OpenGL Blend

glBlendFunc — specify pixel arithmetic

• void glBlendFunc(GLenum sfactor, GLenum dfactor);
• void glBlendFunci(GLuint buf, GLenum sfactor, GLenum dfactor);

Parameters

1. buf
• For glBlendFunci, specifies the index of the draw buffer for which to set the blend function.
2. sfactor
• Specifies how the red, green, blue, and alpha source blending factors are computed. The initial value is GL_ONE.
3. dfactor
• Specifies how the red, green, blue, and alpha destination blending factors are computed. The initial value is GL_ZERO. The following symbolic constants are accepted: 
• GL_ZERO, GL_ONE
• GL_SRC_COLOR
• GL_ONE_MINUS_SRC_COLOR
• GL_DST_COLOR
• GL_ONE_MINUS_DST_COLOR
• GL_SRC_ALPHA
• GL_ONE_MINUS_SRC_ALPHA
• GL_DST_ALPHA
• GL_ONE_MINUS_DST_ALPHA
• GL_CONSTANT_COLOR
• GL_ONE_MINUS_CONSTANT_COLOR
• GL_CONSTANT_ALPHA
• GL_ONE_MINUS_CONSTANT_ALPHA