/*

ahbejarano

Shader wrapper class.

*/

package geetransit.minecraft05.engine;

import java.util.*;

import org.joml.*;

import org.lwjgl.system.*;

import static org.lwjgl.opengl.GL20.*;

public class Shader {

private final int programId;

private int vertexShaderId;

private int fragmentShaderId;

private final Map<String, Integer> uniforms;

public Shader() throws Exception {

this.programId = glCreateProgram();

if (this.programId == 0) {

throw new Exception("Could not create Shader");

}

this.uniforms = new HashMap<>();

}

public void createUniform(String name) throws Exception {

int location = glGetUniformLocation(this.programId, name);

if (location < 0) {

throw new Exception("Could not find uniform:" + name);

}

uniforms.put(name, location);

}

public void setUniform(String name, Matrix4f value) {

// Dump the matrix into a float buffer

try (MemoryStack stack = MemoryStack.stackPush()) {

glUniformMatrix4fv(uniforms.get(name), false, value.get(stack.mallocFloat(16)));

}

}

public void setUniform(String name, int value) {

glUniform1i(uniforms.get(name), value);

}

public void setUniform(String name, boolean value) {

glUniform1i(uniforms.get(name), value ? 1 : 0);

}

public void setUniform(String name, Vector3f value) {

glUniform3f(uniforms.get(name), value.x, value.y, value.z);

}

public void setUniform(String name, Vector4f value) {

glUniform4f(uniforms.get(name), value.x, value.y, value.z, value.w);

}

public void createVertexShader(String shaderCode) throws Exception {

this.vertexShaderId = createShader(shaderCode, GL_VERTEX_SHADER);

}

public void createFragmentShader(String shaderCode) throws Exception {

this.fragmentShaderId = createShader(shaderCode, GL_FRAGMENT_SHADER);

}

protected int createShader(String shaderCode, int shaderType) throws Exception {

int shaderId = glCreateShader(shaderType);

if (shaderId == 0) {

throw new Exception("Error creating shader. Type: " + shaderType);

}

glShaderSource(shaderId, shaderCode);

glCompileShader(shaderId);

if (glGetShaderi(shaderId, GL_COMPILE_STATUS) == 0) {

throw new Exception("Error compiling Shader code: " + glGetShaderInfoLog(shaderId, 1024));

}

glAttachShader(programId, shaderId);

return shaderId;

}

public void link() throws Exception {

glLinkProgram(this.programId);

if (glGetProgrami(this.programId, GL_LINK_STATUS) == 0) {

throw new Exception("Error linking Shader code: " + glGetProgramInfoLog(this.programId, 1024));

}

if (this.vertexShaderId != 0) {

glDetachShader(this.programId, this.vertexShaderId);

}

if (this.fragmentShaderId != 0) {

glDetachShader(this.programId, this.fragmentShaderId);

}

// definition in res/vertex.vs

// equivalent of `layout (location = #) ...`

glBindAttribLocation(this.programId, 0, "position");

glBindAttribLocation(this.programId, 1, "coords");

glValidateProgram(this.programId);

if (glGetProgrami(this.programId, GL_VALIDATE_STATUS) == 0) {

System.err.println("Warning validating Shader code: " + glGetProgramInfoLog(this.programId, 1024));

}

}

public void bind() {

glUseProgram(this.programId);

}

public void unbind() {

glUseProgram(0);

}

public void cleanup() {

this.unbind();

if (this.programId != 0) {

glDeleteProgram(this.programId);

}

}

}