ebiten/graphics/opengl/context.go

package opengl

// #cgo LDFLAGS: -framework OpenGL
//
// #include <stdlib.h>
// #include <OpenGL/gl.h>
import "C"
import (
	"github.com/hajimehoshi/go-ebiten/graphics"
	"github.com/hajimehoshi/go-ebiten/graphics/matrix"
	"github.com/hajimehoshi/go-ebiten/graphics/opengl/rendertarget"
	"github.com/hajimehoshi/go-ebiten/graphics/opengl/shader"
	"github.com/hajimehoshi/go-ebiten/graphics/opengl/texture"
	grendertarget "github.com/hajimehoshi/go-ebiten/graphics/rendertarget"
	gtexture "github.com/hajimehoshi/go-ebiten/graphics/texture"
	"image"
	"math"
)

type Context struct {
	screenId               graphics.RenderTargetId
	screenWidth            int
	screenHeight           int
	screenScale            int
	ids                    *ids
	mainFramebufferTexture *grendertarget.RenderTarget
	projectionMatrix       [16]float32
}

func newContext(screenWidth, screenHeight, screenScale int) *Context {
	context := &Context{
		screenWidth:  screenWidth,
		screenHeight: screenHeight,
		screenScale:  screenScale,
		ids:          newIds(),
	}

	// The main framebuffer should be created sooner than any other
	// framebuffers!
	mainFramebuffer := C.GLint(0)
	C.glGetIntegerv(C.GL_FRAMEBUFFER_BINDING, &mainFramebuffer)

	var err error
	context.mainFramebufferTexture, err = rendertarget.NewWithFramebuffer(
		context.screenWidth*context.screenScale,
		context.screenHeight*context.screenScale,
		rendertarget.Framebuffer(mainFramebuffer))
	if err != nil {
		panic("creating main framebuffer failed: " + err.Error())
	}

	context.screenId, err = context.createRenderTarget(
		context.screenWidth, context.screenHeight, texture.FilterNearest)
	if err != nil {
		panic("initializing the offscreen failed: " + err.Error())
	}

	context.Init()

	return context
}

func (context *Context) ToTexture(renderTargetId graphics.RenderTargetId) graphics.TextureId {
	return context.ids.ToTexture(renderTargetId)
}

func (context *Context) Clear() {
	context.Fill(0, 0, 0)
}

func (context *Context) Fill(r, g, b uint8) {
	const max = float64(math.MaxUint8)
	C.glClearColor(
		C.GLclampf(float64(r)/max),
		C.GLclampf(float64(g)/max),
		C.GLclampf(float64(b)/max),
		1)
	C.glClear(C.GL_COLOR_BUFFER_BIT)
}

func (context *Context) DrawTexture(
	textureId graphics.TextureId,
	geometryMatrix matrix.Geometry, colorMatrix matrix.Color) {
	tex := context.ids.TextureAt(textureId)
	tex.Draw(func(native interface{}, quads []gtexture.Quad) {
		shader.DrawTexture(native.(texture.Native),
			context.projectionMatrix, quads,
			geometryMatrix, colorMatrix)
	})
}

func (context *Context) DrawTextureParts(
	textureId graphics.TextureId, parts []graphics.TexturePart,
	geometryMatrix matrix.Geometry, colorMatrix matrix.Color) {
	tex := context.ids.TextureAt(textureId)
	tex.DrawParts(parts, func(native interface{}, quads []gtexture.Quad) {
		shader.DrawTexture(native.(texture.Native),
			context.projectionMatrix, quads,
			geometryMatrix, colorMatrix)
	})
}

func (context *Context) Init() {
	C.glEnable(C.GL_TEXTURE_2D)
	C.glEnable(C.GL_BLEND)
}

func (context *Context) ResetOffscreen() {
	context.SetOffscreen(context.screenId)
}

func (context *Context) SetOffscreen(renderTargetId graphics.RenderTargetId) {
	renderTarget := context.ids.RenderTargetAt(renderTargetId)
	context.setOffscreen(renderTarget)
}

func (context *Context) setOffscreen(rt *grendertarget.RenderTarget) {
	C.glFlush()

	setter := &OffscreenSetter{
		context.screenHeight,
		context.screenScale,
		rt == context.mainFramebufferTexture,
		&context.projectionMatrix,
	}
	rt.SetAsOffscreen(setter)
}

func (context *Context) setMainFramebufferOffscreen() {
	context.setOffscreen(context.mainFramebufferTexture)
}

func (context *Context) flush() {
	C.glFlush()
}

func (context *Context) createRenderTarget(width, height int, filter texture.Filter) (
	graphics.RenderTargetId, error) {
	renderTargetId, err := context.ids.CreateRenderTarget(width, height, filter)
	if err != nil {
		return 0, err
	}
	return renderTargetId, nil
}

func (context *Context) NewRenderTarget(width, height int) (
	graphics.RenderTargetId, error) {
	return context.createRenderTarget(width, height, texture.FilterLinear)
}

func (context *Context) NewTextureFromImage(img image.Image) (
	graphics.TextureId, error) {
	return context.ids.CreateTextureFromImage(img)
}