Add vertex buffer

1 files changed, 111 insertions, 0 deletions

diff --git a/src/graphics/vertex_buffer.c b/src/graphics/vertex_buffer.c
new file mode 100644
index 0000000..415f574
--- /dev/null
+++ b/src/graphics/vertex_buffer.c
@@ -0,0 +1,111 @@
+#include "../../include/mgl/graphics/vertex_buffer.h"
+#include "../../include/mgl/graphics/texture.h"
+#include "../../include/mgl/mgl.h"
+
+/* TODO: Cache vertex buffer */
+/*
+    TODO: Add option to only use vertices and color or vertices and texture coordinates.
+    In such cases we should call glEnableClientState/glDisableClientState(GL_COLOR_ARRAY/GL_TEXTURE_COORD_ARRAY) and others.
+*/
+
+static unsigned int mgl_vertex_buffer_usage_to_gl_usage(mgl_vertex_buffer_usage usage) {
+    switch(usage) {
+        case MGL_USAGE_STREAM:  return GL_STREAM_DRAW;
+        case MGL_USAGE_DYNAMIC: return GL_DYNAMIC_DRAW;
+        case MGL_USAGE_STATIC:  return GL_STATIC_DRAW;
+    }
+    return GL_STREAM_DRAW;
+}
+
+static unsigned int mgl_primitive_type_to_gl_mode(mgl_primitive_type primitive_type) {
+    switch(primitive_type) {
+        case MGL_PRIMITIVE_POINTS:          return GL_POINTS;
+        case MGL_PRIMITIVE_LINES:           return GL_LINES;
+        case MGL_PRIMITIVE_LINE_STRIP:      return GL_LINE_STRIP;
+        case MGL_PRIMITIVE_TRIANGLES:       return GL_TRIANGLES;
+        case MGL_PRIMITIVE_TRIANGLE_STRIP:  return GL_TRIANGLE_STRIP;
+        case MGL_PRIMITIVE_TRIANGLE_FAN:    return GL_TRIANGLE_FAN;
+        case MGL_PRIMITIVE_QUADS:           return GL_QUADS;
+        case MGL_PRIMITIVE_QUAD_STRIP:      return GL_QUAD_STRIP;
+        case MGL_PRIMITIVE_POLYGON:         return GL_POLYGON;
+    }
+    return MGL_PRIMITIVE_QUADS;
+}
+
+int mgl_vertex_buffer_init(mgl_vertex_buffer *self, mgl_primitive_type primitive_type, mgl_vertex_buffer_usage usage) {
+    self->id = 0;
+    self->vertex_count = 0;
+    self->primitive_type = primitive_type;
+    self->usage = usage;
+    self->position = (mgl_vec2f){ 0.0f, 0.0f };
+
+    mgl_context *context = mgl_get_context();
+    context->gl.glGenBuffers(1, &self->id);
+    if(self->id == 0)
+        return -1;
+
+    return 0;
+}
+
+void mgl_vertex_buffer_deinit(mgl_vertex_buffer *self) {
+    mgl_context *context = mgl_get_context();
+    if(self->id) {
+        context->gl.glDeleteBuffers(1, &self->id);
+        self->id = 0;
+    }
+    self->vertex_count = 0;
+    self->primitive_type = 0;
+    self->usage = 0;
+}
+
+static void mgl_vertex_buffer_set_gl_buffer_pointers(mgl_context *context) {
+    context->gl.glVertexPointer(2, GL_FLOAT, sizeof(mgl_vertex), (void*)offsetof(mgl_vertex, position));
+    context->gl.glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(mgl_vertex), (void*)offsetof(mgl_vertex, color));
+    context->gl.glTexCoordPointer(2, GL_FLOAT, sizeof(mgl_vertex), (void*)offsetof(mgl_vertex, texcoords));
+}
+
+/* TODO: Check for glBufferData error */
+static int mgl_vertex_buffer_resize(mgl_vertex_buffer *self, mgl_vertex *vertices, size_t vertex_count) {
+    mgl_context *context = mgl_get_context();
+    context->gl.glBindBuffer(GL_ARRAY_BUFFER, self->id);
+    context->gl.glBufferData(GL_ARRAY_BUFFER, sizeof(mgl_vertex) * vertex_count, vertices, mgl_vertex_buffer_usage_to_gl_usage(self->usage));
+    mgl_vertex_buffer_set_gl_buffer_pointers(context);
+    context->gl.glBindBuffer(GL_ARRAY_BUFFER, 0);
+    self->vertex_count = vertex_count;
+    return 0;
+}
+
+void mgl_vertex_buffer_set_position(mgl_vertex_buffer *self, mgl_vec2f position) {
+    self->position = position;
+}
+
+/* TODO: Check for glBufferSubData error */
+int mgl_vertex_buffer_update(mgl_vertex_buffer *self, mgl_vertex *vertices, size_t vertex_count) {
+    if(vertex_count != self->vertex_count)
+        return mgl_vertex_buffer_resize(self, vertices, vertex_count);
+
+    mgl_context *context = mgl_get_context();
+    context->gl.glBindBuffer(GL_ARRAY_BUFFER, self->id);
+    context->gl.glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(mgl_vertex) * vertex_count, vertices);
+    mgl_vertex_buffer_set_gl_buffer_pointers(context);
+    context->gl.glBindBuffer(GL_ARRAY_BUFFER, 0);
+    return 0;
+}
+
+/* TODO: Optimize bind texture */
+void mgl_vertex_buffer_draw(mgl_context *context, mgl_vertex_buffer *self, mgl_texture *texture) {
+    if(self->vertex_count == 0 || self->id == 0)
+        return;
+
+    /* TODO: Optimize this */
+    context->gl.glPushMatrix();
+    context->gl.glTranslatef(self->position.x, self->position.y, 0.0f);
+
+    context->gl.glBindTexture(GL_TEXTURE_2D, texture ? texture->id : 0);
+    context->gl.glBindBuffer(GL_ARRAY_BUFFER, self->id);
+    context->gl.glDrawArrays(mgl_primitive_type_to_gl_mode(self->primitive_type), 0, self->vertex_count);
+    context->gl.glBindBuffer(GL_ARRAY_BUFFER, 0);
+    context->gl.glBindTexture(GL_TEXTURE_2D, 0);
+
+    context->gl.glPopMatrix();
+}