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Adding perspective-corrected texture mapping.
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It's experimental currently - it works by encoding 1/w in the alpha channel of vertices' colors. This would better be done using a custom vertex attribute when Ebitengine supports it.
Internal: Making clamp work with float32s.
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@SolarLune
SolarLune committed Nov 11, 2023
1 parent ae3e8ac commit ec27c53
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Showing 13 changed files with 371 additions and 222 deletions.
127 changes: 80 additions & 47 deletions camera.go
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Original file line number Diff line number Diff line change
Expand Up @@ -43,11 +43,12 @@ const (
type Camera struct {
*Node

RenderDepth bool // If the Camera should attempt to render a depth texture; if this is true, then DepthTexture() will hold the depth texture render results. Defaults to true.
RenderNormals bool // If the Camera should attempt to render a normal texture; if this is true, then NormalTexture() will hold the normal texture render results. Defaults to false.
SectorRendering bool // If the Camera should render using sectors or not; if no sectors are present, then it won't attempt to render with them. Defaults to false.
SectorRenderDepth int // How far out the Camera renders other sectors. Defaults to 1 (so the current sector and its immediate neighbors).
currentSector *Sector
RenderDepth bool // If the Camera should attempt to render a depth texture; if this is true, then DepthTexture() will hold the depth texture render results. Defaults to true.
RenderNormals bool // If the Camera should attempt to render a normal texture; if this is true, then NormalTexture() will hold the normal texture render results. Defaults to false.
SectorRendering bool // If the Camera should render using sectors or not; if no sectors are present, then it won't attempt to render with them. Defaults to false.
SectorRenderDepth int // How far out the Camera renders other sectors. Defaults to 1 (so the current sector and its immediate neighbors).
PerspectiveCorrectedTextureMapping bool // If the Camera should render textures with perspective corrected texture mapping. Defaults to false.
currentSector *Sector
// How many lights (sorted by distance) should be used to render each object, maximum. If it's greater than 0,
// then only that many lights will be considered. If less than or equal to 0 (the default), then all available lights will be used.
MaxLightCount int
Expand Down Expand Up @@ -162,6 +163,8 @@ func NewCamera(w, h int) *Camera {
`//kage:unit pixels
package main
var PerspectiveCorrection int
func encodeDepth(depth float) vec4 {
r := floor(depth * 255) / 255
g := floor(fract(depth * 255) * 255) / 255
Expand All @@ -177,8 +180,18 @@ func NewCamera(w, h int) *Camera {
return dstPos.xy - imageDstOrigin() + imageSrc0Origin()
}
func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
func unpackFloat(input float, precision float) vec2 {
return vec2(input / precision, mod(input, precision) / 0.05)
}
func Fragment(dstPos vec4, srcPos vec2, vc vec4) vec4 {
color := vc
// We store the depth in the alpha channel
unpacked := unpackFloat(vc.a, 256)
z := 1.0 / unpacked.y
srcSize := imageSrc1Size()
// There's atlassing going on behind the scenes here, so:
Expand All @@ -189,6 +202,11 @@ func NewCamera(w, h int) *Camera {
// Divide by the source image size to get the UV coordinates.
tx /= srcSize
if PerspectiveCorrection > 0 {
tx *= z
color.a = unpacked.x
}
// Apply fract() to loop the UV coords around [0-1].
tx = fract(tx)
Expand Down Expand Up @@ -284,6 +302,7 @@ func (camera *Camera) Clone() INode {
clone.orthoScale = camera.orthoScale
clone.SectorRendering = camera.SectorRendering
clone.SectorRenderDepth = camera.SectorRenderDepth
clone.PerspectiveCorrectedTextureMapping = camera.PerspectiveCorrectedTextureMapping

clone.AccumulateColorMode = camera.AccumulateColorMode
newOptions := *camera.AccumulateDrawOptions
Expand Down Expand Up @@ -1227,11 +1246,27 @@ func (camera *Camera) Render(scene *Scene, lights []ILight, models ...*Model) {
colorVertex.DstX = float32(clipped.X)
colorVertex.DstY = float32(clipped.Y)

// We set the UVs back here because we might need to use them if the material has clip alpha enabled.
uvU := float32(mesh.VertexUVs[vertIndex].X * srcW)
// We do 1 - v here (aka Y in texture coordinates) because 1.0 is the top of the texture while 0 is the bottom in UV coordinates,
// but when drawing textures 0 is the top, and the sourceHeight is the bottom.
uvV := float32((1 - mesh.VertexUVs[vertIndex].Y) * srcH)
w := mesh.vertexTransforms[vertIndex].W

var uvU, uvV float32

if camera.PerspectiveCorrectedTextureMapping {

uvU = float32((mesh.VertexUVs[vertIndex].X / w) * srcW)
uvV = float32(((1 - mesh.VertexUVs[vertIndex].Y) / w) * srcH)

// colorVertex.ColorA = 1.0 / float32(w)
// colorVertex.ColorA = colorVertex.ColorA*0.5 + ((1.0 / float32(w)) * 0.5) // Second half of alpha vertex color controls

} else {

// We set the UVs back here because we might need to use them if the material has clip alpha enabled.
uvU = float32(mesh.VertexUVs[vertIndex].X * srcW)
// We do 1 - v here (aka Y in texture coordinates) because 1.0 is the top of the texture while 0 is the bottom in UV coordinates,
// but when drawing textures 0 is the top, and the sourceHeight is the bottom.
uvV = float32((1 - mesh.VertexUVs[vertIndex].Y) * srcH)

}

colorVertex.SrcX = uvU
colorVertex.SrcY = uvV
Expand All @@ -1244,7 +1279,7 @@ func (camera *Camera) Render(scene *Scene, lights []ILight, models ...*Model) {
depthVertex.ColorA = 1

if camera.RenderNormals {
normalVertex = depthVertex
normalVertex = colorVertex
normalVertex.ColorR = float32(mesh.vertexTransformedNormals[vertIndex].X*0.5 + 0.5)
normalVertex.ColorG = float32(mesh.vertexTransformedNormals[vertIndex].Y*0.5 + 0.5)
normalVertex.ColorB = float32(mesh.vertexTransformedNormals[vertIndex].Z*0.5 + 0.5)
Expand All @@ -1271,6 +1306,11 @@ func (camera *Camera) Render(scene *Scene, lights []ILight, models ...*Model) {
colorVertex.ColorB *= mesh.vertexLights[vertIndex].B
}

if camera.PerspectiveCorrectedTextureMapping {
// TODO: Replace this with custom vertex attributes when possible.
colorVertex.ColorA = float32(packFloat(colorVertex.ColorA, 1.0/float32(w), 256))
}

if camera.RenderDepth {

// 3/28/23, TODO: We currently use the transformed vertex positions for rendering the depth texture. Note
Expand Down Expand Up @@ -1306,7 +1346,11 @@ func (camera *Camera) Render(scene *Scene, lights []ILight, models ...*Model) {
depthVertex.ColorR = float32(depth)
depthVertex.ColorG = float32(depth)
depthVertex.ColorB = float32(depth)
depthVertex.ColorA = 1
if camera.PerspectiveCorrectedTextureMapping {
depthVertex.ColorA = colorVertex.ColorA
} else {
depthVertex.ColorA = 1
}

} else if scene.World != nil && scene.World.FogOn {

Expand Down Expand Up @@ -1392,6 +1436,11 @@ func (camera *Camera) Render(scene *Scene, lights []ILight, models ...*Model) {
img = defaultImg
}

perspectiveCorrection := 0
if camera.PerspectiveCorrectedTextureMapping {
perspectiveCorrection = 1
}

// Render the depth map here
if camera.RenderDepth {

Expand Down Expand Up @@ -1425,6 +1474,9 @@ func (camera *Camera) Render(scene *Scene, lights []ILight, models ...*Model) {

shaderOpt := &ebiten.DrawTrianglesShaderOptions{
Images: [4]*ebiten.Image{camera.resultDepthTexture, img},
Uniforms: map[string]any{
"PerspectiveCorrection": perspectiveCorrection,
},
}
camera.depthIntermediate.DrawTrianglesShader(depthVertexList[:vertexListIndex], indexList[:indexListIndex], camera.clipAlphaShader, shaderOpt)

Expand Down Expand Up @@ -1465,18 +1517,20 @@ func (camera *Camera) Render(scene *Scene, lights []ILight, models ...*Model) {
if scene != nil && scene.World != nil {

colorPassShaderOptions.Uniforms = map[string]interface{}{
"Fog": scene.World.fogAsFloatSlice(),
"FogRange": scene.World.FogRange,
"DitherSize": scene.World.DitheredFogSize,
"FogCurve": float32(scene.World.FogCurve),
"BayerMatrix": bayerMatrix,
"Fog": scene.World.fogAsFloatSlice(),
"FogRange": scene.World.FogRange,
"DitherSize": scene.World.DitheredFogSize,
"FogCurve": float32(scene.World.FogCurve),
"BayerMatrix": bayerMatrix,
"PerspectiveCorrection": perspectiveCorrection,
}

} else {

colorPassShaderOptions.Uniforms = map[string]interface{}{
"Fog": []float32{0, 0, 0, 0},
"FogRange": []float32{0, 1},
"Fog": []float32{0, 0, 0, 0},
"FogRange": []float32{0, 1},
"PerspectiveCorrection": perspectiveCorrection,
}

}
Expand Down Expand Up @@ -1651,33 +1705,12 @@ func (camera *Camera) Render(scene *Scene, lights []ILight, models ...*Model) {

}

// func encodeDepth(depth float64) *Color {

// r := math.Floor(depth*255) / 255
// _, f := math.Modf(depth * 255)
// g := math.Floor(f*255) / 255
// _, f = math.Modf(depth * 255 * 255)
// b := f

// if r < 0 {
// r = 0
// } else if r > 1 {
// r = 1
// }
// if g < 0 {
// g = 0
// } else if g > 1 {
// g = 1
// }
// if b < 0 {
// b = 0
// } else if b > 1 {
// b = 1
// }

// return NewColor(float32(r), float32(g), float32(b), 1)

// }
// packFloat packs two numbers into a single float64 with a given precision. 128 is a good number.
func packFloat(input1, input2, precision float32) float32 {
a := float32(int(input1 * precision))
b := input2 * 0.05
return a + b
}

type DrawSprite3dSettings struct {
// The image to render
Expand Down
2 changes: 1 addition & 1 deletion examples/common.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -138,7 +138,7 @@ func NewBasicFreeCam(scene *tetra3d.Scene) BasicFreeCam {
}

freecam.Camera = tetra3d.NewCamera(640, 360)
freecam.Camera.SetFieldOfView(90)
freecam.Camera.SetFieldOfView(60)
freecam.Camera.SetLocalPosition(0, 0, 5)

scene.Root.AddChildren(freecam.Camera)
Expand Down
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