ml
63 lines
1.6 KiB
Go
63 lines
1.6 KiB
Go
package opengl
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// AttributeSetter is a callback function for a VertexArrayObject.
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type AttributeSetter func(OpenGL)
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// VertexArrayObject registers common vertex properties which are pre-set
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// before regular rendering loops.
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// Depending on the supported level of the Open GL API, these settings are
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// either buffered (using a VAO - vertex array object), or replayed for
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// every render call.
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type VertexArrayObject struct {
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gl OpenGL
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program uint32
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handle uint32
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setter AttributeSetter
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}
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// NewVertexArrayObject returns a new instance.
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func NewVertexArrayObject(gl OpenGL, program uint32) *VertexArrayObject {
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vao := &VertexArrayObject{
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gl: gl,
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program: program,
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handle: gl.GenVertexArrays(1)[0],
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setter: func(OpenGL) {}}
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return vao
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}
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// Dispose drops any associated resources.
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func (vao *VertexArrayObject) Dispose() {
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vao.gl.DeleteVertexArrays([]uint32{vao.handle})
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vao.handle = 0
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}
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// WithSetter registers the setter function for this object.
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// Depending on the support of the OpenGL API, this setter may be called
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// once immediately, or for each render call.
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func (vao *VertexArrayObject) WithSetter(setter AttributeSetter) {
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if vao.handle != 0 {
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vao.OnShader(func() { setter(vao.gl) })
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}
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vao.setter = setter
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}
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// OnShader executes the provided task with an activated shader program
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// and the vertex array object initialized.
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func (vao *VertexArrayObject) OnShader(task func()) {
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gl := vao.gl
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gl.UseProgram(vao.program)
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gl.BindVertexArray(vao.handle)
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defer func() {
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gl.BindVertexArray(0)
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gl.UseProgram(0)
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}()
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if vao.handle == 0 {
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vao.setter(gl)
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}
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task()
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}
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