ebiten/internal/graphics/program.go

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// Copyright 2014 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
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package graphics
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import (
"fmt"
"github.com/hajimehoshi/ebiten/internal/affine"
"github.com/hajimehoshi/ebiten/internal/opengl"
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)
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// arrayBufferLayoutPart is a part of an array buffer layout.
type arrayBufferLayoutPart struct {
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// TODO: This struct should belong to a program and know it.
name string
dataType opengl.DataType
num int
}
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// arrayBufferLayout is an array buffer layout.
//
// An array buffer in OpenGL is a buffer representing vertices and
// is passed to a vertex shader.
type arrayBufferLayout struct {
parts []arrayBufferLayoutPart
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total int
}
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// totalBytes returns the size in bytes for one element of the array buffer.
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func (a *arrayBufferLayout) totalBytes() int {
if a.total != 0 {
return a.total
}
t := 0
for _, p := range a.parts {
t += p.dataType.SizeInBytes() * p.num
}
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a.total = t
return a.total
}
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// newArrayBuffer creates OpenGL's buffer object for the array buffer.
func (a *arrayBufferLayout) newArrayBuffer() opengl.Buffer {
return opengl.GetContext().NewArrayBuffer(a.totalBytes() * 4 * maxQuads)
}
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// enable binds the array buffer the given program to use the array buffer.
func (a *arrayBufferLayout) enable(program opengl.Program) {
for _, p := range a.parts {
opengl.GetContext().EnableVertexAttribArray(program, p.name)
}
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total := a.totalBytes()
offset := 0
for _, p := range a.parts {
opengl.GetContext().VertexAttribPointer(program, p.name, p.num, p.dataType, total, offset)
offset += p.dataType.SizeInBytes() * p.num
}
}
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// disable stops using the array buffer.
func (a *arrayBufferLayout) disable(program opengl.Program) {
// TODO: Disabling should be done in reversed order?
for _, p := range a.parts {
opengl.GetContext().DisableVertexAttribArray(program, p.name)
}
}
var (
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// theArrayBufferLayout is the array buffer layout for Ebiten.
theArrayBufferLayout = arrayBufferLayout{
// Note that GL_MAX_VERTEX_ATTRIBS is at least 16.
parts: []arrayBufferLayoutPart{
{
name: "vertex",
dataType: opengl.Float,
num: 2,
},
{
name: "tex_coord",
dataType: opengl.Float,
num: 4,
},
{
name: "geo_matrix_body",
dataType: opengl.Float,
num: 4,
},
{
name: "geo_matrix_translation",
dataType: opengl.Float,
num: 2,
},
},
}
)
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// openGLState is a state for OpenGL.
type openGLState struct {
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// arrayBuffer is OpenGL's array buffer (vertices data).
arrayBuffer opengl.Buffer
// elementArrayBuffer is OpenGL's element array buffer (indices data).
elementArrayBuffer opengl.Buffer
// programTexture is OpenGL's program for rendering a texture.
programTexture opengl.Program
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lastProgram opengl.Program
lastProjectionMatrix []float32
lastColorMatrix []float32
lastColorMatrixTranslation []float32
}
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var (
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// theOpenGLState is the OpenGL state in the current process.
theOpenGLState openGLState
zeroBuffer opengl.Buffer
zeroProgram opengl.Program
)
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const (
indicesNum = 1 << 16
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maxQuads = indicesNum / 6
)
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// ResetGLState resets or initializes the current OpenGL state.
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func ResetGLState() error {
return theOpenGLState.reset()
}
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// reset resets or initializes the OpenGL state.
func (s *openGLState) reset() error {
if err := opengl.GetContext().Reset(); err != nil {
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return err
}
s.lastProgram = zeroProgram
s.lastProjectionMatrix = nil
s.lastColorMatrix = nil
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s.lastColorMatrixTranslation = nil
// When context lost happens, deleting programs or buffers is not necessary.
// However, it is not assumed that reset is called only when context lost happens.
// Let's delete them explicitly.
if s.programTexture != zeroProgram {
opengl.GetContext().DeleteProgram(s.programTexture)
}
if s.arrayBuffer != zeroBuffer {
opengl.GetContext().DeleteBuffer(s.arrayBuffer)
}
if s.elementArrayBuffer != zeroBuffer {
opengl.GetContext().DeleteBuffer(s.elementArrayBuffer)
}
shaderVertexModelviewNative, err := opengl.GetContext().NewShader(opengl.VertexShader, shader(shaderVertexModelview))
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if err != nil {
panic(fmt.Sprintf("graphics: shader compiling error:\n%s", err))
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}
defer opengl.GetContext().DeleteShader(shaderVertexModelviewNative)
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shaderFragmentTextureNative, err := opengl.GetContext().NewShader(opengl.FragmentShader, shader(shaderFragmentTexture))
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if err != nil {
panic(fmt.Sprintf("graphics: shader compiling error:\n%s", err))
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}
defer opengl.GetContext().DeleteShader(shaderFragmentTextureNative)
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s.programTexture, err = opengl.GetContext().NewProgram([]opengl.Shader{
shaderVertexModelviewNative,
shaderFragmentTextureNative,
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})
if err != nil {
return err
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}
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s.arrayBuffer = theArrayBufferLayout.newArrayBuffer()
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indices := make([]uint16, 6*maxQuads)
for i := uint16(0); i < maxQuads; i++ {
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indices[6*i+0] = 4*i + 0
indices[6*i+1] = 4*i + 1
indices[6*i+2] = 4*i + 2
indices[6*i+3] = 4*i + 1
indices[6*i+4] = 4*i + 2
indices[6*i+5] = 4*i + 3
}
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s.elementArrayBuffer = opengl.GetContext().NewElementArrayBuffer(indices)
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return nil
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}
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// areSameFloat32Array returns a boolean indicating if a and b are deeply equal.
func areSameFloat32Array(a, b []float32) bool {
if len(a) != len(b) {
return false
}
for i := 0; i < len(a); i++ {
if a[i] != b[i] {
return false
}
}
return true
}
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// useProgram uses the program (programTexture).
func (s *openGLState) useProgram(proj []float32, texture opengl.Texture, colorM affine.ColorM) {
c := opengl.GetContext()
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program := s.programTexture
if s.lastProgram != program {
c.UseProgram(program)
if s.lastProgram != zeroProgram {
theArrayBufferLayout.disable(s.lastProgram)
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}
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theArrayBufferLayout.enable(program)
s.lastProgram = s.programTexture
s.lastProjectionMatrix = nil
s.lastColorMatrix = nil
s.lastColorMatrixTranslation = nil
c.BindElementArrayBuffer(s.elementArrayBuffer)
c.UniformInt(program, "texture", 0)
}
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if !areSameFloat32Array(s.lastProjectionMatrix, proj) {
c.UniformFloats(program, "projection_matrix", proj)
if s.lastProjectionMatrix == nil {
s.lastProjectionMatrix = make([]float32, 16)
}
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copy(s.lastProjectionMatrix, proj)
}
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e := [4][5]float32{}
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es := colorM.UnsafeElements()
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for i := 0; i < 4; i++ {
for j := 0; j < 5; j++ {
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e[i][j] = float32(es[i*affine.ColorMDim+j])
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}
}
colorMatrix := []float32{
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e[0][0], e[1][0], e[2][0], e[3][0],
e[0][1], e[1][1], e[2][1], e[3][1],
e[0][2], e[1][2], e[2][2], e[3][2],
e[0][3], e[1][3], e[2][3], e[3][3],
}
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if !areSameFloat32Array(s.lastColorMatrix, colorMatrix) {
c.UniformFloats(program, "color_matrix", colorMatrix)
if s.lastColorMatrix == nil {
s.lastColorMatrix = make([]float32, 16)
}
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copy(s.lastColorMatrix, colorMatrix)
}
colorMatrixTranslation := []float32{
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e[0][4], e[1][4], e[2][4], e[3][4],
}
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if !areSameFloat32Array(s.lastColorMatrixTranslation, colorMatrixTranslation) {
c.UniformFloats(program, "color_matrix_translation", colorMatrixTranslation)
if s.lastColorMatrixTranslation == nil {
s.lastColorMatrixTranslation = make([]float32, 4)
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}
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copy(s.lastColorMatrixTranslation, colorMatrixTranslation)
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}
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// We don't have to call gl.ActiveTexture here: GL_TEXTURE0 is the default active texture
// See also: https://www.opengl.org/sdk/docs/man2/xhtml/glActiveTexture.xml
c.BindTexture(texture)
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}