better pbo

Author: emyfops

common/src/main/kotlin/com/lambda/graphics/buffer/pbo/PixelBuffer.kt

@@ -1,8 +1,9 @@
 package com.lambda.graphics.buffer.pbo
 
+import com.lambda.Lambda.LOG
 import com.lambda.graphics.buffer.BufferUsage
+import org.lwjgl.opengl.GL
 import org.lwjgl.opengl.GL45C.*
-import org.lwjgl.opengl.GREMEDYStringMarker
 import java.nio.ByteBuffer
 
 class PixelBuffer(
@@ -17,24 +18,51 @@ class PixelBuffer(
 
     private val queryId = glGenQueries() // Used to measure the time taken to upload data to the PBO
     val uploadTime get() = IntArray(1).also { glGetQueryObjectiv(queryId, GL_QUERY_RESULT, it) }[0]
+    var transferRate = 0L // The transfer rate in bytes per second
+        private set
+
+    var pboSupported = false
+        private set
 
     fun mapTexture(id: Int, buffer: ByteBuffer) =
         upload(buffer) {
             // Bind the texture
             glBindTexture(GL_TEXTURE_2D, id)
 
-            // Perform the actual data transfer to the GPU
-            glTextureSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, 0)
+            if (buffers > 0 && pboSupported) {
+                // Bind the next PBO to update pixel values
+                glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pboIds[writeIdx])
+
+                // Perform the actual data transfer to the GPU
+                glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, 0)
+            }
+            else {
+                // Perform the actual data transfer to the GPU
+                glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer)
+            }
         }
 
     fun upload(data: ByteBuffer, process: () -> Unit) =
         recordTransfer {
-            uploadIdx = (writeIdx + 1) % buffers
+            if (buffers >= 2)
+                uploadIdx = (writeIdx + 1) % buffers
 
-            GREMEDYStringMarker.glStringMarkerGREMEDY("Data transfer to buffer")
+            // Copy the pixel values from the PBO to the texture
+            process()
 
-            // Bind the next PBO to update pixel values
-            glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pboIds[writeIdx])
+            if (!pboSupported) return@recordTransfer
+
+            // Bind the current PBO for writing
+            glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pboIds[uploadIdx])
+
+            // Note that glMapBuffer() causes sync issue.
+            // If GPU is working with this buffer, glMapBuffer() will wait(stall)
+            // until GPU to finish its job. To avoid waiting (idle), you can call
+            // first glBufferData() with NULL pointer before glMapBuffer().
+            // If you do that, the previous data in PBO will be discarded and
+            // glMapBuffer() returns a new allocated pointer immediately
+            // even if GPU is still working with the previous data.
+            glBufferData(GL_PIXEL_UNPACK_BUFFER, width * height * 4L, bufferUsage.gl)
 
             // Map the buffer into the memory
             val bufferData = glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY)
@@ -43,17 +71,7 @@ class PixelBuffer(
 
                 // Release the buffer
                 glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER)
-            } else {
-                println("Failed to map the PBO")
-            }
-
-            // Bind the current PBO for writing
-            glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pboIds[uploadIdx])
-
-            GREMEDYStringMarker.glStringMarkerGREMEDY("Data transfer to GPU")
-
-            // Copy the pixel values from the PBO to the texture
-            process()
+            } else throw IllegalStateException("Failed to map the buffer")
 
             // Unbind the PBO
             glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0)
@@ -63,6 +81,11 @@ class PixelBuffer(
         }
 
     private fun recordTransfer(block: () -> Unit) {
+        if (!pboSupported) {
+            block()
+            return
+        }
+
         // Start the timer
         glBeginQuery(GL_TIME_ELAPSED, queryId)
 
@@ -71,6 +94,12 @@ class PixelBuffer(
 
         // Stop the timer
         glEndQuery(GL_TIME_ELAPSED)
+
+        // Calculate the transfer rate
+        val time = uploadTime
+        if (time > 0) {
+            transferRate = (width * height * 4L * 1_000_000_000) / time
+        }
     }
 
     // Called when no references to the object exist
@@ -80,7 +109,13 @@ class PixelBuffer(
     }
 
     init {
-        if (buffers < 1) throw IllegalArgumentException("Buffers must be greater than or equal to 1")
+        // Check if the PBO is supported
+        GL.getCapabilities().let { pboSupported = it.OpenGL30 || it.GL_ARB_pixel_buffer_object }
+
+        if (!pboSupported && buffers > 0)
+            LOG.warn("Client tried to utilize PBOs, but they are not supported on the machine, falling back to direct buffer upload")
+
+        if (buffers < 0) throw IllegalArgumentException("Buffers must be greater than or equal to 0")
 
         // Generate the PBOs
         glGenBuffers(pboIds)