From d16037c9830d9608ef9d255acde3c4f2e8f66d69 Mon Sep 17 00:00:00 2001
From: faiface <faiface@ksp.sk>
Date: Sat, 3 Dec 2016 16:25:41 +0100
Subject: [PATCH] add Drawer interface and PolygonColor shape
---
graphics.go | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 110 insertions(+)
create mode 100644 graphics.go
diff --git a/graphics.go b/graphics.go
new file mode 100644
index 0000000..3807964
--- /dev/null
+++ b/graphics.go
@@ -0,0 +1,110 @@
+package pixel
+
+import (
+ "image/color"
+
+ "github.com/faiface/pixel/pixelgl"
+ "github.com/go-gl/mathgl/mgl32"
+ "github.com/pkg/errors"
+)
+
+// Drawer is anything that can be drawn. It's by no means a drawer inside your table.
+//
+// Drawer consists of a single method: Draw. Draw methods takes any number of Transform arguments. It applies these
+// transforms in the reverse order and finally draws something transformed by these transforms.
+//
+// Example:
+//
+// // object is a drawer
+// object.Draw(pixel.Position(pixel.V(100, 100).Rotate(math.Pi / 2)))
+// camera := pixel.Camera(pixel.V(0, 0), pixel.V(500, 500), pixel.V(window.Size()))
+// object.Draw(camera, pixel.Position(0).Scale(0.5))
+type Drawer interface {
+ Draw(t ...Transform)
+}
+
+// PolygonColor is a polygon shape filled with a single color.
+type PolygonColor struct {
+ parent pixelgl.Doer
+ color color.Color
+ points []Vec
+ va *pixelgl.VertexArray
+}
+
+// NewPolygonColor creates a new polygon shape filled with a single color. Parent is an object that this shape belongs to,
+// such as a window, or a graphical effect.
+func NewPolygonColor(parent pixelgl.Doer, c color.Color, points ...Vec) *PolygonColor {
+ pc := &PolygonColor{
+ parent: parent,
+ color: c,
+ points: points,
+ }
+
+ var format pixelgl.VertexFormat
+ parent.Do(func(ctx pixelgl.Context) {
+ format = ctx.Shader().VertexFormat()
+ })
+
+ var err error
+ pc.va, err = pixelgl.NewVertexArray(parent, format, pixelgl.TriangleFanDrawMode, pixelgl.DynamicUsage, len(points))
+ if err != nil {
+ panic(errors.Wrap(err, "failed to create polygon"))
+ }
+
+ for i, p := range points {
+ pc.va.SetVertexAttributeVec2(i, pixelgl.Position, mgl32.Vec2{float32(p.X()), float32(p.Y())})
+ pc.va.SetVertexAttributeVec4(i, pixelgl.Color, mgl32.Vec4{1, 1, 1, 1})
+ }
+
+ return pc
+}
+
+// Count returns the number of points in a polygon.
+func (pc *PolygonColor) Count() int {
+ return len(pc.points)
+}
+
+// SetColor changes the color of a polygon to c.
+func (pc *PolygonColor) SetColor(c color.Color) {
+ pc.color = c
+}
+
+// Color returns the current color of a polygon.
+func (pc *PolygonColor) Color() color.Color {
+ return pc.color
+}
+
+// SetPoint changes the position of a point in a polygon.
+//
+// If the index is out of range, this function panics.
+func (pc *PolygonColor) SetPoint(i int, point Vec) {
+ pc.points[i] = point
+ pc.va.SetVertexAttributeVec2(i, pixelgl.Position, mgl32.Vec2{float32(point.X()), float32(point.Y())})
+}
+
+// Point returns the position of a point in a polygon.
+//
+// If the index is out of range, this function panics.
+func (pc *PolygonColor) Point(i int) Vec {
+ return pc.points[i]
+}
+
+// Draw draws a polygon transformed by the supplied transforms applied in the reverse order.
+func (pc *PolygonColor) Draw(t ...Transform) {
+ mat := mgl32.Ident3()
+ for i := range t {
+ mat = mat.Mul3(t[i].Mat3())
+ }
+
+ var shader *pixelgl.Shader
+ pc.parent.Do(func(ctx pixelgl.Context) {
+ shader = ctx.Shader()
+ })
+
+ r, g, b, a := colorToRGBA(pc.color)
+ shader.SetUniformVec4(pixelgl.MaskColor, mgl32.Vec4{r, g, b, a})
+ shader.SetUniformMat3(pixelgl.Transform, mat)
+ shader.SetUniformInt(pixelgl.IsTexture, 0)
+
+ pc.va.Draw()
+}
--
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