Fix WebGL2 getParameter() returning undefined for state and pixel store parameters

[Copilot]

30 WebGL2 parameters were missing from the getParameter() switch statement, causing them to return undefined instead of their OpenGL state values. This breaks conformance tests and application logic that queries pixel store settings, draw buffer bindings, or capability states.

Changes

Added to WebGLBooleanParameterName enum (3 parameters):

• SAMPLE_ALPHA_TO_COVERAGE, SAMPLE_COVERAGE - capability states
• RASTERIZER_DISCARD - WebGL2 capability state

Added to WebGL2IntegerParameterName enum (27 parameters):

• Pixel store: PACK_ROW_LENGTH, PACK_SKIP_PIXELS, PACK_SKIP_ROWS, UNPACK_ROW_LENGTH, UNPACK_IMAGE_HEIGHT, UNPACK_SKIP_PIXELS, UNPACK_SKIP_ROWS, UNPACK_SKIP_IMAGES
• State: FRAGMENT_SHADER_DERIVATIVE_HINT, READ_BUFFER, DRAW_BUFFER0 through DRAW_BUFFER15, UNIFORM_BUFFER_OFFSET_ALIGNMENT

Updated switch cases in GetParameter():

• Added new boolean parameters to GLboolean case
• Added new integer parameters to WebGL2 integer case

Example

// Before: returns undefined
const rowLength = gl.getParameter(gl.PACK_ROW_LENGTH);

// After: returns actual OpenGL state value (e.g., 0 for default)
const rowLength = gl.getParameter(gl.PACK_ROW_LENGTH); // 0

// Boolean states now work
const rasterizer = gl.getParameter(gl.RASTERIZER_DISCARD); // false

All constants already existed in webgl_constants.hpp—they were simply not wired through the parameter query path.

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Original prompt

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This section details on the original issue you should resolve

<issue_title>WebGL2 context.getParameter returns undefined for state and numeric parameters</issue_title>
<issue_description>### Problem
Calling context.getParameter() for several numeric or stateful parameters (not direct object bindings) such as:

• FRAGMENT_SHADER_DERIVATIVE_HINT
• PACK_ROW_LENGTH
• PACK_SKIP_PIXELS
• PACK_SKIP_ROWS
• UNPACK_IMAGE_HEIGHT
• UNPACK_ROW_LENGTH
• UNPACK_SKIP_IMAGES
• UNPACK_SKIP_PIXELS
• UNPACK_SKIP_ROWS
• RASTERIZER_DISCARD
• SAMPLE_ALPHA_TO_COVERAGE
• SAMPLE_COVERAGE
• READ_BUFFER
• DRAW_BUFFER0
• MAX_3D_TEXTURE_SIZE
• MAX_SERVER_WAIT_TIMEOUT
• MIN_PROGRAM_TEXEL_OFFSET
• UNIFORM_BUFFER_OFFSET_ALIGNMENT

...returns undefined instead of a valid value (should be integer, float, or boolean according to spec). Some should have a default value (e.g., 0 for PACK_ROW_LENGTH), or a specific constant (e.g., 1029 for DRAW_BUFFER0).

Expected Behavior

All WebGL2 state and capability parameters queried via getParameter() should always return a correct spec-compliant value, never undefined. This applies to API conformance and ensures portability.

Impact

• Causes conformance tests to fail
• Prevents expected application logic (e.g., typed array allocations, feature detection)

References

• WebGL2 getParameter Spec
• Chromium implementation example

Suggested Actions

• Audit numeric/boolean parameters in WebGL2 context.getParameter()
• Implement default/fallback values according to specification
• Add/extend regression tests to cover these cases

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Category: WebGL2 parameter state compliance</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes WebGL2 context.getParameter returns undefined for state and numeric parameters #420

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