Ejemplo n.º 1
0
// BindFrame creates a framebuffer object with an associated texture.
//    http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-14-render-to-texture/
//    http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-16-shadow-mapping/
func (gc *opengl) BindFrame(buf int, fbo, tid, db *uint32) (err error) {
	size := int32(1024)
	gl.GenFramebuffers(1, fbo)
	gl.BindFramebuffer(gl.FRAMEBUFFER, *fbo)

	// Create a texture specifically for the framebuffer.
	gl.GenTextures(1, tid)
	gl.BindTexture(gl.TEXTURE_2D, *tid)
	switch buf {
	case IMAGE_BUFF:
		gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, size, size,
			0, gl.RGBA, gl.UNSIGNED_BYTE, gl.Pointer(nil))
		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)

		// Add a depth buffer to mimic the normal framebuffer behaviour for 3D objects.
		gl.GenRenderbuffers(1, db)
		gl.BindRenderbuffer(gl.RENDERBUFFER, *db)
		gl.RenderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT, size, size)
		gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, *db)

		// Associate the texture with the framebuffer.
		gl.FramebufferTexture(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, *tid, 0)
		buffType := uint32(gl.COLOR_ATTACHMENT0)
		gl.DrawBuffers(1, &buffType)
	case DEPTH_BUFF:
		gl.TexImage2D(gl.TEXTURE_2D, 0, gl.DEPTH_COMPONENT16, size, size,
			0, gl.DEPTH_COMPONENT, gl.FLOAT, gl.Pointer(nil))
		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_COMPARE_FUNC, gl.LEQUAL)
		gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_COMPARE_MODE, gl.COMPARE_REF_TO_TEXTURE)

		// Associate the texture with the framebuffer.
		gl.FramebufferTexture(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, *tid, 0)
		gl.DrawBuffer(gl.NONE)
	default:
		return fmt.Errorf("BindFrame unrecognized buffer type.")
	}

	// Report any problems.
	glerr := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
	if glerr != gl.FRAMEBUFFER_COMPLETE {
		return fmt.Errorf("BindFrame error %X", glerr)
	}
	if glerr := gl.GetError(); glerr != gl.NO_ERROR {
		err = fmt.Errorf("Failed binding framebuffer %X", glerr)
	}
	gl.BindFramebuffer(gl.FRAMEBUFFER, 0) // clean up by resetting to default framebuffer.
	return err
}
Ejemplo n.º 2
0
// Render implementation.
// FUTURE: all kinds of possible optimizations that would need to be
//         profiled before implementing.
//           • group by vao to avoid switching vao's.
//           • group by texture to avoid switching textures.
//           • use interleaved vertex data.
//           • uniform buffers http://www.opengl.org/wiki/Uniform_Buffer_Object.
//           • ... lots more possiblities... leave your fav here.
func (gc *opengl) Render(dr Draw) {
	d, ok := dr.(*draw)
	if !ok || d == nil {
		return
	}

	// switch state only if necessary.
	if gc.depthTest != d.depth {
		if d.depth {
			gl.Enable(gl.DEPTH_TEST)
		} else {
			gl.Disable(gl.DEPTH_TEST)
		}
		gc.depthTest = d.depth
	}

	// switch render framebuffer only if necessary. The framebuffer
	// is used to render to a texture associated with a framebuffer.
	if gc.fbo != d.fbo {
		gl.BindFramebuffer(gl.FRAMEBUFFER, d.fbo)
		if d.fbo == 0 {
			gl.Viewport(0, 0, gc.vw, gc.vh)
		} else {
			gl.Clear(gl.DEPTH_BUFFER_BIT)
			gl.Viewport(0, 0, 1024, 1024) // size convention for framebuffer texture.
		}
		gc.fbo = d.fbo
	}

	// switch shaders only if necessary.
	if gc.shader != d.shader {
		gl.UseProgram(d.shader)
		gc.shader = d.shader
	}

	// Ask the model to bind its provisioned uniforms.
	// FUTURE: only need to bind uniforms that have changed.
	gc.bindUniforms(d)

	// bind the data buffers and render.
	gl.BindVertexArray(d.vao)
	switch d.mode {
	case LINES:
		gl.PolygonMode(gl.FRONT_AND_BACK, gl.LINE)
		gl.DrawElements(gl.LINES, d.numFaces, gl.UNSIGNED_SHORT, 0)
		gl.PolygonMode(gl.FRONT_AND_BACK, gl.FILL)
	case POINTS:
		gl.Enable(gl.PROGRAM_POINT_SIZE)
		gl.DrawArrays(gl.POINTS, 0, d.numVerts)
		gl.Disable(gl.PROGRAM_POINT_SIZE)
	case TRIANGLES:
		if len(d.texs) > 1 && d.texs[0].fn > 0 {
			// Multiple textures on one model specify which verticies they apply to.
			for _, tex := range d.texs {
				// Use the same texture unit and sampler. Just update which
				// image is being sampled.
				gl.BindTexture(gl.TEXTURE_2D, tex.tid)
				// fn is the number of triangles, 3 indicies per triangle.
				// f0 is the offset in triangles where each triangle has 3 indicies
				//    of 2 bytes (uShort) each.
				gl.DrawElements(gl.TRIANGLES, tex.fn*3, gl.UNSIGNED_SHORT, int64(3*2*tex.f0))
			}
		} else {
			// Single textures are handled with a standard bindUniforms
			gl.DrawElements(gl.TRIANGLES, d.numFaces, gl.UNSIGNED_SHORT, 0)
		}
	}
}