From bdd173f5bf80fbaaeb1876fd6b36f5c4d66cb993 Mon Sep 17 00:00:00 2001
From: Liam Galvin <liam@liam-galvin.co.uk>
Date: Mon, 29 Oct 2018 09:53:30 +0000
Subject: [PATCH] remove render code from buffer package, add to renderer,
 improve texture drawing efficiency

---
 buffer/cell.go  | 50 --------------------------------------
 gui/gui.go      |  8 +------
 gui/renderer.go | 64 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 57 deletions(-)

diff --git a/buffer/cell.go b/buffer/cell.go
index d5d1457..4821406 100644
--- a/buffer/cell.go
+++ b/buffer/cell.go
@@ -2,8 +2,6 @@ package buffer
 
 import (
 	"image"
-
-	"github.com/go-gl/gl/all-core/gl"
 )
 
 type Cell struct {
@@ -33,54 +31,6 @@ func (cell *Cell) SetImage(img *image.RGBA) {
 
 }
 
-func (cell *Cell) DrawImage(x, y float32) {
-
-	if cell.image == nil {
-		return
-	}
-
-	var tex uint32
-	gl.Enable(gl.TEXTURE_2D)
-	gl.GenTextures(1, &tex)
-	gl.BindTexture(gl.TEXTURE_2D, tex)
-	gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
-	gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
-	gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
-	gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
-
-	gl.TexImage2D(
-		gl.TEXTURE_2D,
-		0,
-		gl.RGBA,
-		int32(cell.image.Bounds().Size().X),
-		int32(cell.image.Bounds().Size().Y),
-		0,
-		gl.RGBA,
-		gl.UNSIGNED_BYTE,
-		gl.Ptr(cell.image.Pix),
-	)
-	gl.BindTexture(gl.TEXTURE_2D, 0)
-	gl.Disable(gl.TEXTURE_2D)
-
-	gl.Disable(gl.BLEND)
-
-	var w float32 = float32(cell.image.Bounds().Size().X)
-	var h float32 = float32(cell.image.Bounds().Size().Y)
-
-	var readFboId uint32
-	gl.GenFramebuffers(1, &readFboId)
-	gl.BindFramebuffer(gl.READ_FRAMEBUFFER, readFboId)
-
-	gl.FramebufferTexture2D(gl.READ_FRAMEBUFFER, gl.COLOR_ATTACHMENT0,
-		gl.TEXTURE_2D, tex, 0)
-	gl.BlitFramebuffer(0, 0, int32(w), int32(h),
-		int32(x), int32(y), int32(x+w), int32(y+h),
-		gl.COLOR_BUFFER_BIT, gl.LINEAR)
-	gl.BindFramebuffer(gl.READ_FRAMEBUFFER, 0)
-	gl.DeleteFramebuffers(1, &readFboId)
-
-}
-
 func (cell *Cell) Attr() CellAttributes {
 	return cell.attr
 }
diff --git a/gui/gui.go b/gui/gui.go
index a642d59..8f144a9 100644
--- a/gui/gui.go
+++ b/gui/gui.go
@@ -247,13 +247,7 @@ func (gui *GUI) Render() error {
 						gui.renderer.DrawCellText(cell, uint(x), uint(y), nil)
 					}
 
-					if cell.Image() != nil {
-						ix := float32(x) * gui.renderer.cellWidth
-						iy := float32(gui.height) - (float32(y+1) * gui.renderer.cellHeight)
-						iy -= float32(cell.Image().Bounds().Size().Y)
-						gl.UseProgram(program)
-						cell.DrawImage(ix, iy)
-					}
+					gui.renderer.DrawCellImage(cell, uint(x), uint(y))
 
 				}
 			}
diff --git a/gui/renderer.go b/gui/renderer.go
index 12f26a8..9b15ed8 100644
--- a/gui/renderer.go
+++ b/gui/renderer.go
@@ -1,6 +1,7 @@
 package gui
 
 import (
+	"image"
 	"math"
 
 	"github.com/go-gl/gl/all-core/gl"
@@ -25,6 +26,7 @@ type OpenGLRenderer struct {
 	config        *config.Config
 	colourAttr    uint32
 	program       uint32
+	textureMap    map[*image.RGBA]uint32
 }
 
 type rectangle struct {
@@ -138,6 +140,7 @@ func NewOpenGLRenderer(config *config.Config, font *glfont.Font, boldFont *glfon
 		config:        config,
 		colourAttr:    colourAttr,
 		program:       program,
+		textureMap:    map[*image.RGBA]uint32{},
 	}
 	r.SetFont(font, boldFont)
 	return r
@@ -253,3 +256,64 @@ func (r *OpenGLRenderer) DrawCellText(cell buffer.Cell, col uint, row uint, colo
 	r.font.Print(x, y, string(cell.Rune()))
 
 }
+
+func (r *OpenGLRenderer) DrawCellImage(cell buffer.Cell, col uint, row uint) {
+
+	img := cell.Image()
+
+	if img == nil {
+		return
+	}
+
+	ix := float32(col) * r.cellWidth
+	iy := float32(r.areaHeight) - (float32(row+1) * r.cellHeight)
+	iy -= float32(cell.Image().Bounds().Size().Y)
+	gl.UseProgram(r.program)
+
+	var tex uint32
+
+	tex, ok := r.textureMap[img]
+	if !ok {
+		gl.Enable(gl.TEXTURE_2D)
+		gl.GenTextures(1, &tex)
+		gl.BindTexture(gl.TEXTURE_2D, tex)
+		gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
+		gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
+		gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
+		gl.TexParameterf(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
+
+		gl.TexImage2D(
+			gl.TEXTURE_2D,
+			0,
+			gl.RGBA,
+			int32(img.Bounds().Size().X),
+			int32(img.Bounds().Size().Y),
+			0,
+			gl.RGBA,
+			gl.UNSIGNED_BYTE,
+			gl.Ptr(img.Pix),
+		)
+		gl.BindTexture(gl.TEXTURE_2D, 0)
+		gl.Disable(gl.TEXTURE_2D)
+
+		gl.Disable(gl.BLEND)
+
+		r.textureMap[img] = tex
+	}
+
+	var w float32 = float32(img.Bounds().Size().X)
+	var h float32 = float32(img.Bounds().Size().Y)
+
+	var readFboId uint32
+	gl.GenFramebuffers(1, &readFboId)
+	gl.BindFramebuffer(gl.READ_FRAMEBUFFER, readFboId)
+
+	gl.FramebufferTexture2D(gl.READ_FRAMEBUFFER, gl.COLOR_ATTACHMENT0,
+		gl.TEXTURE_2D, tex, 0)
+	gl.BlitFramebuffer(0, 0, int32(w), int32(h),
+		int32(ix), int32(iy), int32(ix+w), int32(iy+h),
+		gl.COLOR_BUFFER_BIT, gl.LINEAR)
+	gl.BindFramebuffer(gl.READ_FRAMEBUFFER, 0)
+	gl.DeleteFramebuffers(1, &readFboId)
+
+}