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-rw-r--r--sly/render/mesh.scm69
1 files changed, 56 insertions, 13 deletions
diff --git a/sly/render/mesh.scm b/sly/render/mesh.scm
index 04a8ab2..acf9a0f 100644
--- a/sly/render/mesh.scm
+++ b/sly/render/mesh.scm
@@ -25,18 +25,21 @@
#:use-module (ice-9 format)
#:use-module (ice-9 match)
#:use-module (rnrs bytevectors)
+ #:use-module (srfi srfi-4)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-9 gnu)
#:use-module (srfi srfi-43)
#:use-module (system foreign)
#:use-module (gl)
#:use-module (gl low-level)
+ #:use-module (gl enums)
#:use-module (sly utils)
#:use-module (sly wrappers gl)
#:use-module (sly math vector)
#:use-module (sly render color)
#:use-module (sly render shader)
- #:export (make-vertex-buffer
+ #:export (make-streaming-vertex-buffer
+ make-vertex-buffer
bytevector->vertex-buffer
vector->vertex-buffer
vertex-buffer?
@@ -46,8 +49,11 @@
vertex-buffer-usage
vertex-buffer-data
vertex-buffer-length
+ vertex-buffer-element-length
vertex-buffer-attribute-size
apply-vertex-buffer
+ map-vertex-buffer!
+ unmap-vertex-buffer!
generate-vertex-array
vertex-attrib-pointer
@@ -68,17 +74,18 @@
;;;
(define-record-type <vertex-buffer>
- (%make-vertex-buffer id type usage data)
+ (%make-vertex-buffer id type usage length data)
vertex-buffer?
(id vertex-buffer-id)
(type vertex-buffer-type)
(usage vertex-buffer-usage)
- (data vertex-buffer-data))
+ (length vertex-buffer-length)
+ (data vertex-buffer-data set-vertex-buffer-data!))
(set-record-type-printer! <vertex-buffer>
(lambda (vbo port)
(format port
- "#<vertex-buffer id: ~d type: ~a usage: ~a"
+ "#<vertex-buffer id: ~d type: ~a usage: ~a>"
(vertex-buffer-id vbo)
(vertex-buffer-type vbo)
(vertex-buffer-usage vbo))))
@@ -173,7 +180,7 @@
(arb-vertex-buffer-object element-array-buffer-arb)
(arb-vertex-buffer-object array-buffer-arb)))
-(define (vertex-buffer-length vbo)
+(define (vertex-buffer-element-length vbo)
(/ (bytevector-length (vertex-buffer-data vbo))
(* (vertex-buffer-attribute-size vbo) 4)))
@@ -184,13 +191,22 @@
('stream
(arb-vertex-buffer-object stream-draw-arb))))
-(define (init-vertex-buffer-data! vbo)
- (let ((data (vertex-buffer-data vbo)))
+(define (make-streaming-vertex-buffer type length)
+ "Return a new vertex buffer of LENGTH elements suitable for
+streaming data to the GPU every frame. TYPE is a symbol specifying
+the element type, either 'float', 'index', 'vec2', 'vec3', or 'vec4'."
+ (let ((vbo (%make-vertex-buffer (generate-vertex-buffer)
+ type
+ 'stream
+ ;; All numbers are 32 bits e.g. 4 bytes
+ (* (type-size type) length 4)
+ #f)))
(with-vertex-buffer vbo
(glBufferData (vertex-buffer-target vbo)
- (bytevector-length data)
- (bytevector->pointer data)
- (vertex-buffer-usage-gl vbo)))))
+ length
+ %null-pointer
+ (vertex-buffer-usage-gl vbo)))
+ vbo))
(define (make-vertex-buffer type usage length)
(let ((data (if (eq? type 'index)
@@ -199,8 +215,16 @@
(bytevector->vertex-buffer type usage data)))
(define (bytevector->vertex-buffer type usage bv)
- (let ((vbo (%make-vertex-buffer (generate-vertex-buffer) type usage bv)))
- (init-vertex-buffer-data! vbo)
+ (let ((vbo (%make-vertex-buffer (generate-vertex-buffer)
+ type
+ usage
+ (bytevector-length bv)
+ bv)))
+ (with-vertex-buffer vbo
+ (glBufferData (vertex-buffer-target vbo)
+ (bytevector-length bv)
+ (bytevector->pointer bv)
+ (vertex-buffer-usage-gl vbo)))
vbo))
(define* (vector->vertex-buffer vertices #:optional (index? #f) (usage 'static))
@@ -210,6 +234,25 @@
(attribute-type (vector-ref vertices 0)))))
(bytevector->vertex-buffer type usage data)))
+(define (map-vertex-buffer! vbo)
+ "Map the memory space for VBO from GPU to the CPU, which is then
+accessible via the vertex-buffer-data procedure. This technique
+allows vertex buffers to be updated with new vertex data."
+ (let ((target (vertex-buffer-target vbo))
+ (length (vertex-buffer-length vbo))
+ (usage (vertex-buffer-usage-gl vbo)))
+ (with-vertex-buffer vbo
+ ;; Orphan the buffer to avoid implicit synchronization.
+ ;; See: https://www.opengl.org/wiki/Buffer_Object_Streaming#Buffer_re-specification
+ (glBufferData target length %null-pointer usage)
+ (let ((ptr (glMapBuffer target (version-1-5 read-write))))
+ (set-vertex-buffer-data! vbo (pointer->bytevector ptr length))))))
+
+(define (unmap-vertex-buffer! vbo)
+ "Return the mapped vertex data for VBO to the GPU."
+ (with-vertex-buffer vbo
+ (glUnmapBuffer (vertex-buffer-target vbo))))
+
;;;
;;; Mesh
;;;
@@ -258,7 +301,7 @@
(define (make-mesh index-buffer position-buffer texture-buffer)
(let ((mesh (%make-mesh (generate-vertex-array)
- (vertex-buffer-length index-buffer)
+ (vertex-buffer-element-length index-buffer)
`((index . ,index-buffer)
(position . ,position-buffer)
(texture . ,texture-buffer)))))