shaders

README

Shaders

About

This package contains plain vertex and fragment shaders, version 1.30 (OpenGL 3.0), for Go. It is published on https://github.com/vbsw/shaders and https://gitlab.com/vbsw/shaders.

Copyright

Copyright 2020, Vitali Baumtrok (vbsw@mailbox.org).

Shaders is distributed under the Boost Software License, version 1.0. (See accompanying file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)

Shaders is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the Boost Software License for more details.

Examples

With this package:

import (
	"github.com/go-gl/gl/v3.3-core/gl"
	"gitlab.com/vbsw/shaders"
)

func main() {
	....
	shader := shaders.NewPrimitiveShader()
	shader.VertexShaderID = gl.CreateShader(gl.VERTEX_SHADER)
	gl.ShaderSource(shader.VertexShaderID, 1, shader.VertexShader, nil)
	....
}

Standard way:

import (
	"github.com/go-gl/gl/v3.3-core/gl"
)

func main() {
	....
	vertexShaderStr := "#version 130\nin vec3 vp;\nvoid main () {\n\tgl_Position = vec4(vp, 1.0);\n}"
	shaderID := gl.CreateShader(gl.VERTEX_SHADER)
	vertexShaderC, free := gl.Strs(vertexShaderStr + "\x00")
	gl.ShaderSource(shaderID, 1, vertexShaderC, nil)
	free()
	....
}

Initialize the projection matrix:

import (
	"github.com/go-gl/gl/v3.3-core/gl"
	"gitlab.com/vbsw/shaders"
)

func main() {
	....
	shader.ProjectionLocation = gl.GetUniformLocation(shader.ProgramID, shader.ProjectionUniform)
	gl.UseProgram(shader.ProgramID)
	setProjection(shader.ProjectionLocation, 400, 400)
	....
}

func setProjection(projectionLocation int32, width, height int) {
	projectionMatrix := make([]float32, 4*4)
	projectionMatrix[0] = 2.0 / float32(width)
	projectionMatrix[5] = 2.0 / float32(height)
	projectionMatrix[12] = -1.0
	projectionMatrix[13] = -1.0
	projectionMatrix[15] = 1.0
	gl.UniformMatrix4fv(projectionLocation, 1, false, &projectionMatrix[0]);
}

References

• https://golang.org/doc/install
• https://git-scm.com/book/en/v2/Getting-Started-Installing-Git
• https://www.khronos.org/registry/OpenGL/specs/gl/GLSLangSpec.1.30.pdf
• https://github.com/go-gl/gl/blob/master/v3.3-core/gl/conversions.go
• https://git.sr.ht/~eliasnaur/gio/tree/master/example/glfw/main.go

Documentation

Overview

Package shaders contains plain vertex and fragment shaders, version 1.30 (OpenGL 3.0).

Index

• func NewString(cstr *uint8) string
• type Shader
  • func NewPrimitiveShader() *Shader
  • func NewTextureShader() *Shader
  • func (shader *Shader) FragmentShaderStr() string
  • func (shader *Shader) VertexShaderStr() string

Functions

func NewString

func NewString(cstr *uint8) string

NewString converts c-string to string and returns it. Data of c-string is not reallocated, but used in string.

Types

type Shader

type Shader struct {
	VertexShader       **uint8
	FragmentShader     **uint8
	VertexShaderID     uint32
	FragmentShaderID   uint32
	ProgramID          uint32
	PositionAttribute  *uint8
	ColorAttribute     *uint8
	CoordsAttribute    *uint8
	ProjectionUniform  *uint8
	ModelUniform       *uint8
	TextureUniform     *uint8
	PositionLocation   int32
	ColorLocation      int32
	CoordsLocation     int32
	ProjectionLocation int32
	ModelLocation      int32
	TextureLocation    int32
}

Shader is for storing shaders and their attributes.

func NewPrimitiveShader

func NewPrimitiveShader() *Shader

NewPrimitiveShader returns an instance of Shader for primitive types.

Vertex shader:

#version 130

in vec3 positionIn;
in vec4 colorIn;
out vec4 fragementColor;

uniform mat4 projection = mat4(1.0);
uniform mat4 model = mat4(1.0);

void main() {
	gl_Position = projection * model * vec4(positionIn, 1.0f);
	fragementColor = colorIn;
}

Fragment shader:

#version 130

in vec4 fragementColor;
out vec4 color;

void main () {
	color = fragementColor;
}

func NewTextureShader

func NewTextureShader() *Shader

NewTextureShader returns an instance of Shader for textures.

Vertex shader:

#version 130

in vec3 positionIn;
in vec2 textureCoordsIn;
out vec2 fragmentTextureCoords;

uniform mat4 projection = mat4(1.0);
uniform mat4 model = mat4(1.0);

void main() {
	gl_Position = projection * model * vec4(positionIn, 1.0f);
	fragmentTextureCoords = textureCoordsIn;
}

Fragment shader:

#version 130

in vec2 fragmentTextureCoords;
out vec4 color;

uniform sampler2D imageTexture;

void main () {
	color = texture(imageTexture, fragmentTextureCoords);
}

func (*Shader) FragmentShaderStr

func (shader *Shader) FragmentShaderStr() string

FragmentShaderStr returns fragment shader as string.

func (*Shader) VertexShaderStr

func (shader *Shader) VertexShaderStr() string

VertexShaderStr returns vertex shader as string.