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#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);
}
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