ep2: Finish input system+opengl window+glsl compilation

shaders/shaders.go

@@ -0,0 +1,73 @@
+package shaders
+
+import (
+	"os"
+	"strings"
+
+	"github.com/bloeys/go-sdl-engine/logging"
+	"github.com/go-gl/gl/v4.6-compatibility/gl"
+)
+
+type ShaderProgram struct {
+	ID           uint32
+	VertShaderID uint32
+	FragShaderID uint32
+}
+
+func LoadShaders() {
+
+	vertShaderText, err := os.ReadFile("./res/shaders/simple.vert.glsl")
+	if err != nil {
+		logging.ErrLog.Fatalln("Failed to read vertex shader. Err: ", err)
+	}
+
+	fragShaderText, err := os.ReadFile("./res/shaders/simple.frag.glsl")
+	if err != nil {
+		logging.ErrLog.Fatalln("Failed to read fragment shader. Err: ", err)
+	}
+
+	shader := &ShaderProgram{}
+	shader.ID = gl.CreateProgram()
+	if shader.ID == 0 {
+		logging.ErrLog.Fatalln("Failed to create shader program")
+	}
+
+	shader.VertShaderID = gl.CreateShader(gl.VERTEX_SHADER)
+	shader.FragShaderID = gl.CreateShader(gl.FRAGMENT_SHADER)
+
+	vertexCStr, vertFree := gl.Strs(string(vertShaderText) + "\x00")
+	defer vertFree()
+	gl.ShaderSource(shader.VertShaderID, 1, vertexCStr, nil)
+
+	fragCStr, fragFree := gl.Strs(string(fragShaderText) + "\x00")
+	defer fragFree()
+	gl.ShaderSource(shader.FragShaderID, 1, fragCStr, nil)
+
+	gl.CompileShader(shader.VertShaderID)
+	getShaderCompileErrors(shader.VertShaderID)
+
+	gl.CompileShader(shader.FragShaderID)
+	getShaderCompileErrors(shader.FragShaderID)
+
+	gl.AttachShader(shader.ID, shader.VertShaderID)
+	gl.AttachShader(shader.ID, shader.FragShaderID)
+	gl.LinkProgram(shader.ID)
+}
+
+func getShaderCompileErrors(shaderID uint32) {
+
+	var compiledSuccessfully int32
+	gl.GetShaderiv(shaderID, gl.COMPILE_STATUS, &compiledSuccessfully)
+	if compiledSuccessfully == gl.TRUE {
+		return
+	}
+
+	var logLength int32
+	gl.GetShaderiv(shaderID, gl.INFO_LOG_LENGTH, &logLength)
+
+	log := gl.Str(strings.Repeat("\x00", int(logLength)))
+	gl.GetShaderInfoLog(shaderID, logLength, nil, log)
+
+	errMsg := gl.GoStr(log)
+	println("Compilation of shader with id ", shaderID, " failed. Err: ", errMsg)
+}