commonMain.earth.worldwind.draw.DrawContext.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.draw
import earth.worldwind.PickedObjectList
import earth.worldwind.geom.Matrix4
import earth.worldwind.geom.Vec2
import earth.worldwind.geom.Vec3
import earth.worldwind.geom.Viewport
import earth.worldwind.render.Color
import earth.worldwind.render.Framebuffer
import earth.worldwind.render.Texture
import earth.worldwind.render.buffer.BufferPool
import earth.worldwind.render.buffer.FloatBufferObject
import earth.worldwind.render.buffer.IntBufferObject
import earth.worldwind.util.kgl.*
open class DrawContext(val gl: Kgl) {
val eyePoint = Vec3()
val viewport = Viewport()
val projection = Matrix4()
val modelview = Matrix4()
val modelviewProjection = Matrix4()
// val infiniteProjection = Matrix4()
val screenProjection = Matrix4()
var drawableQueue: DrawableQueue? = null
var drawableTerrain: DrawableQueue? = null
var pickedObjects: PickedObjectList? = null
var pickViewport: Viewport? = null
var pickPoint: Vec2? = null
var isPickMode = false
private var framebuffer = KglFramebuffer.NONE
private var program = KglProgram.NONE
private var textureUnit = GL_TEXTURE0
private val textures = Array(32) { KglTexture.NONE }
private var arrayBuffer = KglBuffer.NONE
private var elementArrayBuffer = KglBuffer.NONE
private var scratchFramebufferCache: Framebuffer? = null
private var unitSquareBufferCache: FloatBufferObject? = null
private var rectangleElementsBufferCache: IntBufferObject? = null
private var scratchBuffer = ByteArray(4)
private val pixelArray = ByteArray(4)
private var bufferPool = BufferPool(GL_ARRAY_BUFFER, GL_DYNAMIC_DRAW)
/**
* Returns count of terrain drawables in queue
*/
val drawableTerrainCount get() = drawableTerrain?.count?:0
/**
* Returns the name of the OpenGL framebuffer object that is currently active.
*/
val currentFramebuffer get() = framebuffer
/**
* Returns the name of the OpenGL program object that is currently active.
*/
val currentProgram get() = program
/**
* Returns the OpenGL multitexture unit that is currently active. Returns a value from the GL_TEXTUREi enumeration,
* where i ranges from 0 to 32.
*/
val currentTextureUnit get() = textureUnit
/**
* Returns the name of the OpenGL texture 2D object currently bound to the active multitexture unit. The active
* multitexture unit may be determined by calling currentTextureUnit.
*/
val currentTexture get() = currentTexture(textureUnit)
/**
* Returns an OpenGL framebuffer object suitable for offscreen drawing. The framebuffer has a 32-bit color buffer
* and a 32-bit depth buffer, both attached as OpenGL texture 2D objects.
*
* The framebuffer may be used by any drawable and for any purpose. However, the draw context makes no guarantees
* about the framebuffer's contents. Drawables must clear the framebuffer before use, and must assume its contents
* may be modified by another drawable, either during the current frame or in a subsequent frame.
*
* The OpenGL framebuffer object is created on first use and cached. Subsequent calls to this method return the
* cached buffer object.
*/
val scratchFramebuffer get() = scratchFramebufferCache ?: Framebuffer().apply {
val colorAttachment = Texture(1024, 1024, GL_RGBA, GL_UNSIGNED_BYTE, true)
val depthAttachment = Texture(1024, 1024, GL_DEPTH_COMPONENT, GL_UNSIGNED_SHORT, true)
// TODO consider modifying Texture's tex parameter behavior in order to make this unnecessary
depthAttachment.setTexParameter(GL_TEXTURE_MIN_FILTER, GL_NEAREST)
depthAttachment.setTexParameter(GL_TEXTURE_MAG_FILTER, GL_NEAREST)
attachTexture(this@DrawContext, colorAttachment, GL_COLOR_ATTACHMENT0)
attachTexture(this@DrawContext, depthAttachment, GL_DEPTH_ATTACHMENT)
}.also { scratchFramebufferCache = it }
/**
* Returns an OpenGL buffer object containing a unit square expressed as four vertices at (0, 1), (0, 0), (1, 1) and
* (1, 0). Each vertex is stored as two 32-bit floating point coordinates. The four vertices are in the order
* required by a triangle strip.
*
* The OpenGL buffer object is created on first use and cached. Subsequent calls to this method return the cached
* buffer object.
*/
val unitSquareBuffer get() = unitSquareBufferCache ?: FloatBufferObject(
GL_ARRAY_BUFFER, floatArrayOf(0f, 1f, 0f, 0f, 1f, 1f, 1f, 0f)
).also { unitSquareBufferCache = it }
/**
* Returns an OpenGL buffer object containing indices needed to render triangle
* Expected vertex data layout for this buffer is something like this
* 1 ---- 0
* | /|
* | / |
* | / |
* | / |
* | / |
* 3 ---- 2
*
* The OpenGL buffer object is created on first use and cached. Subsequent calls to this method return the cached
* buffer object.
*/
val rectangleElementsBuffer get() = rectangleElementsBufferCache ?: IntBufferObject(
GL_ELEMENT_ARRAY_BUFFER, intArrayOf(0, 1, 2, 2, 1, 3)
).also { rectangleElementsBufferCache = it }
/**
* Returns a scratch list suitable for accumulating entries during drawing. The list is cleared before each frame,
* otherwise its contents are undefined.
*/
val scratchList = mutableListOf()
fun reset() {
eyePoint.set(0.0, 0.0, 0.0)
viewport.setEmpty()
projection.setToIdentity()
modelview.setToIdentity()
modelviewProjection.setToIdentity()
screenProjection.setToIdentity()
// infiniteProjection.setToIdentity()
drawableQueue = null
drawableTerrain = null
pickedObjects = null
pickViewport = null
pickPoint = null
isPickMode = false
scratchBuffer.fill(0)
scratchList.clear()
bufferPool.reset()
}
fun contextLost() {
// Clear objects and values associated with the current OpenGL context.
framebuffer = KglFramebuffer.NONE
program = KglProgram.NONE
textureUnit = GL_TEXTURE0
arrayBuffer = KglBuffer.NONE
elementArrayBuffer = KglBuffer.NONE
scratchFramebufferCache = null
unitSquareBufferCache = null
rectangleElementsBufferCache = null
textures.fill(KglTexture.NONE)
bufferPool.contextLost()
}
fun peekDrawable() = drawableQueue?.peekDrawable()
fun pollDrawable() = drawableQueue?.pollDrawable()
fun rewindDrawables() { drawableQueue?.rewindDrawables() }
fun getDrawableTerrain(index: Int) = drawableTerrain?.getDrawable(index) as DrawableTerrain? ?: error("Invalid index")
/**
* Makes an OpenGL framebuffer object active. The active framebuffer becomes the target of all OpenGL commands that
* render to the framebuffer or read from the framebuffer. This has no effect if the specified framebuffer object is
* already active. The default is framebuffer 0, indicating that the default framebuffer provided by the windowing
* system is active.
*
* @param framebuffer the name of the OpenGL framebuffer object to make active, or 0 to make the default
* framebuffer provided by the windowing system active
*/
fun bindFramebuffer(framebuffer: KglFramebuffer) {
if (this.framebuffer != framebuffer) {
this.framebuffer = framebuffer
gl.bindFramebuffer(GL_FRAMEBUFFER, framebuffer)
}
}
/**
* Makes an OpenGL program object active as part of current rendering state. This has no effect if the specified
* program object is already active. The default is program 0, indicating that no program is active.
*
* @param program the name of the OpenGL program object to make active, or 0 to make no program active
*/
fun useProgram(program: KglProgram) {
if (this.program != program) {
this.program = program
gl.useProgram(program)
}
}
/**
* Specifies the OpenGL multitexture unit to make active. This has no effect if the specified multitexture unit is
* already active. The default is GL_TEXTURE0.
*
* @param textureUnit the multitexture unit, one of GL_TEXTUREi, where i ranges from 0 to 32.
*/
fun activeTextureUnit(textureUnit: Int) {
if (this.textureUnit != textureUnit) {
this.textureUnit = textureUnit
gl.activeTexture(textureUnit)
}
}
/**
* Returns the name of the OpenGL texture 2D object currently bound to the specified multitexture unit.
*
* @param textureUnit the multitexture unit, one of GL_TEXTUREi, where i ranges from 0 to 32.
*
* @return the currently bound texture 2D object, or 0 if no texture object is bound
*/
fun currentTexture(textureUnit: Int) = textures[textureUnit - GL_TEXTURE0]
/**
* Makes an OpenGL texture 2D object bound to the current multitexture unit. This has no effect if the specified
* texture object is already bound. The default is texture 0, indicating that no texture is bound.
*
* @param texture the name of the OpenGL texture 2D object to make active, or 0 to make no texture active
*/
fun bindTexture(texture: KglTexture) {
val textureUnitIndex = textureUnit - GL_TEXTURE0
if (textures[textureUnitIndex] != texture) {
textures[textureUnitIndex] = texture
gl.bindTexture(GL_TEXTURE_2D, texture)
}
}
/**
* Returns the name of the OpenGL buffer object bound to the specified target buffer.
*
* @param target the target buffer, either GL_ARRAY_BUFFER or GL_ELEMENT_ARRAY_BUFFER
*
* @return the currently bound buffer object, or 0 if no buffer object is bound
*/
fun currentBuffer(target: Int): KglBuffer {
return when (target) {
GL_ARRAY_BUFFER -> arrayBuffer
GL_ELEMENT_ARRAY_BUFFER -> elementArrayBuffer
else -> KglBuffer.NONE
}
}
/**
* Makes an OpenGL buffer object bound to a specified target buffer. This has no effect if the specified buffer
* object is already bound. The default is buffer 0, indicating that no buffer object is bound.
*
* @param target the target buffer, either GL_ARRAY_BUFFER or GL_ELEMENT_ARRAY_BUFFER
* @param buffer the name of the OpenGL buffer object to make active
*/
fun bindBuffer(target: Int, buffer: KglBuffer) {
if (target == GL_ARRAY_BUFFER && arrayBuffer != buffer) {
arrayBuffer = buffer
gl.bindBuffer(target, buffer)
} else if (target == GL_ELEMENT_ARRAY_BUFFER && elementArrayBuffer != buffer) {
elementArrayBuffer = buffer
gl.bindBuffer(target, buffer)
} else {
gl.bindBuffer(target, buffer)
}
}
/**
* Puts dynamic vertex data into the buffer pool and returns offset.
*
* @param vertexData dynamic vertex data to be added in the buffer pool
* @return offset in the buffer pool
*/
fun bindBufferPool(vertexData: FloatArray) = bufferPool.bindBuffer(this, vertexData)
/**
* Reads the fragment color at a screen point in the currently active OpenGL frame buffer. The X and Y components
* indicate OpenGL screen coordinates, which originate in the frame buffer's lower left corner.
*
* @param x the screen point's X component
* @param y the screen point's Y component
* @param result an optional pre-allocated Color in which to return the fragment color, or null to return a new
* color
*
* @return the result argument set to the fragment color, or a new color if the result is null
*/
fun readPixelColor(x: Int, y: Int, result: Color): Color {
// Read the fragment pixel as an RGBA 8888 color.
gl.readPixels(x, y, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, pixelArray)
// Convert the RGBA 8888 color to a WorldWind color.
result.red = (pixelArray[0].toInt() and 0xFF) / 0xFF.toFloat()
result.green = (pixelArray[1].toInt() and 0xFF) / 0xFF.toFloat()
result.blue = (pixelArray[2].toInt() and 0xFF) / 0xFF.toFloat()
result.alpha = (pixelArray[3].toInt() and 0xFF) / 0xFF.toFloat()
return result
}
/**
* Reads the unique fragment colors within a screen rectangle in the currently active OpenGL frame buffer. The
* components indicate OpenGL screen coordinates, which originate in the frame buffer's lower left corner.
*
* @param x the screen rectangle's X component
* @param y the screen rectangle's Y component
* @param width the screen rectangle's width
* @param height the screen rectangle's height
*
* @return a set containing the unique fragment colors
*/
fun readPixelColors(x: Int, y: Int, width: Int, height: Int): Set {
// Read the fragment pixels as a tightly packed array of RGBA 8888 colors.
val pixelCount = width * height
val pixelBuffer = scratchBuffer(pixelCount * 4)
val packAlignment = gl.getParameteri(GL_PACK_ALIGNMENT)
gl.pixelStorei(GL_PACK_ALIGNMENT, 1) // read byte aligned
gl.readPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixelBuffer)
gl.pixelStorei(GL_PACK_ALIGNMENT, packAlignment) // restore the pack alignment
val resultSet = mutableSetOf()
var result = Color()
for (i in 0 until pixelCount) {
val idx = i * 4
// Convert the RGBA 8888 color to a WorldWind color.
result.red = (pixelBuffer[idx + 0].toInt() and 0xFF) / 0xFF.toFloat()
result.green = (pixelBuffer[idx + 1].toInt() and 0xFF) / 0xFF.toFloat()
result.blue = (pixelBuffer[idx + 2].toInt() and 0xFF) / 0xFF.toFloat()
result.alpha = (pixelBuffer[idx + 3].toInt() and 0xFF) / 0xFF.toFloat()
// Accumulate the unique colors in a set.
if (resultSet.add(result)) result = Color()
}
return resultSet
}
/**
* Returns a scratch NIO buffer suitable for use during drawing. The returned buffer has capacity at least equal to
* the specified capacity. The buffer is cleared before each frame, otherwise its contents, position, limit and mark
* are undefined.
*
* @param capacity the buffer's minimum capacity in bytes
*
* @return the draw context's scratch buffer
*/
fun scratchBuffer(capacity: Int): ByteArray {
if (scratchBuffer.size < capacity) scratchBuffer = ByteArray(capacity)
return scratchBuffer
}
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