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Fix mitter length cutoff and near plane intersection (#82)
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@IOTRFAFH
IOTRFAFH authored Nov 21, 2024
1 parent 3862253 commit f3e2304
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Showing 10 changed files with 573 additions and 198 deletions.
3 changes: 3 additions & 0 deletions worldwind/src/commonMain/kotlin/earth/worldwind/draw/DrawableLines.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,9 @@ open class DrawableLines protected constructor(): Drawable {
// Use the leader's line width in screen pixels.
program.loadLineWidth(lineWidth)

// Set cutoff to 10 to avoid possible cutoff at small values of miter length
program.loadMiterLengthCutoff(10f)

// Disable depth testing if requested.
if (!enableDepthTest) dc.gl.disable(GL_DEPTH_TEST)

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8 changes: 5 additions & 3 deletions worldwind/src/commonMain/kotlin/earth/worldwind/draw/DrawableShape.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,10 @@ open class DrawableShape protected constructor(): Drawable {
// Use the draw context's modelview projection matrix, transformed to shape local coordinates.
if (drawState.depthOffset != 0.0) {
mvpMatrix.copy(dc.projection).offsetProjectionDepth(drawState.depthOffset)
program.loadClipDistance((mvpMatrix.m[11] / (mvpMatrix.m[10] - 1.0)).toFloat() / 2.0f) // nearPlane / 2.0f
mvpMatrix.multiplyByMatrix(dc.modelview)
} else {
program.loadClipDistance((dc.projection.m[11] / (dc.projection.m[10] - 1.0)).toFloat() / 2.0f) // nearPlane / 2.0f
mvpMatrix.copy(dc.modelviewProjection)
}
mvpMatrix.multiplyByTranslation(
Expand Down Expand Up @@ -73,9 +75,9 @@ open class DrawableShape protected constructor(): Drawable {
program.enableOneVertexMode(false)
program.loadScreen(dc.viewport.width.toFloat(), dc.viewport.height.toFloat())
dc.gl.vertexAttribPointer(0 /*pointA*/, 4, GL_FLOAT, false, 20, 0)
dc.gl.vertexAttribPointer(1 /*pointB*/, 4, GL_FLOAT, false, 20, 40)
dc.gl.vertexAttribPointer(2 /*pointC*/, 4, GL_FLOAT, false, 20, 80)
dc.gl.vertexAttribPointer(3 /*texCoord*/, 1, GL_FLOAT, false, 20, 56)
dc.gl.vertexAttribPointer(1 /*pointB*/, 4, GL_FLOAT, false, 20, 80)
dc.gl.vertexAttribPointer(2 /*pointC*/, 4, GL_FLOAT, false, 20, 160)
dc.gl.vertexAttribPointer(3 /*texCoord*/, 1, GL_FLOAT, false, 20, 96)
} else {
program.enableOneVertexMode(true)
dc.gl.vertexAttribPointer(0 /*vertexPoint*/, 3, GL_FLOAT, false, drawState.vertexStride, 0)
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16 changes: 8 additions & 8 deletions worldwind/src/commonMain/kotlin/earth/worldwind/draw/DrawableSurfaceShape.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -120,6 +120,8 @@ open class DrawableSurfaceShape protected constructor(): Drawable {
-terrainSector.minLatitude.inDegrees,
0.0
)
program.loadClipDistance((textureMvpMatrix.m[11] / (textureMvpMatrix.m[10] - 1.0)).toFloat() / 2.0f) // set value here, but matrix is orthographic and shader clipping won't work as vertices projected orthographically always have .w == 1
program.loadScreen(colorAttachment.width.toFloat(), colorAttachment.height.toFloat())
for (element in scratchList) {
// Get the shape.
val shape = element as DrawableSurfaceShape
Expand All @@ -135,17 +137,13 @@ open class DrawableSurfaceShape protected constructor(): Drawable {
shape.drawState.vertexOrigin.z
)
program.loadModelviewProjection(mvpMatrix)
program.enableOneVertexMode(!shape.drawState.isLine)
if (shape.drawState.isLine) {
program.enableOneVertexMode(false)
program.loadScreen(colorAttachment.width.toFloat(), colorAttachment.height.toFloat())

dc.gl.vertexAttribPointer(0 /*pointA*/, 4, GL_FLOAT, false, 20, 0)
dc.gl.vertexAttribPointer(1 /*pointB*/, 4, GL_FLOAT, false, 20, 40)
dc.gl.vertexAttribPointer(2 /*pointC*/, 4, GL_FLOAT, false, 20, 80)
dc.gl.vertexAttribPointer(3 /*vertexTexCoord*/, 1, GL_FLOAT, false, 20, 56)
dc.gl.vertexAttribPointer(1 /*pointB*/, 4, GL_FLOAT, false, 20, 80)
dc.gl.vertexAttribPointer(2 /*pointC*/, 4, GL_FLOAT, false, 20, 160)
dc.gl.vertexAttribPointer(3 /*vertexTexCoord*/, 1, GL_FLOAT, false, 20, 96)
} else {
program.enableOneVertexMode(true)

// Use the shape's vertex point attribute.
dc.gl.vertexAttribPointer(0 /*vertexPoint*/, 3, GL_FLOAT, false, shape.drawState.vertexStride, 0)
dc.gl.vertexAttribPointer(1 /*vertexPoint*/, 3, GL_FLOAT, false, shape.drawState.vertexStride, 0)
Expand Down Expand Up @@ -210,12 +208,14 @@ open class DrawableSurfaceShape protected constructor(): Drawable {
program.loadTexCoordMatrix(identityMatrix3)
program.loadColor(color)
program.loadOpacity(opacity)
program.loadScreen(dc.viewport.width.toFloat(), dc.viewport.height.toFloat())

// Use the draw context's modelview projection matrix, transformed to terrain local coordinates.
val terrainOrigin = terrain.vertexOrigin
mvpMatrix.copy(dc.modelviewProjection)
mvpMatrix.multiplyByTranslation(terrainOrigin.x, terrainOrigin.y, terrainOrigin.z)
program.loadModelviewProjection(mvpMatrix)
program.loadClipDistance(0.0f)

// Draw the terrain as triangles.
terrain.drawTriangles(dc)
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2 changes: 1 addition & 1 deletion worldwind/src/commonMain/kotlin/earth/worldwind/render/program/AbstractShaderProgram.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,7 @@ abstract class AbstractShaderProgram: RenderResource {
dc.gl.shaderSource(fs, programSources[FRAGMENT_SHADER])
dc.gl.compileShader(fs)

if (dc.gl.getShaderParameteri(vs, GL_COMPILE_STATUS) != GL_TRUE) {
if (dc.gl.getShaderParameteri(fs, GL_COMPILE_STATUS) != GL_TRUE) {
val msg = dc.gl.getShaderInfoLog(fs)
dc.gl.deleteShader(vs)
dc.gl.deleteShader(fs)
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92 changes: 64 additions & 28 deletions worldwind/src/commonMain/kotlin/earth/worldwind/render/program/TriangleShaderProgram.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -11,11 +11,12 @@ open class TriangleShaderProgram : AbstractShaderProgram() {
"""
uniform mat4 mvpMatrix;
uniform float lineWidth;
uniform float invMiterLengthCutoff;
uniform vec2 screen;
uniform vec2 miterLengthCutoff;
uniform vec4 screen;
uniform bool enableTexture;
uniform bool enableOneVertexMode;
uniform mat3 texCoordMatrix;
uniform float clipDistance;
attribute vec4 pointA;
attribute vec4 pointB;
Expand All @@ -27,41 +28,65 @@ open class TriangleShaderProgram : AbstractShaderProgram() {
void main() {
if (enableOneVertexMode) {
/* Transform the vertex position by the modelview-projection matrix. */
gl_Position = mvpMatrix * vec4(pointA.xyz, 1.0);
gl_Position = mvpMatrix * pointA;
} else {
/* Transform the vertex position by the modelview-projection matrix. */
vec4 pointAScreen = mvpMatrix * vec4(pointA.xyz, 1);
vec4 pointBScreen = mvpMatrix * vec4(pointB.xyz, 1);
vec4 pointCScreen = mvpMatrix * vec4(pointC.xyz, 1);
float corner = pointB.w;
vec4 interpolationPoint = pointB.w < 0.0 ? pointAScreen : pointCScreen; // not a mistake, this should be assigned here
pointAScreen = pointAScreen / pointAScreen.w;
pointBScreen = pointBScreen / pointBScreen.w;
pointCScreen = pointCScreen / pointCScreen.w;
if (pointBScreen.w < 0.0) {
pointBScreen = mix(pointBScreen, interpolationPoint, clamp((clipDistance - pointBScreen.w)/(interpolationPoint.w - pointBScreen.w), 0.0, 1.0));
if (pointB.w < 0.0) {
pointCScreen = pointBScreen;
} else {
pointAScreen = pointBScreen;
}
}
if (pointAScreen.w < 0.0) {
pointAScreen = mix(pointAScreen, pointBScreen, clamp((clipDistance - pointAScreen.w)/(pointBScreen.w - pointAScreen.w), 0.0, 1.0));
}
if (pointCScreen.w < 0.0) {
pointCScreen = mix(pointCScreen, pointBScreen, clamp((clipDistance - pointCScreen.w)/(pointBScreen.w - pointCScreen.w), 0.0, 1.0));
}
vec2 eps = vec2(2.0 / screen.x, 2.0 / screen.y);
eps *= 0.1;
pointAScreen.xy = pointAScreen.xy / pointAScreen.w;
pointBScreen.xy = pointBScreen.xy / pointBScreen.w;
pointCScreen.xy = pointCScreen.xy / pointCScreen.w;
if (all(lessThanEqual(abs(pointBScreen.xy - pointAScreen.xy), eps))) {
float eps = 0.2 * length(screen.zw);
if (length(pointBScreen.xy - pointAScreen.xy) < eps) {
pointAScreen.xy = pointBScreen.xy + normalize(pointBScreen.xy - pointCScreen.xy);
}
if (all(lessThanEqual(abs(pointBScreen.xy - pointCScreen.xy), eps))) {
if (length(pointBScreen.xy - pointCScreen.xy) < eps) {
pointCScreen.xy = pointBScreen.xy + normalize(pointBScreen.xy - pointAScreen.xy);
}
if (all(lessThanEqual(abs(pointAScreen.xy - pointCScreen.xy), eps))) {
if (length(pointAScreen.xy - pointCScreen.xy) < eps) {
pointCScreen.xy = pointBScreen.xy + normalize(pointBScreen.xy - pointAScreen.xy);
}
vec2 AB = normalize(normalize(pointBScreen.xy - pointAScreen.xy) * screen);
vec2 BC = normalize(normalize(pointCScreen.xy - pointBScreen.xy) * screen);
vec2 AB = normalize((pointBScreen.xy - pointAScreen.xy) * screen.xy);
vec2 BC = normalize((pointCScreen.xy - pointBScreen.xy) * screen.xy);
vec2 tangent = normalize(AB + BC);
vec2 point = normalize(AB - BC);
vec2 miter = vec2(-tangent.y, tangent.x);
vec2 normalA = vec2(-AB.y, AB.x);
float miterLength = 1.0 / max(dot(miter, normalA), invMiterLengthCutoff);
float miterLength = 1.0 / max(dot(miter, normalA), miterLengthCutoff.y);
gl_Position = pointBScreen;
gl_Position.xy = gl_Position.xy + (corner * miter * lineWidth * miterLength) / screen.xy;
float cornerX = sign(pointB.w);
float cornerY = (pointB.w - cornerX) * 2.0;
if (abs(miterLength - miterLengthCutoff.x) < eps && cornerY * dot(miter, point) > 0.0) {
// trim the corner
gl_Position.xy = pointBScreen.w * (pointBScreen.xy - (cornerX * cornerY * lineWidth * normalA) * screen.zw);
} else {
gl_Position.xy = pointBScreen.w * (pointBScreen.xy + (cornerY * miter * lineWidth * miterLength) * screen.zw);
}
gl_Position.zw = pointBScreen.zw;
}
/* Transform the vertex tex coord by the tex coord matrix. */
Expand Down Expand Up @@ -106,21 +131,23 @@ open class TriangleShaderProgram : AbstractShaderProgram() {
protected val color = Color()
protected var opacity = 1.0f
protected var lineWidth = 1.0f
protected var invMiterLengthCutoff = 1.0f
protected var screenX = 0.0f
protected var screenY = 0.0f
protected var miterLengthCutoff = 2.0f // should be greater than 1.0
protected var screenX = 1.0f
protected var screenY = 1.0f
protected var clipDistance = 0.0f

protected var mvpMatrixId = KglUniformLocation.NONE
protected var colorId = KglUniformLocation.NONE
protected var opacityId = KglUniformLocation.NONE
protected var lineWidthId = KglUniformLocation.NONE
protected var invMiterLengthCutoffId = KglUniformLocation.NONE
protected var miterLengthCutoffId = KglUniformLocation.NONE
protected var screenId = KglUniformLocation.NONE
protected var enablePickModeId = KglUniformLocation.NONE
protected var enableTextureId = KglUniformLocation.NONE
protected var enableOneVertexModeId = KglUniformLocation.NONE
protected var texCoordMatrixId = KglUniformLocation.NONE
protected var texSamplerId = KglUniformLocation.NONE
protected var clipDistanceId = KglUniformLocation.NONE
private val array = FloatArray(16)

override fun initProgram(dc: DrawContext) {
Expand All @@ -136,10 +163,12 @@ open class TriangleShaderProgram : AbstractShaderProgram() {
gl.uniform1f(opacityId, opacity)
lineWidthId = gl.getUniformLocation(program, "lineWidth")
gl.uniform1f(lineWidthId, lineWidth)
invMiterLengthCutoffId = gl.getUniformLocation(program, "invMiterLengthCutoff")
gl.uniform1f(invMiterLengthCutoffId, invMiterLengthCutoff)
miterLengthCutoffId = gl.getUniformLocation(program, "miterLengthCutoff")
gl.uniform2f(miterLengthCutoffId, miterLengthCutoff, 1f / miterLengthCutoff)
screenId = gl.getUniformLocation(program, "screen")
gl.uniform2f(screenId, screenX, screenY)
gl.uniform4f(screenId, screenX, screenY, 1f / screenX, 1f / screenY)
clipDistanceId = gl.getUniformLocation(program, "clipDistance")
gl.uniform1f(clipDistanceId, clipDistance)

enablePickModeId = gl.getUniformLocation(program, "enablePickMode")
gl.uniform1i(enablePickModeId, if (enablePickMode) 1 else 0)
Expand Down Expand Up @@ -209,17 +238,24 @@ open class TriangleShaderProgram : AbstractShaderProgram() {
}

fun loadMiterLengthCutoff(miterLengthCutoff : Float) {
if (this.invMiterLengthCutoff != 1.0f / miterLengthCutoff) {
this.invMiterLengthCutoff = 1.0f / miterLengthCutoff
gl.uniform1f(invMiterLengthCutoffId, invMiterLengthCutoff)
if (this.miterLengthCutoff != miterLengthCutoff) {
this.miterLengthCutoff = miterLengthCutoff
gl.uniform2f(miterLengthCutoffId, miterLengthCutoff, 1f / miterLengthCutoff)
}
}

fun loadClipDistance(clipDistance : Float) {
if (this.clipDistance != clipDistance) {
this.clipDistance = clipDistance
gl.uniform1f(clipDistanceId, clipDistance)
}
}

fun loadScreen(screenX : Float, screenY : Float) {
if ((this.screenX != screenX) and (this.screenY != screenY) ) {
this.screenX = screenX
this.screenY = screenY
gl.uniform2f(screenId, this.screenX, this.screenY)
gl.uniform4f(screenId, this.screenX, this.screenY, 1f / screenX, 1f / screenY)
}
}
}
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