetachShader(programId, vertexshaderId);
+
+	// Check status
+	glGetProgramiv(programId, GL_LINK_STATUS, &success);
+	if (success == GL_FALSE) {
+		GLint sizeLog = 0;
+
+		glGetProgramiv(programId, GL_INFO_LOG_LENGTH, &sizeLog);
+		auto infoLog = std::make_unique<GLchar[]>(sizeLog);
+
+		glGetProgramInfoLog(programId, sizeLog, &sizeLog, infoLog.get());
+		LOG(eGL, Error) << infoLog.get();
+
+		return ret;
+	}
+
+	programGuard.release();
+	return 0;
+}
+} /* namespace libcamera */
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index cb7863852..6f952bd98 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -79,6 +79,27 @@  if libgbm.found() and gbm_works
     ])
 endif
 
+mesa_works = cc.check_header('EGL/egl.h', required: false)
+libegl = dependency('egl', required : false)
+libglesv2 = dependency('glesv2', required : false)
+
+if libegl.found()
+    config_h.set('HAVE_LIBEGL', 1)
+endif
+
+if libglesv2.found()
+    config_h.set('HAVE_GLESV2', 1)
+endif
+
+if mesa_works and gbm_works
+    libcamera_internal_sources += files([
+        'egl.cpp',
+    ])
+    gles_headless_enabled = true
+else
+    gles_headless_enabled = false
+endif
+
 subdir('base')
 subdir('converter')
 subdir('ipa')
@@ -187,7 +208,9 @@  libcamera_deps += [
     libcamera_base_private,
     libcrypto,
     libdl,
+    libegl,
     libgbm,
+    libglesv2,
     liblttng,
     libudev,
     libyaml,