Join the python modules `gpu` and `_gpu` into one.

Maybe it's still early to set the new drawing api for python.
But joining these two modules is an initial step.

```
>>> gpu.
        matrix
        select
        types
```
```
>>> gpu.types.GPU
                 Batch(
                 OffScreen(
                 VertBuf(
                 VertFormat(
```
The creation of a new offscreen object is now done by the `GPUOffscreen.__new__` method.

Reviewers: campbellbarton, dfelinto

Reviewed By: campbellbarton, dfelinto

Tags: #bf_blender_2.8

Differential Revision: https://developer.blender.org/D3667

1 files changed, 345 insertions, 0 deletions

diff --git a/source/blender/python/gpu/gpu_py_vertex_buffer.c b/source/blender/python/gpu/gpu_py_vertex_buffer.c
new file mode 100644
index 00000000000..cc67afa4342
--- /dev/null
+++ b/source/blender/python/gpu/gpu_py_vertex_buffer.c
@@ -0,0 +1,345 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/python/gpu/gpu_py_vertex_buffer.c
+ *  \ingroup bpygpu
+ *
+ * - Use ``bpygpu_`` for local API.
+ * - Use ``BPyGPU`` for public API.
+ */
+
+#include <Python.h>
+
+#include "GPU_vertex_buffer.h"
+
+#include "BLI_math.h"
+
+#include "MEM_guardedalloc.h"
+
+#include "../generic/py_capi_utils.h"
+#include "../generic/python_utildefines.h"
+
+#include "gpu_py_vertex_format.h"
+#include "gpu_py_vertex_buffer.h" /* own include */
+
+/* -------------------------------------------------------------------- */
+
+/** \name Enum Conversion
+ *
+ * Use with PyArg_ParseTuple's "O&" formatting.
+ * \{ */
+
+static int bpygpu_ParseVertFetchMode(PyObject *o, void *p)
+{
+	Py_ssize_t mode_id_len;
+	const char *mode_id = _PyUnicode_AsStringAndSize(o, &mode_id_len);
+	if (mode_id == NULL) {
+		PyErr_Format(PyExc_ValueError,
+		             "expected a string, got %s",
+		             Py_TYPE(o)->tp_name);
+		return 0;
+	}
+#define MATCH_ID(id) \
+	if (mode_id_len == strlen(STRINGIFY(id))) { \
+		if (STREQ(mode_id, STRINGIFY(id))) { \
+			mode = GPU_FETCH_##id; \
+			goto success; \
+		} \
+	} ((void)0)
+
+	GPUVertFetchMode mode;
+	MATCH_ID(FLOAT);
+	MATCH_ID(INT);
+	MATCH_ID(INT_TO_FLOAT_UNIT);
+	MATCH_ID(INT_TO_FLOAT);
+#undef MATCH_ID
+	PyErr_Format(PyExc_ValueError,
+	             "unknown type literal: '%s'",
+	             mode_id);
+	return 0;
+
+success:
+	(*(GPUVertFetchMode *)p) = mode;
+	return 1;
+}
+
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Utility Functions
+ * \{ */
+
+#define PY_AS_NATIVE_SWITCH(attr) \
+	switch (attr->comp_type) { \
+		case GPU_COMP_I8:  { PY_AS_NATIVE(int8_t,   PyC_Long_AsI8); break; } \
+		case GPU_COMP_U8:  { PY_AS_NATIVE(uint8_t,  PyC_Long_AsU8); break; } \
+		case GPU_COMP_I16: { PY_AS_NATIVE(int16_t,  PyC_Long_AsI16); break; } \
+		case GPU_COMP_U16: { PY_AS_NATIVE(uint16_t, PyC_Long_AsU16); break; } \
+		case GPU_COMP_I32: { PY_AS_NATIVE(int32_t,  PyC_Long_AsI32); break; } \
+		case GPU_COMP_U32: { PY_AS_NATIVE(uint32_t, PyC_Long_AsU32); break; } \
+		case GPU_COMP_F32: { PY_AS_NATIVE(float, PyFloat_AsDouble); break; } \
+		default: \
+			BLI_assert(0); \
+	} ((void)0)
+
+/* No error checking, callers must run PyErr_Occurred */
+static void fill_format_elem(void *data_dst_void, PyObject *py_src, const GPUVertAttr *attr)
+{
+#define PY_AS_NATIVE(ty_dst, py_as_native) \
+{ \
+	ty_dst *data_dst = data_dst_void; \
+	*data_dst = py_as_native(py_src); \
+} ((void)0)
+
+	PY_AS_NATIVE_SWITCH(attr);
+
+#undef PY_AS_NATIVE
+}
+
+/* No error checking, callers must run PyErr_Occurred */
+static void fill_format_tuple(void *data_dst_void, PyObject *py_src, const GPUVertAttr *attr)
+{
+	const uint len = attr->comp_len;
+
+/**
+ * Args are constants, so range checks will be optimized out if they're nop's.
+ */
+#define PY_AS_NATIVE(ty_dst, py_as_native) \
+	ty_dst *data_dst = data_dst_void; \
+	for (uint i = 0; i < len; i++) { \
+		data_dst[i] = py_as_native(PyTuple_GET_ITEM(py_src, i)); \
+	} ((void)0)
+
+	PY_AS_NATIVE_SWITCH(attr);
+
+#undef PY_AS_NATIVE
+}
+
+#undef PY_AS_NATIVE_SWITCH
+#undef WARN_TYPE_LIMIT_PUSH
+#undef WARN_TYPE_LIMIT_POP
+
+static bool bpygpu_vertbuf_fill_impl(
+        GPUVertBuf *vbo,
+        uint data_id, PyObject *seq)
+{
+	bool ok = true;
+	const GPUVertAttr *attr = &vbo->format.attribs[data_id];
+
+	GPUVertBufRaw data_step;
+	GPU_vertbuf_attr_get_raw_data(vbo, data_id, &data_step);
+
+	PyObject *seq_fast = PySequence_Fast(seq, "Vertex buffer fill");
+	if (seq_fast == NULL) {
+		goto finally;
+	}
+
+	const uint seq_len = PySequence_Fast_GET_SIZE(seq_fast);
+
+	if (seq_len != vbo->vertex_len) {
+		PyErr_Format(PyExc_ValueError,
+		             "Expected a sequence of size %d, got %d",
+		             vbo->vertex_len, seq_len);
+	}
+
+	PyObject **seq_items = PySequence_Fast_ITEMS(seq_fast);
+
+	if (attr->comp_len == 1) {
+		for (uint i = 0; i < seq_len; i++) {
+			uchar *data = (uchar *)GPU_vertbuf_raw_step(&data_step);
+			PyObject *item = seq_items[i];
+			fill_format_elem(data, item, attr);
+		}
+	}
+	else {
+		for (uint i = 0; i < seq_len; i++) {
+			uchar *data = (uchar *)GPU_vertbuf_raw_step(&data_step);
+			PyObject *item = seq_items[i];
+			if (!PyTuple_CheckExact(item)) {
+				PyErr_Format(PyExc_ValueError,
+				             "expected a tuple, got %s",
+				             Py_TYPE(item)->tp_name);
+				ok = false;
+				goto finally;
+			}
+			if (PyTuple_GET_SIZE(item) != attr->comp_len) {
+				PyErr_Format(PyExc_ValueError,
+				             "expected a tuple of size %d, got %d",
+				             attr->comp_len, PyTuple_GET_SIZE(item));
+				ok = false;
+				goto finally;
+			}
+
+			/* May trigger error, check below */
+			fill_format_tuple(data, item, attr);
+		}
+	}
+
+	if (PyErr_Occurred()) {
+		ok = false;
+	}
+
+finally:
+
+	Py_DECREF(seq_fast);
+	return ok;
+}
+
+/* handy, but not used just now */
+#if 0
+static int bpygpu_find_id(const GPUVertFormat *fmt, const char *id)
+{
+	for (int i = 0; i < fmt->attr_len; i++) {
+		for (uint j = 0; j < fmt->name_len; j++) {
+			if (STREQ(fmt->attribs[i].name[j], id)) {
+				return i;
+			}
+		}
+	}
+	return -1;
+}
+#endif
+
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name VertBuf Type
+ * \{ */
+
+static PyObject *bpygpu_VertBuf_new(PyTypeObject *UNUSED(type), PyObject *args, PyObject *kwds)
+{
+	const char * const keywords[] = {"len", "format", NULL};
+
+	struct {
+		BPyGPUVertFormat *py_fmt;
+		uint len;
+	} params;
+
+	if (!PyArg_ParseTupleAndKeywords(
+	        args, kwds,
+	        "$IO!:GPUVertBuf.__new__", (char **)keywords,
+	        &params.len,
+	        &BPyGPUVertFormat_Type, &params.py_fmt))
+	{
+		return NULL;
+	}
+
+	struct GPUVertBuf *vbo = GPU_vertbuf_create_with_format(&params.py_fmt->fmt);
+
+	GPU_vertbuf_data_alloc(vbo, params.len);
+
+	return BPyGPUVertBuf_CreatePyObject(vbo);
+}
+
+PyDoc_STRVAR(bpygpu_VertBuf_fill_doc,
+"TODO"
+);
+static PyObject *bpygpu_VertBuf_fill(BPyGPUVertBuf *self, PyObject *args, PyObject *kwds)
+{
+	static const char *kwlist[] = {"id", "data", NULL};
+
+	struct {
+		uint id;
+		PyObject *py_seq_data;
+	} params;
+
+	if (!PyArg_ParseTupleAndKeywords(
+	        args, kwds, "$IO:fill", (char **)kwlist,
+	        &params.id,
+	        &params.py_seq_data))
+	{
+		return NULL;
+	}
+
+	if (params.id >= self->buf->format.attr_len) {
+		PyErr_Format(PyExc_ValueError,
+		             "Format id %d out of range",
+		             params.id);
+		return NULL;
+	}
+
+	if (self->buf->data == NULL) {
+		PyErr_SetString(PyExc_ValueError,
+		                "Can't fill, static buffer already in use");
+		return NULL;
+	}
+
+	if (!bpygpu_vertbuf_fill_impl(self->buf, params.id, params.py_seq_data)) {
+		return NULL;
+	}
+	Py_RETURN_NONE;
+}
+
+static struct PyMethodDef bpygpu_VertBuf_methods[] = {
+	{"fill", (PyCFunction) bpygpu_VertBuf_fill,
+	 METH_VARARGS | METH_KEYWORDS, bpygpu_VertBuf_fill_doc},
+	{NULL, NULL, 0, NULL}
+};
+
+static void bpygpu_VertBuf_dealloc(BPyGPUVertBuf *self)
+{
+	GPU_vertbuf_discard(self->buf);
+	Py_TYPE(self)->tp_free(self);
+}
+
+PyDoc_STRVAR(py_gpu_vertex_buffer_doc,
+"GPUVertBuf(len, format)\n"
+"\n"
+"Contains a VBO."
+"\n"
+"   :param len: number of elements to allocate\n"
+"   :type type: int`\n"
+"   :param format: Vertex format.\n"
+"   :type buf: GPUVertFormat`\n"
+);
+PyTypeObject BPyGPUVertBuf_Type = {
+	PyVarObject_HEAD_INIT(NULL, 0)
+	.tp_name = "GPUVertBuf",
+	.tp_basicsize = sizeof(BPyGPUVertBuf),
+	.tp_dealloc = (destructor)bpygpu_VertBuf_dealloc,
+	.tp_flags = Py_TPFLAGS_DEFAULT,
+	.tp_doc = py_gpu_vertex_buffer_doc,
+	.tp_methods = bpygpu_VertBuf_methods,
+	.tp_new = bpygpu_VertBuf_new,
+};
+
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Public API
+ * \{ */
+
+PyObject *BPyGPUVertBuf_CreatePyObject(GPUVertBuf *buf)
+{
+	BPyGPUVertBuf *self;
+
+	self = PyObject_New(BPyGPUVertBuf, &BPyGPUVertBuf_Type);
+	self->buf = buf;
+
+	return (PyObject *)self;
+}
+
+/** \} */