1 files changed, 85 insertions, 0 deletions

diff --git a/gfx/src/core/buffer.c b/gfx/src/core/buffer.c
new file mode 100644
index 0000000..3b7e4bc
--- /dev/null
+++ b/gfx/src/core/buffer.c
@@ -0,0 +1,85 @@
+#include "buffer.h"
+
+#include <gfx/core.h>
+#include <gfx_assert.h>
+
+#include <math/vec2.h>
+#include <math/vec3.h>
+#include <math/vec4.h>
+
+static size_t get_buffer_size_bytes(
+    BufferType type, const BufferDataDesc* desc) {
+  return desc->count * gfx_get_buffer_type_size_bytes(type);
+}
+
+static GLenum get_buffer_usage(BufferUsage usage) {
+  switch (usage) {
+  case BufferStatic:
+    return GL_STATIC_DRAW;
+  case BufferDynamic:
+    return GL_DYNAMIC_DRAW;
+  }
+  FAIL("Unhandled buffer usage");
+  return GL_STATIC_DRAW;
+}
+
+size_t gfx_get_buffer_type_size_bytes(BufferType type) {
+  switch (type) {
+  case BufferUntyped:
+    return 1;
+  case Buffer2d:
+    return sizeof(vec2);
+  case Buffer3d:
+    return sizeof(vec3);
+  case Buffer4d:
+    return sizeof(vec4);
+  case BufferFloat:
+    return sizeof(float);
+  case BufferU8:
+    return sizeof(uint8_t);
+  case BufferU16:
+    return sizeof(uint16_t);
+  }
+  FAIL("Unhandled buffer type");
+  return 0;
+}
+
+bool gfx_init_buffer(Buffer* buffer, const BufferDesc* desc) {
+  assert(buffer);
+
+  buffer->type       = desc->type;
+  buffer->usage      = desc->usage;
+  buffer->size_bytes = get_buffer_size_bytes(desc->type, &desc->data);
+  const GLenum usage = get_buffer_usage(desc->usage);
+
+  glGenBuffers(1, &buffer->vbo);
+  glBindBuffer(GL_ARRAY_BUFFER, buffer->vbo);
+  glBufferData(GL_ARRAY_BUFFER, buffer->size_bytes, desc->data.data, usage);
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+  ASSERT_GL;
+
+  return true;
+}
+
+void gfx_del_buffer(Buffer* buffer) {
+  assert(buffer);
+  if (buffer->vbo) {
+    glDeleteBuffers(1, &buffer->vbo);
+    buffer->vbo = 0;
+  }
+}
+
+void gfx_update_buffer(Buffer* buffer, const BufferDataDesc* desc) {
+  assert(buffer);
+  assert(desc);
+  // OpenGL allows updating static buffers, but it is not optimal for
+  // performance, so we enforce data in static buffers remain static.
+  assert(buffer->usage == BufferDynamic);
+
+  const size_t update_size_bytes = get_buffer_size_bytes(buffer->type, desc);
+  assert(update_size_bytes <= buffer->size_bytes);
+
+  glBindBuffer(GL_ARRAY_BUFFER, buffer->vbo);
+  glBufferSubData(GL_ARRAY_BUFFER, 0, update_size_bytes, desc->data);
+  glBindBuffer(GL_ARRAY_BUFFER, 0);
+}