// newFBO will generate a new Frame Buffer Object for use with the canvas
func newFBO(texture gl.Texture) (gl.Framebuffer, uint32) {
// get currently bound fbo to reset to it later
current_fbo := gl.GetBoundFramebuffer()
framebuffer := gl.CreateFramebuffer()
gl.BindFramebuffer(gl.FRAMEBUFFER, framebuffer)
if texture.Valid() {
gl.FramebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0)
// Initialize the texture to transparent black.
gl.ClearColor(0.0, 0.0, 0.0, 0.0)
gl.Clear(gl.COLOR_BUFFER_BIT)
}
status := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
// unbind framebuffer
gl.BindFramebuffer(gl.FRAMEBUFFER, current_fbo)
return framebuffer, uint32(status)
}
// InitContext will initiate the opengl context with a viewport in the size of
// w x h. This is generally called from the game loop and wont generally need to
// be called unless you are rolling your own game loop.
func InitContext(w, h int32) {
if gl_state.initialized {
return
}
// Okay, setup OpenGL.
gl.ContextWatcher.OnMakeCurrent(nil)
//Get system info
opengl_version = gl.GetString(gl.VERSION)
opengl_vendor = gl.GetString(gl.VENDOR)
gl_state.defaultFBO = gl.GetBoundFramebuffer()
gl.GetIntegerv(gl.VIEWPORT, gl_state.viewport)
// And the current scissor - but we need to compensate for GL scissors
// starting at the bottom left instead of top left.
gl.GetIntegerv(gl.SCISSOR_BOX, states.back().scissorBox)
states.back().scissorBox[1] = gl_state.viewport[3] - (states.back().scissorBox[1] + states.back().scissorBox[3])
initMaxValues() //check shim code
glcolor := []float32{1.0, 1.0, 1.0, 1.0}
gl.VertexAttrib4fv(attrib_color, glcolor)
gl.VertexAttrib4fv(attrib_constantcolor, glcolor)
useVertexAttribArrays(0)
// Enable blending
gl.Enable(gl.BLEND)
SetBlendMode(BLENDMODE_ALPHA)
// Auto-generated mipmaps should be the best quality possible
gl.Hint(gl.GENERATE_MIPMAP_HINT, gl.NICEST)
// Make sure antialiasing works when set elsewhere
enableMultisample() //check shim code
// Set pixel row alignment
gl.PixelStorei(gl.UNPACK_ALIGNMENT, 1)
//default matricies
gl_state.projectionStack = matstack.NewMatStack()
gl_state.viewStack = matstack.NewMatStack() //stacks are initialized with ident matricies on top
SetViewportSize(w, h)
SetBackgroundColor(0, 0, 0, 255)
gl_state.boundTextures = make([]gl.Texture, maxTextureUnits)
curgltextureunit := gl.GetInteger(gl.ACTIVE_TEXTURE)
gl_state.curTextureUnit = int(curgltextureunit - gl.TEXTURE0)
// Retrieve currently bound textures for each texture unit.
for i := 0; i < len(gl_state.boundTextures); i++ {
gl.ActiveTexture(gl.Enum(gl.TEXTURE0 + uint32(i)))
gl_state.boundTextures[i] = gl.Texture{Value: uint32(gl.GetInteger(gl.TEXTURE_BINDING_2D))}
}
gl.ActiveTexture(gl.Enum(curgltextureunit))
createDefaultTexture()
setTextureUnit(0)
// We always need a default shader.
defaultShader = NewShader()
gl_state.initialized = true
loadAllVolatile()
//have to set this after loadallvolatile() so we are sure the default shader is loaded
SetShader(nil)
}