// generateMipmaps will generate mipmaps for the gl texture
func (texture *Texture) generateMipmaps() {
// The GL_GENERATE_MIPMAP texparameter is set in loadVolatile if we don't
// have support for glGenerateMipmap.
if texture.mipmaps {
// Driver bug: http://www.opengl.org/wiki/Common_Mistakes#Automatic_mipmap_generation
if runtime.GOOS == "windows" || runtime.GOOS == "linux" {
gl.Enable(gl.TEXTURE_2D)
}
gl.GenerateMipmap(gl.TEXTURE_2D)
}
}
// StencilExt operates like stencil but with access to change the stencil action,
// value, and keepvalues.
//
// action: How to modify any stencil values of pixels that are touched by what's
// drawn in the stencil function.
//
// value: The new stencil value to use for pixels if the "replace" stencil action
// is used. Has no effect with other stencil actions. Must be between 0 and 255.
//
// keepvalues: True to preserve old stencil values of pixels, false to re-set
// every pixel's stencil value to 0 before executing the stencil function. Clear
// will also re-set all stencil values.
func StencilExt(stencil_func func(), action StencilAction, value int32, keepvalues bool) {
gl_state.writingToStencil = true
if !keepvalues {
gl.Clear(gl.STENCIL_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
}
if gl_state.currentCanvas != nil {
gl_state.currentCanvas.checkCreateStencil()
}
gl.Enable(gl.STENCIL_TEST)
gl.ColorMask(false, false, false, false)
gl.StencilFunc(gl.ALWAYS, int(value), 0xFF)
gl.StencilOp(gl.KEEP, gl.KEEP, gl.Enum(action))
stencil_func()
gl_state.writingToStencil = false
SetColorMask(states.back().colorMask)
SetStencilTest(states.back().stencilCompare, states.back().stencilTestValue)
}
// SetStencilTest configures or disables stencil testing. When stencil testing is
// enabled, the geometry of everything that is drawn afterward will be clipped/stencilled
// out based on a comparison between the arguments of this function and the stencil
// value of each pixel that the geometry touches. The stencil values of pixels are
// affected via Stencil/StencilEXT.
func SetStencilTest(compare CompareMode, value int32) {
if gl_state.writingToStencil {
return
}
states.back().stencilCompare = compare
states.back().stencilTestValue = value
if compare == COMPARE_ALWAYS {
gl.Disable(gl.STENCIL_TEST)
return
}
if gl_state.currentCanvas != nil {
gl_state.currentCanvas.checkCreateStencil()
}
gl.Enable(gl.STENCIL_TEST)
gl.StencilFunc(gl.Enum(compare), int(value), 0xFF)
gl.StencilOp(gl.KEEP, gl.KEEP, gl.REPLACE)
}
// SetScissor Sets or disables scissor. The scissor limits the drawing area to a
// specified rectangle. This affects all graphics calls, including Clear. The
// dimensions of the scissor is unaffected by graphical transformations
// (translate, scale, ...). if no arguments are given it will disable the scissor.
// if x, y, w, h are given it will enable the scissor
func SetScissor(args ...int32) {
if args == nil {
gl.Disable(gl.SCISSOR_TEST)
states.back().scissor = false
} else if len(args) == 4 {
x, y, width, height := args[0], args[1], args[2], args[3]
gl.Enable(gl.SCISSOR_TEST)
if gl_state.currentCanvas != nil {
gl.Scissor(x, y, width, height)
} else {
// With no Canvas active, we need to compensate for glScissor starting
// from the lower left of the viewport instead of the top left.
gl.Scissor(x, gl_state.viewport[3]-(y+height), width, height)
}
states.back().scissorBox = []int32{x, y, width, height}
states.back().scissor = true
} else {
panic("incorrect number of arguments to setscissor")
}
}
// 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)
}