commonMain.earth.worldwind.draw.DrawableStarField.kt Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of worldwind-jvm Show documentation

The WorldWind Kotlin SDK (WWK) includes the library, examples and tutorials for building multiplatform 3D virtual globe applications for Android, Web and Java.

The newest version!

package earth.worldwind.draw

import earth.worldwind.geom.Matrix4
import earth.worldwind.layer.starfield.StarFieldProgram
import earth.worldwind.render.Texture
import earth.worldwind.render.buffer.FloatBufferObject
import earth.worldwind.util.Logger
import earth.worldwind.util.Pool
import earth.worldwind.util.kgl.GL_ALIASED_POINT_SIZE_RANGE
import earth.worldwind.util.kgl.GL_FLOAT
import earth.worldwind.util.kgl.GL_POINTS
import kotlin.jvm.JvmStatic

open class DrawableStarField protected constructor(): Drawable {
    val matrix = Matrix4()
    var julianDate = 0.0
    var minMagnitude = 0.0f
    var maxMagnitude = 0.0f
    var numStars = 0
    var isShowSun = false
    var sunSize = 0.0f
    var sunTexture: Texture? = null
    var starsPositionsBuffer: FloatBufferObject? = null
    var sunPositionsBuffer: FloatBufferObject? = null
    var program: StarFieldProgram? = null
    private var pool: Pool? = null

    companion object {
        var maxGlPointSize = 0f

        @JvmStatic
        fun obtain(pool: Pool): DrawableStarField {
            val instance = pool.acquire() ?: DrawableStarField()
            instance.pool = pool
            return instance
        }
    }

    override fun recycle() {
        starsPositionsBuffer = null
        sunPositionsBuffer = null
        sunTexture = null
        program = null
        pool?.release(this)
        pool = null
    }

    override fun draw(dc: DrawContext) {
        val program = program ?: return // program unspecified
        if (!program.useProgram(dc)) return // program failed to build
        try {
            dc.gl.depthMask(false)
            drawStars(dc, program, starsPositionsBuffer)
            if (isShowSun) drawSun(dc, program, sunPositionsBuffer, sunTexture)
        } finally {
            dc.gl.depthMask(true)
        }
    }

    protected open fun drawStars(dc: DrawContext, program: StarFieldProgram, buffer: FloatBufferObject?) {
        if (buffer?.bindBuffer(dc) != true) return
        dc.gl.vertexAttribPointer(0, 4, GL_FLOAT, false, 0, 0)
        // This subtraction does not work properly on the GPU due to precision loss. It must be done on the CPU.
        program.loadModelviewProjection(matrix)
        program.loadNumDays((julianDate - 2451545.0).toFloat())
        program.loadMagnitudeRange(minMagnitude, maxMagnitude)
        program.loadTextureEnabled(false)
        dc.gl.drawArrays(GL_POINTS, 0, numStars)
    }

    protected open fun drawSun(
        dc: DrawContext, program: StarFieldProgram, sunBuffer: FloatBufferObject?, sunTexture: Texture?
    ) {
        if (maxGlPointSize == 0f) maxGlPointSize = dc.gl.getParameterfv(GL_ALIASED_POINT_SIZE_RANGE)[1]

        if (sunSize > maxGlPointSize) {
            Logger.log(Logger.WARN, "StarFieldLayer - sunSize is to big, max size allowed is: $maxGlPointSize")
        }

        if (sunBuffer?.bindBuffer(dc) != true) return
        if (sunTexture?.bindTexture(dc) != true) return
        dc.gl.vertexAttribPointer(0, 4, GL_FLOAT, false, 0, 0)
        program.loadTextureEnabled(true)
        dc.gl.drawArrays(GL_POINTS, 0, 1)
    }
}