mirror of
https://github.com/hajimehoshi/ebiten.git
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120 lines
2.5 KiB
Go
120 lines
2.5 KiB
Go
package opengl
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// #cgo LDFLAGS: -framework OpenGL
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//
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// #include <stdlib.h>
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// #include <OpenGL/gl.h>
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import "C"
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import (
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"github.com/hajimehoshi/ebiten/graphics"
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"github.com/hajimehoshi/ebiten/graphics/matrix"
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)
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func enableAlphaBlending() {
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C.glEnable(C.GL_TEXTURE_2D)
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C.glEnable(C.GL_BLEND)
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}
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func flush() {
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C.glFlush()
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}
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type Context struct {
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screenId graphics.RenderTargetId
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defaultId graphics.RenderTargetId
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currentId graphics.RenderTargetId
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screenWidth int
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screenHeight int
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screenScale int
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}
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func NewContext(screenWidth, screenHeight, screenScale int) *Context {
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context := &Context{
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screenWidth: screenWidth,
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screenHeight: screenHeight,
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screenScale: screenScale,
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}
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defaultRenderTarget := &RenderTarget{
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width: screenWidth * screenScale,
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height: screenHeight * screenScale,
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flipY: true,
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}
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context.defaultId = idsInstance.addRenderTarget(defaultRenderTarget)
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var err error
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context.screenId, err = idsInstance.createRenderTarget(
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screenWidth, screenHeight, graphics.FilterNearest)
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if err != nil {
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panic("initializing the offscreen failed: " + err.Error())
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}
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context.ResetOffscreen()
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context.Clear()
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enableAlphaBlending()
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return context
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}
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func (c *Context) Dispose() {
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// TODO: remove the default framebuffer?
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idsInstance.deleteRenderTarget(c.screenId)
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}
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func (c *Context) Update(draw func(graphics.Context)) {
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c.ResetOffscreen()
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c.Clear()
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draw(c)
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c.SetOffscreen(c.defaultId)
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c.Clear()
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scale := float64(c.screenScale)
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geo := matrix.IdentityGeometry()
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geo.Scale(scale, scale)
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graphics.DrawWhole(
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c.RenderTarget(c.screenId),
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c.screenWidth,
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c.screenHeight,
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geo,
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matrix.IdentityColor())
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flush()
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}
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func (c *Context) Clear() {
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c.Fill(0, 0, 0)
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}
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func (c *Context) Fill(r, g, b uint8) {
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idsInstance.fillRenderTarget(c.currentId, r, g, b)
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}
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func (c *Context) Texture(id graphics.TextureId) graphics.Drawer {
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return &textureWithContext{id, c}
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}
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func (c *Context) RenderTarget(id graphics.RenderTargetId) graphics.Drawer {
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return &textureWithContext{idsInstance.toTexture(id), c}
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}
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func (c *Context) ResetOffscreen() {
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c.currentId = c.screenId
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}
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func (c *Context) SetOffscreen(renderTargetId graphics.RenderTargetId) {
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c.currentId = renderTargetId
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}
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type textureWithContext struct {
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id graphics.TextureId
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context *Context
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}
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func (t *textureWithContext) Draw(
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parts []graphics.TexturePart,
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geo matrix.Geometry,
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color matrix.Color) {
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idsInstance.drawTexture(t.context.currentId, t.id, parts, geo, color)
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}
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