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kwin: Don't reallocate the vertex buffer on every setData() call

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Allocate enough space to hold the geometry for multiple draw calls,
and use glMapBufferRange() to gradually fill the buffer.  Once the
data store is full, it's orphaned and a new one is allocated.
This commit is contained in:
Fredrik Höglund 2012-09-11 17:49:33 +02:00
parent 0475559120
commit e1a33cec44
1 changed files with 30 additions and 14 deletions
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44
libkwineffects/kwinglutils.cpp
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@ -1186,6 +1186,7 @@ public:
, useTexCoords(true)
, color(0, 0, 0, 255)
, bufferSize(0)
, nextOffset(0)
, vertexAddress(0)
, texCoordAddress(0)
{
@ -1211,7 +1212,7 @@ public:
}
void interleaveArrays(float *array, int dim, const float *vertices, const float *texcoords, int count);
GLvoid *mapBufferRange(size_t size);
GLvoid *mapNextFreeRange(size_t size);
GLuint buffer;
GLenum usage;
@ -1227,6 +1228,7 @@ public:
bool useTexCoords;
QColor color;
size_t bufferSize;
intptr_t nextOffset;
intptr_t vertexAddress;
intptr_t texCoordAddress;
@ -1399,23 +1401,29 @@ T align(T value, int bytes)
return (value + bytes - 1) & ~T(bytes - 1);
}
GLvoid *GLVertexBufferPrivate::mapBufferRange(size_t size)
GLvoid *GLVertexBufferPrivate::mapNextFreeRange(size_t size)
{
GLbitfield access = GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_RANGE_BIT;
GLbitfield access = GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_RANGE_BIT | GL_MAP_UNSYNCHRONIZED_BIT;
if (size > bufferSize) {
if ((nextOffset + size) > bufferSize) {
// Reallocate the data store if it's too small.
// Round the size up to 4 Kb for streaming/dynamic buffers.
const size_t alloc = usage != GL_STATIC_DRAW ? align(size, 4096) : size;
glBufferData(GL_ARRAY_BUFFER, alloc, 0, usage);
bufferSize = alloc;
} else {
// Hint the GL that it may discard the whole resource if there is contention.
// This will pretty much always be the case.
access |= GL_MAP_INVALIDATE_BUFFER_BIT;
if (size > bufferSize) {
// Round the size up to 4 Kb for streaming/dynamic buffers.
const size_t minSize = 32768; // Minimum size for streaming buffers
const size_t alloc = usage != GL_STATIC_DRAW ? align(qMax(size, minSize), 4096) : size;
glBufferData(GL_ARRAY_BUFFER, alloc, 0, usage);
bufferSize = alloc;
} else {
access |= GL_MAP_INVALIDATE_BUFFER_BIT;
access ^= GL_MAP_UNSYNCHRONIZED_BIT;
}
nextOffset = 0;
}
return glMapBufferRange(GL_ARRAY_BUFFER, 0, size, access);
return glMapBufferRange(GL_ARRAY_BUFFER, nextOffset, size, access);
}
@ -1464,9 +1472,14 @@ void GLVertexBuffer::setData(int vertexCount, int dim, const float* vertices, co
glBindBuffer(GL_ARRAY_BUFFER, d->buffer);
if (d->hasMapBufferRange) {
float *map = (float *) d->mapBufferRange(size);
// Upload the data into the next free range in the buffer
float *map = (float *) d->mapNextFreeRange(size);
d->interleaveArrays(map, dim, vertices, texcoords, vertexCount);
glUnmapBuffer(GL_ARRAY_BUFFER);
d->vertexAddress = d->nextOffset;
d->texCoordAddress = d->nextOffset + d->dimension * sizeof(float);
d->nextOffset += align(size, 16); // Align to 16 bytes for SSE
} else {
// We always reallocate the data store when we can't map the buffer.
// The rationale is that there will almost always be contention
@ -1479,6 +1492,9 @@ void GLVertexBuffer::setData(int vertexCount, int dim, const float* vertices, co
glBufferData(GL_ARRAY_BUFFER, size, array.data(), d->usage);
} else
glBufferData(GL_ARRAY_BUFFER, size, vertices, d->usage);
d->vertexAddress = 0;
d->texCoordAddress = d->dimension * sizeof(float);
}
glBindBuffer(GL_ARRAY_BUFFER, 0);