WebGLRenderingContext.blendEquation()

The WebGLRenderingContext.blendEquation() method of the WebGL API is used to set both the RGB blend equation and alpha blend equation to a single equation.

The blend equation determines how a new pixel is combined with a pixel already in the WebGLFramebuffer.

Syntax

void gl.blendEquation(mode);

Parameters

mode
A GLenum specifying how source and destination colors are combined. Must be either:
  • gl.FUNC_ADD: source + destination,
  • gl.FUNC_SUBTRACT: source - destination,
  • gl.FUNC_REVERSE_SUBTRACT: destination - source
  • When using the EXT_blend_minmax extension:
    • ext.MIN_EXT: Minimum of source and destination,
    • ext.MAX_EXT: Maximum of source and destination.
  • When using a WebGL 2 context, the following values are available additionally:
    • gl.MIN: Minimum of source and destination,
    • gl.MAX: Maximum of source and destination.

default value: gl.FUNC_ADD

Exception

If mode is not one of the three possible values, a gl.INVALID_ENUM error is thrown.

Return value

None.

Examples

To set the blend equation, use:

gl.blendEquation(gl.FUNC_ADD);
gl.blendEquation(gl.FUNC_SUBTRACT);
gl.blendEquation(gl.FUNC_REVERSE_SUBTRACT);

To get the blend equations, query the BLEND_EQUATION, BLEND_EQUATION_RGB and BLEND_EQUATION_ALPHA constants which return gl.FUNC_ADD, gl.FUNC_SUBTRACT, gl.FUNC_REVERSE_SUBTRACT, or if the EXT_blend_minmax is enabled: ext.MIN_EXT or ext.MAX_EXT.

gl.getParameter(gl.BLEND_EQUATION_RGB) === gl.FUNC_ADD;
// true

gl.getParameter(gl.BLEND_EQUATION_ALPHA) === gl.FUNC_ADD; 
// true

Specifications

Specification Status Comment
WebGL 1.0
The definition of 'blendEquation' in that specification.		 Recommendation Initial definition for WebGL.
OpenGL ES 2.0
The definition of 'glBlendEquation' in that specification.		 Standard Man page of the OpenGL ES 2.0 API.
OpenGL ES 3.0
The definition of 'glBlendEquation' in that specification.		 Standard Man page of the OpenGL ES 3.0 API.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
blendEquationChrome Full support 9Edge Full support 12Firefox Full support 4IE Full support 11Opera Full support 12Safari Full support 5.1WebView Android Full support YesChrome Android Full support 25Firefox Android Full support YesOpera Android Full support 12Safari iOS Full support 8Samsung Internet Android Full support 1.5
WebGL2Chrome Full support 56Edge Full support 79Firefox Full support 51IE No support NoOpera Full support 43Safari No support NoWebView Android Full support 58Chrome Android Full support 58Firefox Android Full support 51Opera Android Full support 43Safari iOS No support NoSamsung Internet Android Full support 7.0

Legend

Full support  
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No support  
No support

See also

Related Topics
  1. WebGL API
  2. WebGLRenderingContext
  3. Properties
    1. canvas
    2. drawingBufferHeight
    3. drawingBufferWidth
  4. Methods
    1. activeTexture()
    2. attachShader()
    3. bindAttribLocation()
    4. bindBuffer()
    5. bindFramebuffer()
    6. bindRenderbuffer()
    7. bindTexture()
    8. blendColor()
    9. blendEquation()
    10. blendEquationSeparate()
    11. blendFunc()
    12. blendFuncSeparate()
    13. bufferData()
    14. bufferSubData()
    15. checkFramebufferStatus()
    16. clear()
    17. clearColor()
    18. clearDepth()
    19. clearStencil()
    20. colorMask()
    21. commit()
    22. compileShader()
    23. compressedTexImage[23]D()
    24. compressedTexSubImage2D()
    25. copyTexImage2D()
    26. copyTexSubImage2D()
    27. createBuffer()
    28. createFramebuffer()
    29. createProgram()
    30. createRenderbuffer()
    31. createShader()
    32. createTexture()
    33. cullFace()
    34. deleteBuffer()
    35. deleteFramebuffer()
    36. deleteProgram()
    37. deleteRenderbuffer()
    38. deleteShader()
    39. deleteTexture()
    40. depthFunc()
    41. depthMask()
    42. depthRange()
    43. detachShader()
    44. disable()
    45. disableVertexAttribArray()
    46. drawArrays()
    47. drawElements()
    48. enable()
    49. enableVertexAttribArray()
    50. finish()
    51. flush()
    52. framebufferRenderbuffer()
    53. framebufferTexture2D()
    54. frontFace()
    55. generateMipmap()
    56. getActiveAttrib()
    57. getActiveUniform()
    58. getAttachedShaders()
    59. getAttribLocation()
    60. getBufferParameter()
    61. getContextAttributes()
    62. getError()
    63. getExtension()
    64. getFramebufferAttachmentParameter()
    65. getParameter()
    66. getProgramInfoLog()
    67. getProgramParameter()
    68. getRenderbufferParameter()
    69. getShaderInfoLog()
    70. getShaderParameter()
    71. getShaderPrecisionFormat()
    72. getShaderSource()
    73. getSupportedExtensions()
    74. getTexParameter()
    75. getUniform()
    76. getUniformLocation()
    77. getVertexAttrib()
    78. getVertexAttribOffset()
    79. hint()
    80. isBuffer()
    81. isContextLost()
    82. isEnabled()
    83. isFramebuffer()
    84. isProgram()
    85. isRenderbuffer()
    86. isShader()
    87. isTexture()
    88. lineWidth()
    89. linkProgram()
    90. pixelStorei()
    91. polygonOffset()
    92. readPixels()
    93. renderbufferStorage()
    94. sampleCoverage()
    95. scissor()
    96. shaderSource()
    97. stencilFunc()
    98. stencilFuncSeparate()
    99. stencilMask()
    100. stencilMaskSeparate()
    101. stencilOp()
    102. stencilOpSeparate()
    103. texImage2D()
    104. texParameter[fi]()
    105. texSubImage2D()
    106. uniform[1234][fi][v]()
    107. uniformMatrix[234]fv()
    108. useProgram()
    109. validateProgram()
    110. vertexAttrib[1234]f[v]()
    111. vertexAttribPointer()
    112. viewport()
  5. Related pages for WebGL
    1. ANGLE_instanced_arrays
    2. EXT_blend_minmax
    3. EXT_color_buffer_half_float
    4. EXT_disjoint_timer_query
    5. EXT_frag_depth
    6. EXT_sRGB
    7. EXT_shader_texture_lod
    8. EXT_texture_filter_anisotropic
    9. OES_element_index_uint
    10. OES_standard_derivatives
    11. OES_texture_float
    12. OES_texture_float_linear
    13. OES_texture_half_float
    14. OES_texture_half_float_linear
    15. OES_vertex_array_object
    16. WEBGL_color_buffer_float
    17. WEBGL_compressed_texture_atc
    18. WEBGL_compressed_texture_etc1
    19. WEBGL_compressed_texture_pvrtc
    20. WEBGL_compressed_texture_s3tc
    21. WEBGL_compressed_texture_s3tc_srgb
    22. WEBGL_debug_renderer_info
    23. WEBGL_debug_shaders
    24. WEBGL_depth_texture
    25. WEBGL_draw_buffers
    26. WEBGL_lose_context
    27. WebGL2RenderingContext
    28. WebGLActiveInfo
    29. WebGLBuffer
    30. WebGLContextEvent
    31. WebGLFramebuffer
    32. WebGLObject
    33. WebGLProgram
    34. WebGLQuery
    35. WebGLRenderbuffer
    36. WebGLSampler
    37. WebGLShader
    38. WebGLShaderPrecisionFormat
    39. WebGLSync
    40. WebGLTexture
    41. WebGLTransformFeedback
    42. WebGLUniformLocation
    43. WebGLVertexArrayObject