Make PBO speedier

[clouds.git] / clouds.cpp

diff --git a/clouds.cpp b/clouds.cpp
index f0f3a957576d17da6fdf5b60c521174e060eaeec..5787181c79fbac832a0984d362a654eaaa6ae619 100644 (file)
--- a/clouds.cpp
+++ b/clouds.cpp
@@ -63,7 +63,8 @@ void precalculateBillboardTextures() {
         float r = distance(vec2(i, j), vec2(16, 16)) / 16;
         float density = (float)d / NQ;
         data[i + j * 32] =
-            1 - fmin(1, (3 * density * (metaballField(r) / normalizationFactor)));
+            1 -
+            fmin(1, (3 * density * (metaballField(r) / normalizationFactor)));
       }
     }
 
@@ -166,14 +167,19 @@ mat4 faceView(mat4 m) {
 const int shadeWidth = 256, shadeHeight = 256;
 
 #ifdef PBO
-const int numPbos = 64;
+const int numPbos = 512;
 GLuint pboBufs[numPbos];
+GLuint pboOffsets[numPbos]; // offsets into GL_PIXEL_PACK_BUFFER that
+                            // mapPixelRead should read from
 GLbyte sink[shadeWidth * shadeHeight * 4];
 
 void inline mapPixelRead(int pboBuf, int metaball) {
   glBindBuffer(GL_PIXEL_PACK_BUFFER, pboBufs[pboBuf]);
-      GLubyte *src = (GLubyte *)glMapBufferRange(GL_PIXEL_PACK_BUFFER, 0, 4 * sizeof(GLubyte),
-          GL_MAP_READ_BIT);
+  GLubyte *src =
+      (GLubyte *)glMapBufferRange(GL_PIXEL_PACK_BUFFER, 0,
+                                  4 * sizeof(GLubyte), GL_MAP_READ_BIT);
+      /* (GLubyte *)glMapBufferRange(GL_PIXEL_PACK_BUFFER, pboOffsets[pboBuf], */
+      /*                             4 * sizeof(GLubyte), GL_MAP_READ_BIT); */
   vec4 pixel = vec4(src[0], src[1], src[2], src[3]) / vec4(255.f);
   glUnmapBuffer(GL_PIXEL_PACK_BUFFER);
 
@@ -263,11 +269,15 @@ void shadeClouds() {
 #else
 
     glBindBuffer(GL_PIXEL_PACK_BUFFER, pboBufs[pboIdx]);
-    glReadPixels(screenPos.x, screenPos.y, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE,
-                 NULL);
-    // TODO: use this
+    // It would be nice if this worked. But it doesn't
+    // macOS driver does this synchronously
+    /* glReadPixels(screenPos.x, screenPos.y, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE,
+     */
+    /*              NULL); */
     /* glReadPixels(0, 0, shadeWidth, shadeHeight, GL_RGBA, GL_UNSIGNED_BYTE, */
     /*              NULL); */
+    glReadPixels(screenPos.x, screenPos.y, 64, 64, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+    /* pboOffsets[pboIdx] = screenPos.x * 4 + screenPos.y * shadeWidth * 4; */
 
     int nextPbo = (pboIdx + 1) % numPbos;
     if (i >= numPbos - 1) {
@@ -542,7 +552,7 @@ int main(int argc, char **argv) {
   glGenBuffers(numPbos, pboBufs);
   for (int i = 0; i < numPbos; i++) {
     glBindBuffer(GL_PIXEL_PACK_BUFFER, pboBufs[i]);
-    glBufferData(GL_PIXEL_PACK_BUFFER, shadeWidth * shadeHeight * 4, NULL,
+    glBufferData(GL_PIXEL_PACK_BUFFER, 64 * 64 * 4, NULL,
                  GL_DYNAMIC_READ);
   }
   glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);