77 lines
2.2 KiB
Go
Executable file
77 lines
2.2 KiB
Go
Executable file
package xmobilebackend
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import (
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"unsafe"
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"github.com/tfriedel6/canvas/backend/backendbase"
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"golang.org/x/mobile/gl"
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)
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func (b *XMobileBackend) ClearClip() {
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b.activate()
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b.glctx.StencilMask(0xFF)
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b.glctx.Clear(gl.STENCIL_BUFFER_BIT)
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}
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func (b *XMobileBackend) Clip(pts []backendbase.Vec) {
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b.activate()
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b.ptsBuf = b.ptsBuf[:0]
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b.ptsBuf = append(b.ptsBuf,
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0, 0,
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0, float32(b.fh),
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float32(b.fw), float32(b.fh),
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float32(b.fw), 0)
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for _, pt := range pts {
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b.ptsBuf = append(b.ptsBuf, float32(pt[0]), float32(pt[1]))
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}
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mode := gl.Enum(gl.TRIANGLES)
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if len(pts) == 4 {
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mode = gl.TRIANGLE_FAN
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}
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b.glctx.BindBuffer(gl.ARRAY_BUFFER, b.buf)
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b.glctx.BufferData(gl.ARRAY_BUFFER, byteSlice(unsafe.Pointer(&b.ptsBuf[0]), len(b.ptsBuf)*4), gl.STREAM_DRAW)
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b.glctx.VertexAttribPointer(b.shd.Vertex, 2, gl.FLOAT, false, 0, 0)
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b.glctx.VertexAttribPointer(b.shd.TexCoord, 2, gl.FLOAT, false, 0, 0)
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b.glctx.UseProgram(b.shd.ID)
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b.glctx.Uniform4f(b.shd.Color, 1, 1, 1, 1)
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b.glctx.Uniform2f(b.shd.CanvasSize, float32(b.fw), float32(b.fh))
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b.glctx.UniformMatrix3fv(b.shd.Matrix, mat3identity[:])
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b.glctx.Uniform1f(b.shd.GlobalAlpha, 1)
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b.glctx.Uniform1i(b.shd.UseAlphaTex, 0)
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b.glctx.Uniform1i(b.shd.Func, shdFuncSolid)
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b.glctx.EnableVertexAttribArray(b.shd.Vertex)
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b.glctx.EnableVertexAttribArray(b.shd.TexCoord)
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b.glctx.ColorMask(false, false, false, false)
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// set bit 2 in the stencil buffer in the given shape
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b.glctx.StencilMask(0x04)
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b.glctx.StencilFunc(gl.ALWAYS, 4, 0)
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b.glctx.StencilOp(gl.REPLACE, gl.REPLACE, gl.REPLACE)
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b.glctx.DrawArrays(mode, 4, len(pts))
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// on entire screen, where neither bit 1 or 2 are set, invert bit 1
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b.glctx.StencilMask(0x02)
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b.glctx.StencilFunc(gl.EQUAL, 0, 0x06)
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b.glctx.StencilOp(gl.KEEP, gl.INVERT, gl.INVERT)
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b.glctx.DrawArrays(gl.TRIANGLE_FAN, 0, 4)
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// on entire screen, clear bit 2
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b.glctx.StencilMask(0x04)
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b.glctx.StencilFunc(gl.ALWAYS, 0, 0)
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b.glctx.StencilOp(gl.ZERO, gl.ZERO, gl.ZERO)
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b.glctx.DrawArrays(gl.TRIANGLE_FAN, 0, 4)
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b.glctx.DisableVertexAttribArray(b.shd.Vertex)
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b.glctx.DisableVertexAttribArray(b.shd.TexCoord)
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b.glctx.ColorMask(true, true, true, true)
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b.glctx.StencilOp(gl.KEEP, gl.KEEP, gl.KEEP)
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b.glctx.StencilMask(0xFF)
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b.glctx.StencilFunc(gl.EQUAL, 0, 0xFF)
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}
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