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WebGL2RenderingContext

Namespace: SpawnDev.SpawnJS.JSObjects
Inheritance: SpawnJSObject -> WebGLRenderingContextBase -> WebGL2RenderingContextBase -> WebGL2RenderingContext
MDN Reference: WebGL2RenderingContext

The WebGL2RenderingContext class provides the WebGL 2.0 rendering context (OpenGL ES 3.0). It inherits all WebGL 1.0 functionality from WebGLRenderingContextBase and adds WebGL 2.0 features through WebGL2RenderingContextBase, including vertex array objects (VAOs), transform feedback, instanced drawing, 3D textures, query objects, sync objects, samplers, and uniform buffer objects. Obtained via getContext("webgl2") on a canvas or OffscreenCanvas.GetWebGL2Context().

Constructors

Signature Description
WebGL2RenderingContext(SpawnJSObjectReference _ref) Deserialization constructor.

Additional Methods (WebGL 2.0 - from WebGL2RenderingContextBase)

All WebGL 1.0 methods from WebGLRenderingContext are available. The following are WebGL 2.0 additions:

Vertex Array Objects (VAOs)

Method Return Type Description
CreateVertexArray() WebGLVertexArrayObject Creates a new VAO.
BindVertexArray(WebGLVertexArrayObject? vao) void Binds a VAO. Pass null to unbind.
DeleteVertexArray(WebGLVertexArrayObject vao) void Deletes a VAO.
IsVertexArray(WebGLVertexArrayObject vao) bool Tests if an object is a valid VAO.

Query Objects

Method Return Type Description
CreateQuery() WebGLQuery Creates a query object.
BeginQuery(int target, WebGLQuery query) void Begins an asynchronous query (e.g., ANY_SAMPLES_PASSED).
EndQuery(int target) void Ends the active query on the target.
GetQueryParameter<T>(WebGLQuery query, int pname) T Gets a query result (e.g., QUERY_RESULT).
DeleteQuery(WebGLQuery query) void Deletes a query.

Sync Objects

Method Return Type Description
FenceSync(int condition, int flags) WebGLSync Creates a fence sync object.
ClientWaitSync(WebGLSync sync, int flags, long timeout) int Blocks until the sync condition is signaled or timeout. Returns ALREADY_SIGNALED, TIMEOUT_EXPIRED, CONDITION_SATISFIED, or WAIT_FAILED.
DeleteSync(WebGLSync sync) void Deletes a sync object.
GetSyncParameter<T>(WebGLSync sync, int pname) T Gets a sync parameter.
WaitSync(WebGLSync sync, int flags, long timeout) void Server-side wait on a sync object.
IsSync(WebGLSync sync) bool Tests if an object is a valid sync.

Texture Storage

Method Return Type Description
TexStorage2D(int target, int levels, int internalformat, int width, int height) void Allocates immutable 2D texture storage.
TexStorage3D(int target, int levels, int internalformat, int width, int height, int depth) void Allocates immutable 3D texture storage.
TexImage3D(...) void Specifies a 3D texture image.
TexSubImage3D(...) void Updates a sub-region of a 3D texture.
CompressedTexSubImage3D(...) void Specifies a compressed 3D texture sub-image.

Instanced Drawing

Method Return Type Description
DrawArraysInstanced(int mode, int first, int count, int instanceCount) void Draws instanced primitives from array data.
DrawElementsInstanced(int mode, int count, int type, long offset, int instanceCount) void Draws instanced indexed primitives.
VertexAttribDivisor(int index, int divisor) void Sets the divisor for instanced attributes.
DrawRangeElements(int mode, int start, int end, int count, int type, long offset) void Draws elements within a range.

Transform Feedback

Method Return Type Description
CreateTransformFeedback() WebGLTransformFeedback Creates a transform feedback object.
BindTransformFeedback(int target, WebGLTransformFeedback? tf) void Binds a transform feedback object.
BeginTransformFeedback(int primitiveMode) void Begins transform feedback recording.
EndTransformFeedback() void Ends transform feedback recording.
TransformFeedbackVaryings(WebGLProgram program, string[] varyings, int bufferMode) void Specifies output varyings for transform feedback.
DeleteTransformFeedback(WebGLTransformFeedback tf) void Deletes a transform feedback object.

Samplers

Method Return Type Description
CreateSampler() WebGLSampler Creates a sampler object.
BindSampler(int unit, WebGLSampler? sampler) void Binds a sampler to a texture unit.
SamplerParameteri(WebGLSampler sampler, int pname, int param) void Sets an integer sampler parameter.
SamplerParameterf(WebGLSampler sampler, int pname, float param) void Sets a float sampler parameter.
DeleteSampler(WebGLSampler sampler) void Deletes a sampler.

Uniform Buffer Objects

Method Return Type Description
GetUniformBlockIndex(WebGLProgram program, string uniformBlockName) int Returns the index of a uniform block.
UniformBlockBinding(WebGLProgram program, int uniformBlockIndex, int uniformBlockBinding) void Assigns a binding point to a uniform block.
BindBufferBase(int target, int index, WebGLBuffer? buffer) void Binds a buffer to an indexed target.
BindBufferRange(int target, int index, WebGLBuffer buffer, long offset, long size) void Binds a buffer range to an indexed target.

Other WebGL 2.0 Methods

Method Return Type Description
ReadBuffer(int src) void Selects a color buffer for reading pixels.
BlitFramebuffer(...) void Copies a region between framebuffers.
InvalidateFramebuffer(int target, int[] attachments) void Invalidates framebuffer attachments.
GetBufferSubData(int target, long srcByteOffset, TypedArray dstData) void Reads buffer data back to CPU.
CopyBufferSubData(int readTarget, int writeTarget, long readOffset, long writeOffset, long size) void Copies data between buffers.

Example

// Get WebGL2 context
using var canvas = new OffscreenCanvas(800, 600);
using var gl = canvas.GetWebGL2Context();

// Use Vertex Array Objects (VAO) - WebGL 2.0 feature
using var vao = gl.CreateVertexArray();
gl.BindVertexArray(vao);

// Set up vertex buffer
float[] vertices = { -0.5f, -0.5f, 0.5f, -0.5f, 0.0f, 0.5f };
using var vbo = gl.CreateBuffer();
gl.BindBuffer(WebGLConstants.ARRAY_BUFFER, vbo);
using var vertData = new Float32Array(vertices);
gl.BufferData(WebGLConstants.ARRAY_BUFFER, vertData, WebGLConstants.STATIC_DRAW);
gl.VertexAttribPointer(0, 2, WebGLConstants.FLOAT, false, 0, 0);
gl.EnableVertexAttribArray(0);

// Instanced drawing - render 100 instances
gl.VertexAttribDivisor(1, 1);  // Per-instance attribute
gl.DrawArraysInstanced(WebGLConstants.TRIANGLES, 0, 3, 100);

// Sync objects for GPU-CPU synchronization
using var sync = gl.FenceSync(WebGLConstants.SYNC_GPU_COMMANDS_COMPLETE, 0);
gl.Flush();
int status = gl.ClientWaitSync(sync, WebGLConstants.SYNC_FLUSH_COMMANDS_BIT, 1000000);

// Texture storage (immutable allocation)
using var tex = gl.CreateTexture();
gl.BindTexture(WebGLConstants.TEXTURE_2D, tex);
gl.TexStorage2D(WebGLConstants.TEXTURE_2D, 1, WebGLConstants.RGBA8, 512, 512);