Documentation ¶
Index ¶
- Constants
- func CaptureRGBA(im *image.RGBA)
- func CaptureToPng(filename string)
- func CheckGLError() error
- func ClearAlpha(alpha_value gl.GLclampf)
- func ColorC(c color.Color)
- func DebugLines()
- func DrawAxes()
- func DrawQuadd(x, y, w, h float64)
- func DrawQuadi(x, y, w, h int)
- func GetViewportWH() (int, int)
- func GetViewportWHD() (float64, float64)
- func IsPow2(x uint32) bool
- func MakeShader(shader_type uint32, source string) uint32
- func NewProgram(shaders ...Shader) uint32
- func OpenGLSentinel() func()
- func Pow2(x uint32) uint32
- func Pow2Image(src image.Image) image.Image
- func ProjToWindow(x, y float64) (float64, float64)
- func Sizeof(gtype uint32) uint
- func Squared(x, y, w, h float64)
- func Squarei(x, y, w, h int)
- func WindowToProj(x, y int) (float64, float64)
- func With(c Context, action func())
- type AtlasRegion
- type Attr
- func NewAttr(name string, size int, typ, usage uint32) *Attr
- func NewColorAttr(size int, typ, usage uint32) *Attr
- func NewIndexAttr(size int, typ, usage uint32) *Attr
- func NewNormalAttr(size int, typ, usage uint32) *Attr
- func NewPositionAttr(size int, typ, usage uint32) *Attr
- func NewTexCoordAttr(size int, typ, usage uint32) *Attr
- func (a *Attr) Clear()
- func (a *Attr) Data() interface{}
- func (a *Attr) Invalid() bool
- func (a *Attr) Invalidate()
- func (a *Attr) Len() int
- func (a *Attr) Name() string
- func (a *Attr) SetTarget(t uint32)
- func (a *Attr) Size() int
- func (a *Attr) Stride() int
- func (a *Attr) Target() uint32
- func (a *Attr) Type() uint32
- type Attrib
- type CompoundContextImpl
- type Context
- type Framebuffer
- type Matrix
- type Mesh
- type MeshBuffer
- func (mb *MeshBuffer) Add(argv ...interface{}) int
- func (mb *MeshBuffer) Attr(name string) *Attr
- func (mb *MeshBuffer) Clear()
- func (mb *MeshBuffer) Colors() *Attr
- func (mb *MeshBuffer) Indices() *Attr
- func (mb *MeshBuffer) Meshes() []Mesh
- func (mb *MeshBuffer) Mode() RenderMode
- func (mb *MeshBuffer) Normals() *Attr
- func (mb *MeshBuffer) Positions() *Attr
- func (mb *MeshBuffer) Release()
- func (mb *MeshBuffer) Render(mode uint32)
- func (mb *MeshBuffer) RenderMesh(index int, mode uint32)
- func (mb *MeshBuffer) TexCoords() *Attr
- type Primitive
- type RenderMode
- type Shader
- type Texture
- type TextureAtlas
- func (a *TextureAtlas) Allocate(width, height int32) (AtlasRegion, bool)
- func (a *TextureAtlas) Bind(target uint32)
- func (a *TextureAtlas) Clear()
- func (a *TextureAtlas) Commit(target uint32)
- func (a *TextureAtlas) Depth() int32
- func (a *TextureAtlas) Height() int32
- func (a *TextureAtlas) Release()
- func (a *TextureAtlas) Save(file string) (err error)
- func (a *TextureAtlas) Set(region AtlasRegion, src []byte, stride int32)
- func (a *TextureAtlas) Unbind(target uint32)
- func (a *TextureAtlas) Width() int32
- type WindowCoords
Constants ¶
const ( // Classic mode uses manual glBegin/glEnd calls to construct the // mesh. This is extremely slow, and mostly only useful for debugging // purposes. This implies OpenGL version 'Ye Olde'+. RenderClassic = iota // Arrays mode uses vertex arrays which involves gl*Pointer calls and // directly passing in the vertex data. This is slower than using VBO's, // because the data has to be uploaded to the GPU on every render pass. // It is useful for older systems where glBufferData is not available. // This implies OpenGL version 1.5+. RenderArrays // Buffered mode uses VBO's. This is the preferred mode for systems // where shader support is not present or deemed necessary. This implies // OpenGL version 2.1+. RenderBuffered )
Known render modes.
Variables ¶
This section is empty.
Functions ¶
func CaptureRGBA ¶
func CaptureToPng ¶
func CaptureToPng(filename string)
Note: You may want to call ClearAlpha(1) first..
func ClearAlpha ¶
Clear the alpha channel in the color buffer
func DebugLines ¶
func DebugLines()
Draws a cross on the screen with known lengths, useful for understanding screen dimensions
func DrawQuadi ¶
func DrawQuadi(x, y, w, h int)
Draw a Quad with integer co-ordinates (Using Squarei)
func GetViewportWHD ¶
func MakeShader ¶
func NewProgram ¶
func OpenGLSentinel ¶
func OpenGLSentinel() func()
Used as "defer OpenGLSentinel()()" checks the gl error code on call and exit
func Pow2 ¶
Pow2 returns the first power-of-two value >= to n. This can be used to create suitable texture dimensions.
func Pow2Image ¶
Pow2Image returns the given image, scaled to the smallest power-of-two dimensions larger or equal to the input dimensions. It preserves the image format and contents.
This is useful if an image is to be used as an OpenGL texture. These often require image data to have power-of-two dimensions.
func ProjToWindow ¶
Returns x, y in window co-ordinates at 0 in the z direction
func Squarei ¶
func Squarei(x, y, w, h int)
Emit Vertices of a square with texture co-ordinates which wind anti-clockwise
func WindowToProj ¶
Returns x, y in window co-ordinates at 0 in the z direction
func With ¶
func With(c Context, action func())
I like python. Therefore `func With`. Useful to ensure that changes to state don't leak further than you would like and to insert implicit error checking Example usage:
With(Matrix{gl.PROJECTION}, func() { .. operations which modify matrix .. }) // Changes to the matrix are undone here
Types ¶
type AtlasRegion ¶
A region denotes an allocated chunk of space in an atlas.
type Attr ¶
type Attr struct {
// contains filtered or unexported fields
}
An Attr describes the type and size of a single vertex component. These tell the MeshBuffer how to interpret mesh data.
func NewAttr ¶
NewAttr creates a new mesh attribute for the given size, type, usage value and name.
In RenderShader mode, the name is the variable by which the component can be referenced from a shader program.
In other modes, the MeshBuffer uses this name to identify the attribute's purpose. In these cases, it is advised to use the NewIndexAttr, NewPositionAttr, etc. wrappers.
func NewColorAttr ¶
NewColorAttr creates a new vertex color attribute.
func NewIndexAttr ¶
NewIndexAttr creates a new index attribute.
func NewNormalAttr ¶
NewNormalAttr creates a new surface normal attribute.
func NewPositionAttr ¶
NewPositionAttr creates a new vertex position attribute.
func NewTexCoordAttr ¶
NewTexCoordAttr creates a new vertex texture coordinate attribute.
func (*Attr) Data ¶
func (a *Attr) Data() interface{}
Data returns the atribute data store.
This value should be asserted to a concrete type, which would be a slice of the attrbute's type. E.g.: []float32, []uint8, etc.
func (*Attr) Invalidate ¶
func (a *Attr) Invalidate()
Invalidate marks the data store as invalid. This should be done any time the data is modified externally. It will be re-committed on the next render pass.
type CompoundContextImpl ¶
type CompoundContextImpl struct {
// contains filtered or unexported fields
}
func Compound ¶
func Compound(contexts ...Context) CompoundContextImpl
Combine multiple contexts into one
func (CompoundContextImpl) Enter ¶
func (c CompoundContextImpl) Enter()
func (CompoundContextImpl) Exit ¶
func (c CompoundContextImpl) Exit()
type Context ¶
type Context interface { Enter() Exit() }
Types implementing Context can be used with `With`
type Framebuffer ¶
During this context, OpenGL drawing operations will instead render to `*Texture`. Example usage:
With(Framebuffer{my_texture}, func() { .. operations to render to texture .. })
Internally this will permanently allocate a framebuffer with the appropriate dimensions. Beware that using a large number of textures with differing sizes will therefore cause some graphics cards to run out of memory.
func (*Framebuffer) BindFramebuffer ¶
func (b *Framebuffer) BindFramebuffer(target uint32)
func (*Framebuffer) Enter ¶
func (b *Framebuffer) Enter()
func (*Framebuffer) Exit ¶
func (b *Framebuffer) Exit()
type Matrix ¶
type Matrix struct{ Type uint32 }
A context which preserves the matrix mode, drawing, etc.
type MeshBuffer ¶
type MeshBuffer struct {
// contains filtered or unexported fields
}
MeshBuffer represents a mesh buffer. It caches and renders vertex data for an arbitrary amount of independent meshes.
func NewMeshBuffer ¶
func NewMeshBuffer(mode RenderMode, attr ...*Attr) *MeshBuffer
NewMeshBuffer returns a new mesh buffer object.
The mode parameter defines the mode in which this buffer treats and renders vertex data. It should hold one of the predefined RenderMode constants.
The given attributes define the type and size of each vertex component. For example:
mb := NewMeshBuffer( // Render our data using VBO's. glh.RenderBuffered, // Indices: 1 unsigned short per index; static data. NewIndexAttr(1, gl.USIGNED_SHORT, gl.STATIC_DRAW), // Positions: 3 floats; static data. NewPositionAttr(3, gl.FLOAT, gl.STATIC_DRAW), // Colors: 4 floats; changing regularly. NewColorAttr(4, gl.FLOAT, gl.DYNAMIC_DRAW), )
Any mesh data loaded into this buffer through MeshBuffer.Add(), must adhere to the format defined by these attributes. THis includes the order in which the data is supplied. It must match the order in which the attributes are defined here.
func (*MeshBuffer) Add ¶
func (mb *MeshBuffer) Add(argv ...interface{}) int
Add appends new mesh data to the buffer.
The data specified in these lists should match the buffer attributes. We expect to receive lists like []float32, []byte in the same order as the attributes where supplied to NewMeshBuffer.
Returns an index into the MeshBuffer.Meshes() list.
func (*MeshBuffer) Attr ¶
func (mb *MeshBuffer) Attr(name string) *Attr
Attr returns the attribute for the given name.
func (*MeshBuffer) Colors ¶
func (mb *MeshBuffer) Colors() *Attr
Colors returns the mesh attribute for color data. This is relevant only for render modes other than RenderShader.
func (*MeshBuffer) Indices ¶
func (mb *MeshBuffer) Indices() *Attr
Indices returns the mesh attribute for index data. This is relevant only for render modes other than RenderShader.
func (*MeshBuffer) Meshes ¶
func (mb *MeshBuffer) Meshes() []Mesh
Meshes returns a list of meshes in the buffer.
func (*MeshBuffer) Mode ¶
func (mb *MeshBuffer) Mode() RenderMode
Mode returns the render mode for this buffer.
func (*MeshBuffer) Normals ¶
func (mb *MeshBuffer) Normals() *Attr
Normals returns the mesh attribute for normal data. This is relevant only for render modes other than RenderShader.
func (*MeshBuffer) Positions ¶
func (mb *MeshBuffer) Positions() *Attr
Positions returns the mesh attribute for position data. This is relevant only for render modes other than RenderShader.
func (*MeshBuffer) Release ¶
func (mb *MeshBuffer) Release()
Release releases all resources for this buffer.
func (*MeshBuffer) Render ¶
func (mb *MeshBuffer) Render(mode uint32)
Render renders the entire mesh buffer. The mode defines one of the symbolic constants like GL_TRIANGLES, GL_QUADS, GL_POLYGON, GL_TRIANGLE_STRIP, etc.
func (*MeshBuffer) RenderMesh ¶
func (mb *MeshBuffer) RenderMesh(index int, mode uint32)
RenderMesh renders a single mesh, idenfified by its index. The mode defines one of the symbolic constants like GL_TRIANGLES, GL_QUADS, GL_POLYGON, GL_TRIANGLE_STRIP, etc.
func (*MeshBuffer) TexCoords ¶
func (mb *MeshBuffer) TexCoords() *Attr
TexCoords returns the mesh attribute for texture coordinate data. This is relevant only for render modes other than RenderShader.
type Primitive ¶
type Primitive struct{ Type uint32 }
Context which does `gl.Begin` and `gl.End` Example:
With(Primitive{gl.LINES}, func() { gl.Vertex2f(0, 0); gl.Vertex2f(1,1) })
type RenderMode ¶
type RenderMode uint8
A RenderMode determines how a MeshBuffer should buffer and render mesh data.
type Texture ¶
type Texture struct {
W, H int
// contains filtered or unexported fields
}
A 2D Texture which implements Context, so can be used as:
`With(texture, func() { .. textured primitives .. })`
which sets gl.ENABLE_BIT
func NewTexture ¶
Create a new texture, initialize it to have a `gl.LINEAR` filter and use `gl.CLAMP_TO_EDGE`.
type TextureAtlas ¶
type TextureAtlas struct {
// contains filtered or unexported fields
}
A texture atlas is used to tightly pack arbitrarily many small images into a single texture.
The actual implementation is based on the article by Jukka Jylänki: "A Thousand Ways to Pack the Bin - A Practical Approach to Two-Dimensional Rectangle Bin Packing", February 27, 2010.
More precisely, this is an implementation of the 'Skyline Bottom-Left' algorithm.
func NewTextureAtlas ¶
func NewTextureAtlas(width, height, depth int32) *TextureAtlas
NewAtlas creates a new texture atlas.
The given width, height and depth determine the size and depth of the underlying texture.
depth should be 1, 3 or 4 and it will specify if the texture is created with Alpha, RGB or RGBA channels. The image data supplied through Atlas.Set() should be of the same format.
func (*TextureAtlas) Allocate ¶
func (a *TextureAtlas) Allocate(width, height int32) (AtlasRegion, bool)
Allocate allocates a new region of the given dimensions in the atlas. It returns false if the allocation failed. This can happen when the specified dimensions exceed atlas bounds, or the atlas is full.
func (*TextureAtlas) Bind ¶
func (a *TextureAtlas) Bind(target uint32)
Bind binds the atlas texture, so it can be used for rendering.
func (*TextureAtlas) Clear ¶
func (a *TextureAtlas) Clear()
Clear removes all allocated regions from the atlas. This invalidates any previously allocated regions.
func (*TextureAtlas) Commit ¶
func (a *TextureAtlas) Commit(target uint32)
Commit creates the actual texture from the atlas image data. This should be called after all regions have been defined and set, and before you start using the texture for display.
func (*TextureAtlas) Depth ¶
func (a *TextureAtlas) Depth() int32
Depth returns the underlying texture color depth.
func (*TextureAtlas) Height ¶
func (a *TextureAtlas) Height() int32
Height returns the underlying texture height in pixels.
func (*TextureAtlas) Save ¶
func (a *TextureAtlas) Save(file string) (err error)
Save saves the texture as a PNG image.
func (*TextureAtlas) Set ¶
func (a *TextureAtlas) Set(region AtlasRegion, src []byte, stride int32)
Set pastes the given data into the atlas buffer at the given coordinates. It assumes there is enough space available for the data to fit.
func (*TextureAtlas) Unbind ¶
func (a *TextureAtlas) Unbind(target uint32)
Unbind unbinds the current texture. Note that this applies to any texture currently active. If this is not the atlas texture, it will still perform the action.
func (*TextureAtlas) Width ¶
func (a *TextureAtlas) Width() int32
Width returns the underlying texture width in pixels.
type WindowCoords ¶
Set the GL_PROJECTION matrix to use window co-ordinates and load the identity matrix into the GL_MODELVIEW matrix
func (WindowCoords) Enter ¶
func (wc WindowCoords) Enter()
func (WindowCoords) Exit ¶
func (wc WindowCoords) Exit()