123 lines
3.2 KiB
Go
123 lines
3.2 KiB
Go
package render
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import (
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_ "embed"
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"unsafe"
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"edgaru089.ink/go/gl01/internal/util/itype"
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"github.com/go-gl/gl/all-core/gl"
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)
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var (
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screenQuadVerts = []float32{
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-1, -1,
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0, 0,
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1, -1,
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1, 0,
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1, 1,
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1, 1,
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-1, -1,
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0, 0,
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1, 1,
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1, 1,
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-1, 1,
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0, 1,
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}
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screenQuadVAO uint32
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screenQuadVBO uint32
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drawTextureShader *Shader // Shader for dumping textures to screen
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)
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func initScreenQuad() {
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gl.GenBuffers(1, &screenQuadVBO)
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gl.BindBuffer(gl.ARRAY_BUFFER, screenQuadVBO)
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gl.BufferData(gl.ARRAY_BUFFER, int(unsafe.Sizeof(float32(0)))*len(screenQuadVerts), gl.Ptr(screenQuadVerts), gl.STATIC_DRAW)
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gl.GenVertexArrays(1, &screenQuadVAO)
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gl.BindVertexArray(screenQuadVAO)
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gl.VertexAttribPointer(0, 2, gl.FLOAT, false, int32(4*unsafe.Sizeof(float32(0))), gl.PtrOffset(0))
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gl.VertexAttribPointer(1, 2, gl.FLOAT, false, int32(4*unsafe.Sizeof(float32(0))), gl.PtrOffset(int(2*unsafe.Sizeof(float32(0)))))
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gl.EnableVertexAttribArray(0)
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gl.EnableVertexAttribArray(1)
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}
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// DrawScreenQuad draws a Quad covering the entire screen with the current binding shader.
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//
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// Attribute: (location=0) vert: [ -1.0 --> 1.0]
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// (location=1) texCoord: [ 0 --> 1]
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func DrawScreenQuad() {
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if screenQuadVAO == 0 {
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initScreenQuad()
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}
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gl.Disable(gl.DEPTH_TEST)
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gl.Disable(gl.CULL_FACE)
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gl.BindVertexArray(screenQuadVAO)
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gl.DrawArrays(gl.TRIANGLES, 0, 6)
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}
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// DrawTextureChannels specifies the channels in RGBA to be drawn.
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type DrawTextureChannels int
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const (
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DrawTextureChannels_R DrawTextureChannels = 1 << iota
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DrawTextureChannels_G
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DrawTextureChannels_B
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DrawTextureChannels_A
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)
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var (
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//go:embed drawtexture.vert
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drawTextureShaderVert string
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//go:embed drawtexture.frag
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drawTextureShaderFrag string
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)
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func initDrawTexture() {
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var err error
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drawTextureShader, err = NewShader(drawTextureShaderVert, drawTextureShaderFrag)
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if err != nil {
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panic(err)
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}
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gl.BindFragDataLocation(drawTextureShader.Handle(), 0, gl.Str("outputColor\x00"))
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}
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// DrawTexture dumps the contents of a Texture onto the portion of the screen.
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// It disables depth test and cull face.
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//
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// onScreen is specified in [-1, 1] size.
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//
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// If only one channel is specified, that channel is drawn in black and white.
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// Otherwise, R/G/B are drawn in their specified channels and A is ignored.
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//
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// The texture values from vauleRange is mapped to [0, 1] linearly.
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//
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// TODO: This does not work. Maybe something wrong with the shaders or blending
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func DrawTexture(texture uint32, onScreen itype.Rectf, channels DrawTextureChannels, valueMin, valueMax float32) {
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if screenQuadVAO == 0 {
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initScreenQuad()
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}
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if drawTextureShader == nil {
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initDrawTexture()
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}
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drawTextureShader.UseProgram()
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drawTextureShader.SetUniformVec2f("onScreenPos", onScreen.MinPoint())
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drawTextureShader.SetUniformVec2f("onScreenSize", onScreen.Size())
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drawTextureShader.SetUniformFloat("valueMin", valueMin)
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drawTextureShader.SetUniformFloat("valueMax", valueMax)
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drawTextureShader.SetUniformInt("channels", int32(channels))
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drawTextureShader.SetUniformTextureHandle("tex", texture)
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drawTextureShader.BindTextures()
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gl.Disable(gl.DEPTH_TEST)
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gl.Disable(gl.CULL_FACE)
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gl.BindVertexArray(screenQuadVAO)
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gl.DrawArrays(gl.TRIANGLES, 0, 6)
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}
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