Fix multiple vertex buffers using the same data

Need to call glVertexPointer/glTexCoordPointer/glColorPointer every time
we render.

5 files changed, 51 insertions, 12 deletions

diff --git a/include/mgl/gl.h b/include/mgl/gl.h
index a13406e..c9a709d 100644
--- a/include/mgl/gl.h
+++ b/include/mgl/gl.h
@@ -67,6 +67,8 @@ typedef struct {
     void (*glAttachShader)(unsigned int program, unsigned int shader);
     int (*glGetUniformLocation)(unsigned int program, const char *name);
     void (*glUniform2fv)(int location, int count, const float *value);
+    unsigned int (*glGetError)(void);
+    const unsigned char* (*glGetString)(unsigned int name);
 
     /* Optional*/
     void (*glXSwapIntervalEXT)(Display * dpy, GLXDrawable drawable, int interval);
diff --git a/src/gl.c b/src/gl.c
index 4227d9e..c54bbbf 100644
--- a/src/gl.c
+++ b/src/gl.c
@@ -82,6 +82,8 @@ int mgl_gl_load(mgl_gl *self) {
         { &self->glAttachShader, "glAttachShader" },
         { &self->glGetUniformLocation, "glGetUniformLocation" },
         { &self->glUniform2fv, "glUniform2fv" },
+        { &self->glGetError, "glGetError" },
+        { &self->glGetString, "glGetString" },
 
         { NULL, NULL }
     };
diff --git a/src/graphics/vertex_buffer.c b/src/graphics/vertex_buffer.c
index aa4fdbb..9203d63 100644
--- a/src/graphics/vertex_buffer.c
+++ b/src/graphics/vertex_buffer.c
@@ -104,6 +104,7 @@ void mgl_vertex_buffer_draw(mgl_context *context, mgl_vertex_buffer *vertex_buff
 
     context->gl.glBindTexture(GL_TEXTURE_2D, texture ? texture->id : 0);
     context->gl.glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer->id);
+    mgl_vertex_buffer_set_gl_buffer_pointers(context);
     context->gl.glDrawArrays(mgl_primitive_type_to_gl_mode(vertex_buffer->primitive_type), 0, vertex_buffer->vertex_count);
     context->gl.glBindBuffer(GL_ARRAY_BUFFER, 0);
     context->gl.glBindTexture(GL_TEXTURE_2D, 0);
diff --git a/src/window/window.c b/src/window/window.c
index f29b920..94756cd 100644
--- a/src/window/window.c
+++ b/src/window/window.c
@@ -103,8 +103,8 @@ static int mgl_window_init(mgl_window *self, const char *title, int width, int h
     context->gl.glEnable(GL_BLEND);
     context->gl.glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     context->gl.glEnableClientState(GL_VERTEX_ARRAY);
-    context->gl.glEnableClientState(GL_COLOR_ARRAY);
     context->gl.glEnableClientState(GL_TEXTURE_COORD_ARRAY);
+    context->gl.glEnableClientState(GL_COLOR_ARRAY);
 
     XWindowAttributes gwa;
     gwa.width = 0;
diff --git a/tests/main.c b/tests/main.c
index 53134b9..98c68ad 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -14,7 +14,8 @@
 typedef struct {
     mgl_texture *texture;
     mgl_font *font;
-    mgl_vertex_buffer *vertex_buffer;
+    mgl_vertex_buffer *vertex_buffer1;
+    mgl_vertex_buffer *vertex_buffer2;
     mgl_shader_program *shader_program;
     mgl_clock clock;
 } Userdata;
@@ -47,8 +48,11 @@ static void draw(mgl_window *window, void *userdata) {
     mgl_text_draw(context, &text);
     mgl_text_deinit(&text);
 
-    mgl_vertex_buffer_set_position(u->vertex_buffer, (mgl_vec2f){ window->cursor_position.x, window->cursor_position.y });
-    mgl_vertex_buffer_draw(context, u->vertex_buffer, &u->font->texture);
+    mgl_vertex_buffer_set_position(u->vertex_buffer1, (mgl_vec2f){ window->cursor_position.x, window->cursor_position.y });
+    mgl_vertex_buffer_draw(context, u->vertex_buffer1, &u->font->texture);
+
+    mgl_vertex_buffer_set_position(u->vertex_buffer2, (mgl_vec2f){ window->cursor_position.x, window->cursor_position.y + 500 });
+    mgl_vertex_buffer_draw(context, u->vertex_buffer2, &u->font->texture);
 }
 
 int main(int argc, char **argv) {
@@ -57,13 +61,15 @@ int main(int argc, char **argv) {
 
     mgl_texture texture;
     mgl_font font;
-    mgl_vertex_buffer vertex_buffer;
+    mgl_vertex_buffer vertex_buffer1;
+    mgl_vertex_buffer vertex_buffer2;
     mgl_shader_program shader_program;
 
     Userdata userdata;
     userdata.texture = &texture;
     userdata.font = &font;
-    userdata.vertex_buffer = &vertex_buffer;
+    userdata.vertex_buffer1 = &vertex_buffer1;
+    userdata.vertex_buffer2 = &vertex_buffer2;
     userdata.shader_program = &shader_program;
     mgl_clock_init(&userdata.clock);
 
@@ -86,9 +92,10 @@ int main(int argc, char **argv) {
     if(mgl_shader_program_finalize(&shader_program) != 0)
         return 1;
 
-    mgl_vertex_buffer_init(&vertex_buffer);
+    mgl_vertex_buffer_init(&vertex_buffer1);
+    mgl_vertex_buffer_init(&vertex_buffer2);
 
-    mgl_vertex vertices[4] = {
+    mgl_vertex vertices1[4] = {
         (mgl_vertex){
             .position = {0.0f, 0.0f},
             .texcoords = {0.0f, 0.0f},
@@ -100,18 +107,44 @@ int main(int argc, char **argv) {
             .color = {0, 255, 0, 100},
         },
         (mgl_vertex){
-            .position = {font.texture.width, font.texture.height},
+            .position = {font.texture.width, font.texture.height/2},
+            .texcoords = {1.0f, 0.5f},
+            .color = {0, 0, 255, 100},
+        },
+        (mgl_vertex){
+            .position = {0.0f, font.texture.height/2},
+            .texcoords = {0.0f, 0.5f},
+            .color = {255, 0, 255, 100}
+        }
+    };
+
+    mgl_vertex vertices2[4] = {
+        (mgl_vertex){
+            .position = {0.0f, 0.0f},
+            .texcoords = {0.0f, 0.5f},
+            .color = {255, 0, 0, 100}
+        },
+        (mgl_vertex){
+            .position = {font.texture.width, 0.0f},
+            .texcoords = {1.0f, 0.5f},
+            .color = {0, 255, 0, 100},
+        },
+        (mgl_vertex){
+            .position = {font.texture.width, font.texture.height/2},
             .texcoords = {1.0f, 1.0f},
             .color = {0, 0, 255, 100},
         },
         (mgl_vertex){
-            .position = {0.0f, font.texture.height},
+            .position = {0.0f, font.texture.height/2},
             .texcoords = {0.0f, 1.0f},
             .color = {255, 0, 255, 100}
         }
     };
 
-    if(mgl_vertex_buffer_update(&vertex_buffer, vertices, 4, MGL_PRIMITIVE_QUADS, MGL_USAGE_STATIC) != 0)
+    if(mgl_vertex_buffer_update(&vertex_buffer1, vertices1, 4, MGL_PRIMITIVE_QUADS, MGL_USAGE_STATIC) != 0)
+        return 1;
+
+    if(mgl_vertex_buffer_update(&vertex_buffer2, vertices2, 4, MGL_PRIMITIVE_QUADS, MGL_USAGE_STATIC) != 0)
         return 1;
 
     fprintf(stderr, "Font texture width: %d, texture height: %d\n", font.texture.width, font.texture.height);
@@ -127,7 +160,8 @@ int main(int argc, char **argv) {
         mgl_window_display(&window);
     }
 
-    mgl_vertex_buffer_deinit(&vertex_buffer);
+    mgl_vertex_buffer_deinit(&vertex_buffer2);
+    mgl_vertex_buffer_deinit(&vertex_buffer1);
     mgl_shader_program_deinit(&shader_program);
     mgl_font_unload(&font);
     mgl_texture_unload(&texture);