From b60db9c2f695b183849a01745cae86175b3106dc Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@hajimehoshi.com>
Date: Wed, 8 Jan 2014 16:38:03 +0900
Subject: [PATCH] Make RenderTarget's fields unexported

---
 graphics/opengl/offscreen/offscreen.go        | 40 ++++++++-----------
 graphics/opengl/rendertarget/render_target.go | 30 ++++++++++++--
 2 files changed, 42 insertions(+), 28 deletions(-)

diff --git a/graphics/opengl/offscreen/offscreen.go b/graphics/opengl/offscreen/offscreen.go
index 4ac9301b0..0eb44403d 100644
--- a/graphics/opengl/offscreen/offscreen.go
+++ b/graphics/opengl/offscreen/offscreen.go
@@ -6,7 +6,6 @@ package offscreen
 // #include <OpenGL/gl.h>
 import "C"
 import (
-	"fmt"
 	"github.com/hajimehoshi/go-ebiten/graphics"
 	"github.com/hajimehoshi/go-ebiten/graphics/matrix"
 	"github.com/hajimehoshi/go-ebiten/graphics/opengl/rendertarget"
@@ -17,8 +16,8 @@ import (
 type Offscreen struct {
 	screenHeight           int
 	screenScale            int
+	currentRenderTarget    *rendertarget.RenderTarget
 	mainFramebufferTexture *rendertarget.RenderTarget
-	projectionMatrix       [16]float32
 }
 
 func New(screenWidth, screenHeight, screenScale int) *Offscreen {
@@ -38,15 +37,15 @@ func New(screenWidth, screenHeight, screenScale int) *Offscreen {
 	if err != nil {
 		panic("creating main framebuffer failed: " + err.Error())
 	}
+	offscreen.currentRenderTarget = offscreen.mainFramebufferTexture
 
 	return offscreen
 }
 
 func (o *Offscreen) Set(rt *rendertarget.RenderTarget) {
 	C.glFlush()
-	// TODO: Calc x, y, width, heigth at another function
-	o.doSet(rt.Framebuffer, 0, 0,
-		graphics.AdjustSizeForTexture(rt.Width), graphics.AdjustSizeForTexture(rt.Height))
+	o.currentRenderTarget = rt
+	rt.SetAsViewport()
 }
 
 func (o *Offscreen) SetMainFramebuffer() {
@@ -55,45 +54,38 @@ func (o *Offscreen) SetMainFramebuffer() {
 
 func (o *Offscreen) DrawTexture(texture *texture.Texture,
 	geometryMatrix matrix.Geometry, colorMatrix matrix.Color) {
+	projectionMatrix := o.projectionMatrix()
 	quad := graphics.TextureQuadForTexture(texture.Width, texture.Height)
 	shader.DrawTexture(texture.Native,
-		o.projectionMatrix, []graphics.TextureQuad{quad},
+		projectionMatrix, []graphics.TextureQuad{quad},
 		geometryMatrix, colorMatrix)
 }
 
 func (o *Offscreen) DrawTextureParts(texture *texture.Texture,
 	parts []graphics.TexturePart,
 	geometryMatrix matrix.Geometry, colorMatrix matrix.Color) {
+	projectionMatrix := o.projectionMatrix()
 	quads := graphics.TextureQuadsForTextureParts(parts, texture.Width, texture.Height)
 	shader.DrawTexture(texture.Native,
-		o.projectionMatrix, quads,
+		projectionMatrix, quads,
 		geometryMatrix, colorMatrix)
 }
 
-func (o *Offscreen) doSet(framebuffer rendertarget.Framebuffer, x, y, width, height int) {
-	C.glBindFramebuffer(C.GL_FRAMEBUFFER, C.GLuint(framebuffer))
-	err := C.glCheckFramebufferStatus(C.GL_FRAMEBUFFER)
-	if err != C.GL_FRAMEBUFFER_COMPLETE {
-		panic(fmt.Sprintf("glBindFramebuffer failed: %d", err))
-	}
-
-	C.glBlendFuncSeparate(C.GL_SRC_ALPHA, C.GL_ONE_MINUS_SRC_ALPHA,
-		C.GL_ZERO, C.GL_ONE)
-
-	C.glViewport(C.GLint(x), C.GLint(y),
-		C.GLsizei(width), C.GLsizei(height))
-
-	matrix := graphics.OrthoProjectionMatrix(x, width, y, height)
-	if framebuffer == o.mainFramebufferTexture.Framebuffer {
+func (o *Offscreen) projectionMatrix() [16]float32 {
+	matrix := o.currentRenderTarget.ProjectionMatrix()
+	if o.currentRenderTarget == o.mainFramebufferTexture {
 		actualScreenHeight := o.screenHeight * o.screenScale
 		// Flip Y and move to fit with the top of the window.
 		matrix[1][1] *= -1
-		matrix[1][3] += float64(actualScreenHeight) / float64(height) * 2
+		matrix[1][3] += float64(actualScreenHeight) /
+			float64(graphics.AdjustSizeForTexture(actualScreenHeight)) * 2
 	}
 
+	projectionMatrix := [16]float32{}
 	for j := 0; j < 4; j++ {
 		for i := 0; i < 4; i++ {
-			o.projectionMatrix[i+j*4] = float32(matrix[i][j])
+			projectionMatrix[i+j*4] = float32(matrix[i][j])
 		}
 	}
+	return projectionMatrix
 }
diff --git a/graphics/opengl/rendertarget/render_target.go b/graphics/opengl/rendertarget/render_target.go
index 8cc67009d..b477a86f5 100644
--- a/graphics/opengl/rendertarget/render_target.go
+++ b/graphics/opengl/rendertarget/render_target.go
@@ -5,6 +5,7 @@ package rendertarget
 // #include <OpenGL/gl.h>
 import "C"
 import (
+	"fmt"
 	"github.com/hajimehoshi/go-ebiten/graphics"
 	"github.com/hajimehoshi/go-ebiten/graphics/opengl/texture"
 )
@@ -12,9 +13,9 @@ import (
 type Framebuffer C.GLuint
 
 type RenderTarget struct {
-	Framebuffer
-	Width  int
-	Height int
+	framebuffer Framebuffer
+	width  int
+	height int
 }
 
 func createFramebuffer(nativeTexture C.GLuint) Framebuffer {
@@ -57,7 +58,28 @@ func CreateWithFramebuffer(width, height int, framebuffer Framebuffer) (
 	return &RenderTarget{framebuffer, width, height}, nil
 }
 
+func (r *RenderTarget) SetAsViewport() {
+	C.glBindFramebuffer(C.GL_FRAMEBUFFER, C.GLuint(r.framebuffer))
+	err := C.glCheckFramebufferStatus(C.GL_FRAMEBUFFER)
+	if err != C.GL_FRAMEBUFFER_COMPLETE {
+		panic(fmt.Sprintf("glBindFramebuffer failed: %d", err))
+	}
+
+	C.glBlendFuncSeparate(C.GL_SRC_ALPHA, C.GL_ONE_MINUS_SRC_ALPHA,
+		C.GL_ZERO, C.GL_ONE)
+
+	width := graphics.AdjustSizeForTexture(r.width)
+	height := graphics.AdjustSizeForTexture(r.height)
+	C.glViewport(0, 0, C.GLsizei(width), C.GLsizei(height))
+}
+
+func (r *RenderTarget) ProjectionMatrix() [4][4]float64 {
+	width := graphics.AdjustSizeForTexture(r.width)
+	height := graphics.AdjustSizeForTexture(r.height)
+	return graphics.OrthoProjectionMatrix(0, width, 0, height)
+}
+
 func (r *RenderTarget) Dispose() {
-	f := C.GLuint(r.Framebuffer)
+	f := C.GLuint(r.framebuffer)
 	C.glDeleteFramebuffers(1, &f)
 }