commonMain.earth.worldwind.layer.atmosphere.AbstractAtmosphereProgram.kt Maven / Gradle / Ivy
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The WorldWind Kotlin SDK (WWK) includes the library, examples and tutorials for building multiplatform 3D virtual globe applications for Android, Web and Java.
package earth.worldwind.layer.atmosphere
import earth.worldwind.draw.DrawContext
import earth.worldwind.geom.Matrix3
import earth.worldwind.geom.Matrix4
import earth.worldwind.geom.Vec3
import earth.worldwind.render.program.AbstractShaderProgram
import earth.worldwind.util.kgl.KglUniformLocation
import kotlin.math.PI
import kotlin.math.pow
// TODO Correctly compute the atmosphere color for eye positions beneath the atmosphere
// TODO Test the effect of working in local coordinates (reference point) on the GLSL atmosphere programs
abstract class AbstractAtmosphereProgram: AbstractShaderProgram() {
protected var fragModeId = KglUniformLocation.NONE
protected var mvpMatrixId = KglUniformLocation.NONE
protected var texCoordMatrixId = KglUniformLocation.NONE
protected var texSamplerId = KglUniformLocation.NONE
protected var vertexOriginId = KglUniformLocation.NONE
protected var eyePointId = KglUniformLocation.NONE
protected var eyeMagnitudeId = KglUniformLocation.NONE
protected var eyeMagnitude2Id = KglUniformLocation.NONE
protected var lightDirectionId = KglUniformLocation.NONE
protected var invWavelengthId = KglUniformLocation.NONE
protected var atmosphereRadiusId = KglUniformLocation.NONE
protected var atmosphereRadius2Id = KglUniformLocation.NONE
protected var globeRadiusId = KglUniformLocation.NONE
protected var krESunId = KglUniformLocation.NONE
protected var kmESunId = KglUniformLocation.NONE
protected var kr4PIId = KglUniformLocation.NONE
protected var km4PIId = KglUniformLocation.NONE
protected var scaleId = KglUniformLocation.NONE
protected var scaleDepthId = KglUniformLocation.NONE
protected var scaleOverScaleDepthId = KglUniformLocation.NONE
protected var gId = KglUniformLocation.NONE
protected var g2Id = KglUniformLocation.NONE
protected var exposureId = KglUniformLocation.NONE
private val array = FloatArray(16)
/**
* Frag color indicates the atmospheric scattering color components written to the fragment color. Accepted values
* are [FRAGMODE_PRIMARY], [FRAGMODE_SECONDARY] and [FRAGMODE_PRIMARY_TEX_BLEND].
*/
enum class FragMode(val asInt : Int) {
PRIMARY(1),
SECONDARY(2),
PRIMARY_TEX_BLEND(3)
}
override fun initProgram(dc: DrawContext) {
super.initProgram(dc)
val invWavelength = Vec3(
1 / 0.650.pow(4.0), // 650 nm for red
1 / 0.570.pow(4.0), // 570 nm for green
1 / 0.475.pow(4.0) // 475 nm for blue
)
val kr = 0.0025 // Rayleigh scattering constant
val km = 0.0010 // Mie scattering constant
val eSun = 20.0 // Sun brightness constant
val g = -0.990 // The Mie phase asymmetry factor
val exposure = 2.0
fragModeId = gl.getUniformLocation(program, "fragMode")
gl.uniform1i(fragModeId, FragMode.PRIMARY.asInt)
mvpMatrixId = gl.getUniformLocation(program, "mvpMatrix")
Matrix4().transposeToArray(array, 0) // 4 x 4 identity matrix
gl.uniformMatrix4fv(mvpMatrixId, 1, false, array, 0)
texCoordMatrixId = gl.getUniformLocation(program, "texCoordMatrix")
Matrix3().transposeToArray(array, 0) // 3 x 3 identity matrix
gl.uniformMatrix3fv(texCoordMatrixId, 1, false, array, 0)
texSamplerId = gl.getUniformLocation(program, "texSampler")
gl.uniform1i(texSamplerId, 0) // GL_TEXTURE0
vertexOriginId = gl.getUniformLocation(program, "vertexOrigin")
array.fill(0f)
gl.uniform3fv(vertexOriginId, 1, array, 0)
eyePointId = gl.getUniformLocation(program, "eyePoint")
array.fill(0f)
gl.uniform3fv(eyePointId, 1, array, 0)
eyeMagnitudeId = gl.getUniformLocation(program, "eyeMagnitude")
gl.uniform1f(eyeMagnitudeId, 0f)
eyeMagnitude2Id = gl.getUniformLocation(program, "eyeMagnitude2")
gl.uniform1f(eyeMagnitude2Id, 0f)
lightDirectionId = gl.getUniformLocation(program, "lightDirection")
array.fill(0f)
gl.uniform3fv(lightDirectionId, 1, array, 0)
invWavelengthId = gl.getUniformLocation(program, "invWavelength")
invWavelength.toArray(array, 0)
gl.uniform3fv(invWavelengthId, 1, array, 0)
atmosphereRadiusId = gl.getUniformLocation(program, "atmosphereRadius")
atmosphereRadius2Id = gl.getUniformLocation(program, "atmosphereRadius2")
globeRadiusId = gl.getUniformLocation(program, "globeRadius")
krESunId = gl.getUniformLocation(program, "KrESun")
gl.uniform1f(krESunId, (kr * eSun).toFloat())
kmESunId = gl.getUniformLocation(program, "KmESun")
gl.uniform1f(kmESunId, (km * eSun).toFloat())
kr4PIId = gl.getUniformLocation(program, "Kr4PI")
gl.uniform1f(kr4PIId, (kr * 4 * PI).toFloat())
km4PIId = gl.getUniformLocation(program, "Km4PI")
gl.uniform1f(km4PIId, (km * 4 * PI).toFloat())
scaleId = gl.getUniformLocation(program, "scale")
scaleDepthId = gl.getUniformLocation(program, "scaleDepth")
scaleOverScaleDepthId = gl.getUniformLocation(program, "scaleOverScaleDepth")
gId = gl.getUniformLocation(program, "g")
gl.uniform1f(gId, g.toFloat())
g2Id = gl.getUniformLocation(program, "g2")
gl.uniform1f(g2Id, (g * g).toFloat())
exposureId = gl.getUniformLocation(program, "exposure")
gl.uniform1f(exposureId, exposure.toFloat())
}
fun loadFragMode(fragMode: FragMode) { gl.uniform1i(fragModeId, fragMode.asInt) }
fun loadModelviewProjection(matrix: Matrix4) {
matrix.transposeToArray(array, 0)
gl.uniformMatrix4fv(mvpMatrixId, 1, false, array, 0)
}
fun loadTexCoordMatrix(matrix: Matrix3) {
matrix.transposeToArray(array, 0)
gl.uniformMatrix3fv(texCoordMatrixId, 1, false, array, 0)
}
fun loadVertexOrigin(origin: Vec3) {
origin.toArray(array, 0)
gl.uniform3fv(vertexOriginId, 1, array, 0)
}
fun loadVertexOrigin(x: Double, y: Double, z: Double) {
gl.uniform3f(vertexOriginId, x.toFloat(), y.toFloat(), z.toFloat())
}
fun loadLightDirection(direction: Vec3) {
direction.toArray(array, 0)
gl.uniform3fv(lightDirectionId, 1, array, 0)
}
fun loadEyePoint(eyePoint: Vec3) {
eyePoint.toArray(array, 0)
gl.uniform3fv(eyePointId, 1, array, 0)
gl.uniform1f(eyeMagnitudeId, eyePoint.magnitude.toFloat())
gl.uniform1f(eyeMagnitude2Id, eyePoint.magnitudeSquared.toFloat())
}
fun loadAtmosphereParams(equatorialRadius: Double, atmosphereAltitude: Double) {
val rayleighScaleDepth = 0.25
val ar = equatorialRadius + atmosphereAltitude
gl.uniform1f(globeRadiusId, equatorialRadius.toFloat())
gl.uniform1f(atmosphereRadiusId, ar.toFloat())
gl.uniform1f(atmosphereRadius2Id, (ar * ar).toFloat())
gl.uniform1f(scaleId, (1 / atmosphereAltitude).toFloat())
gl.uniform1f(scaleDepthId, rayleighScaleDepth.toFloat())
gl.uniform1f(scaleOverScaleDepthId, (1 / atmosphereAltitude / rayleighScaleDepth).toFloat())
}
}