WebGLRenderingContext

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

The WebGLRenderingContext class provides the WebGL 1.0 rendering context (OpenGL ES 2.0). It is obtained from an HTMLCanvasElement or OffscreenCanvas via getContext("webgl"). SpawnDev.SpawnJS provides the full WebGL 1.0 API surface through WebGLRenderingContextBase, which contains all methods shared between WebGL 1.0 and 2.0. All WebGL constants are accessible via the static WebGLConstants class.

Constructors

Signature	Description
`WebGLRenderingContext(SpawnJSObjectReference _ref)`	Deserialization constructor.

Key Methods (from WebGLRenderingContextBase)

Shader Methods

Method	Return Type	Description
`CreateShader(int type)`	`WebGLShader`	Creates a shader. Use `WebGLConstants.VERTEX_SHADER` or `FRAGMENT_SHADER`.
`ShaderSource(WebGLShader shader, string source)`	`void`	Sets the GLSL source code for a shader.
`CompileShader(WebGLShader shader)`	`void`	Compiles the shader source.
`GetShaderParameter(WebGLShader shader, int pname)`	`T`	Gets shader compile status. Use `WebGLConstants.COMPILE_STATUS`.
`GetShaderInfoLog(WebGLShader shader)`	`string?`	Returns the shader compilation log (error messages).
`DeleteShader(WebGLShader shader)`	`void`	Deletes a shader object.

Program Methods

Method	Return Type	Description
`CreateProgram()`	`WebGLProgram`	Creates a shader program.
`AttachShader(WebGLProgram program, WebGLShader shader)`	`void`	Attaches a shader to a program.
`LinkProgram(WebGLProgram program)`	`void`	Links the program (after attaching both shaders).
`UseProgram(WebGLProgram? program)`	`void`	Sets the active shader program.
`GetProgramParameter<T>(WebGLProgram program, int pname)`	`T`	Gets link status. Use `WebGLConstants.LINK_STATUS`.
`GetProgramInfoLog(WebGLProgram program)`	`string?`	Returns the program link log.
`DeleteProgram(WebGLProgram program)`	`void`	Deletes a program.

Buffer Methods

Method	Return Type	Description
`CreateBuffer()`	`WebGLBuffer`	Creates a buffer object.
`BindBuffer(int target, WebGLBuffer? buffer)`	`void`	Binds a buffer. Target: `ARRAY_BUFFER`, `ELEMENT_ARRAY_BUFFER`.
`BufferData(int target, TypedArray data, int usage)`	`void`	Uploads data to the bound buffer. Usage: `STATIC_DRAW`, `DYNAMIC_DRAW`, `STREAM_DRAW`.
`BufferData(int target, long size, int usage)`	`void`	Allocates buffer storage.
`BufferData(int target, ArrayBuffer data, int usage)`	`void`	Uploads ArrayBuffer data.
`BufferSubData(int target, long offset, TypedArray data)`	`void`	Updates a portion of the buffer.
`DeleteBuffer(WebGLBuffer buffer)`	`void`	Deletes a buffer.

Texture Methods

Method	Return Type	Description
`CreateTexture()`	`WebGLTexture`	Creates a texture object.
`BindTexture(int target, WebGLTexture? texture)`	`void`	Binds a texture. Target: `TEXTURE_2D`, `TEXTURE_CUBE_MAP`.
`TexImage2D(int target, int level, int internalformat, int width, int height, int border, int format, int type, TypedArray? pixels)`	`void`	Specifies a 2D texture image.
`TexParameteri(int target, int pname, int param)`	`void`	Sets texture parameters (filtering, wrapping).
`GenerateMipmap(int target)`	`void`	Generates mipmaps for the bound texture.
`ActiveTexture(int texture)`	`void`	Selects the active texture unit.
`DeleteTexture(WebGLTexture texture)`	`void`	Deletes a texture.

Vertex Attribute Methods

Method	Return Type	Description
`GetAttribLocation(WebGLProgram program, string name)`	`int`	Returns the location of an attribute variable.
`VertexAttribPointer(int index, int size, int type, bool normalized, int stride, long offset)`	`void`	Specifies the layout of vertex attribute data.
`EnableVertexAttribArray(int index)`	`void`	Enables a vertex attribute array.
`DisableVertexAttribArray(int index)`	`void`	Disables a vertex attribute array.

Uniform Methods

Method	Return Type	Description
`GetUniformLocation(WebGLProgram program, string name)`	`WebGLUniformLocation`	Returns the location of a uniform variable.
`Uniform1f(WebGLUniformLocation location, float v0)`	`void`	Sets a float uniform.
`Uniform1i(WebGLUniformLocation location, int v0)`	`void`	Sets an integer uniform.
`Uniform2f(WebGLUniformLocation loc, float v0, float v1)`	`void`	Sets a vec2 uniform.
`Uniform3f(WebGLUniformLocation loc, float v0, float v1, float v2)`	`void`	Sets a vec3 uniform.
`Uniform4f(WebGLUniformLocation loc, float v0, float v1, float v2, float v3)`	`void`	Sets a vec4 uniform.
`UniformMatrix4fv(WebGLUniformLocation location, bool transpose, Float32Array value)`	`void`	Sets a 4x4 matrix uniform.

Drawing Methods

Method	Return Type	Description
`DrawArrays(int mode, int first, int count)`	`void`	Draws primitives from array data. Mode: `TRIANGLES`, `LINES`, `POINTS`, etc.
`DrawElements(int mode, int count, int type, long offset)`	`void`	Draws indexed primitives.

State Methods

Method	Return Type	Description
`Clear(int mask)`	`void`	Clears buffers. Mask: `COLOR_BUFFER_BIT`, `DEPTH_BUFFER_BIT`, `STENCIL_BUFFER_BIT`.
`ClearColor(float red, float green, float blue, float alpha)`	`void`	Sets the clear color.
`ClearDepth(float depth)`	`void`	Sets the clear depth value.
`Viewport(int x, int y, int width, int height)`	`void`	Sets the viewport.
`Enable(int cap)`	`void`	Enables a capability (e.g., `DEPTH_TEST`, `BLEND`, `CULL_FACE`).
`Disable(int cap)`	`void`	Disables a capability.
`BlendFunc(int sfactor, int dfactor)`	`void`	Sets the blending function.
`DepthFunc(int func)`	`void`	Sets the depth comparison function.
`Scissor(int x, int y, int width, int height)`	`void`	Sets the scissor rectangle.

Framebuffer Methods

Method	Return Type	Description
`CreateFramebuffer()`	`WebGLFramebuffer`	Creates a framebuffer.
`BindFramebuffer(int target, WebGLFramebuffer? framebuffer)`	`void`	Binds a framebuffer.
`FramebufferTexture2D(int target, int attachment, int textarget, WebGLTexture texture, int level)`	`void`	Attaches a texture to a framebuffer.
`DeleteFramebuffer(WebGLFramebuffer framebuffer)`	`void`	Deletes a framebuffer.

Other Methods

Method	Return Type	Description
`Flush()`	`void`	Flushes the GL command queue.
`Finish()`	`void`	Blocks until all GL commands are complete.
`GetError()`	`int`	Returns the current error code.
`ReadPixels(int x, int y, int width, int height, int format, int type, TypedArray pixels)`	`void`	Reads pixel data from the framebuffer.
`GetExtension(string name)`	`SpawnJSObject?`	Returns a WebGL extension, or `null`.
`GetParameter<T>(int pname)`	`T`	Returns a GL parameter value.

WebGLConstants

All WebGL constants are available as static fields on WebGLConstants:

WebGLConstants.VERTEX_SHADER         // 35633
WebGLConstants.FRAGMENT_SHADER       // 35632
WebGLConstants.ARRAY_BUFFER          // 34962
WebGLConstants.ELEMENT_ARRAY_BUFFER  // 34963
WebGLConstants.STATIC_DRAW           // 35044
WebGLConstants.TRIANGLES             // 4
WebGLConstants.TEXTURE_2D            // 3553
WebGLConstants.COLOR_BUFFER_BIT      // 16384
WebGLConstants.DEPTH_BUFFER_BIT      // 256
// ... and many more

Example

// Get WebGL context from an OffscreenCanvas
using var canvas = new OffscreenCanvas(800, 600);
using var gl = canvas.GetWebGLContext();

// Set clear color and clear
gl.ClearColor(0.0f, 0.0f, 0.0f, 1.0f);
gl.Clear(WebGLConstants.COLOR_BUFFER_BIT);

// Create and compile vertex shader
using var vertShader = gl.CreateShader(WebGLConstants.VERTEX_SHADER);
gl.ShaderSource(vertShader, @"
    attribute vec4 aPosition;
    void main() {
        gl_Position = aPosition;
    }
");
gl.CompileShader(vertShader);

// Create and compile fragment shader
using var fragShader = gl.CreateShader(WebGLConstants.FRAGMENT_SHADER);
gl.ShaderSource(fragShader, @"
    precision mediump float;
    void main() {
        gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
    }
");
gl.CompileShader(fragShader);

// Create program
using var program = gl.CreateProgram();
gl.AttachShader(program, vertShader);
gl.AttachShader(program, fragShader);
gl.LinkProgram(program);
gl.UseProgram(program);

// Create vertex buffer
float[] vertices = { 0.0f, 0.5f, -0.5f, -0.5f, 0.5f, -0.5f };
using var vertexArray = new Float32Array(vertices);
using var buffer = gl.CreateBuffer();
gl.BindBuffer(WebGLConstants.ARRAY_BUFFER, buffer);
gl.BufferData(WebGLConstants.ARRAY_BUFFER, vertexArray, WebGLConstants.STATIC_DRAW);

// Set up vertex attribute
int posLocation = gl.GetAttribLocation(program, "aPosition");
gl.VertexAttribPointer(posLocation, 2, WebGLConstants.FLOAT, false, 0, 0);
gl.EnableVertexAttribArray(posLocation);

// Draw
gl.Viewport(0, 0, 800, 600);
gl.DrawArrays(WebGLConstants.TRIANGLES, 0, 3);

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WebGLRenderingContext

Constructors

Key Methods (from WebGLRenderingContextBase)

Shader Methods

Program Methods

Buffer Methods

Texture Methods

Vertex Attribute Methods

Uniform Methods

Drawing Methods

State Methods

Framebuffer Methods

Other Methods

WebGLConstants

Example

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WebGLRenderingContext

Constructors

Key Methods (from WebGLRenderingContextBase)

Shader Methods

Program Methods

Buffer Methods

Texture Methods

Vertex Attribute Methods

Uniform Methods

Drawing Methods

State Methods

Framebuffer Methods

Other Methods

WebGLConstants

Example