org.lwjgl.opengl.EXTSeparateShaderObjects Maven / Gradle / Ivy

/*
 * Copyright LWJGL. All rights reserved.
 * License terms: https://www.lwjgl.org/license
 * MACHINE GENERATED FILE, DO NOT EDIT
 */
package org.lwjgl.opengl;

import java.nio.*;

import org.lwjgl.system.*;

import static org.lwjgl.system.Checks.*;
import static org.lwjgl.system.MemoryStack.*;
import static org.lwjgl.system.MemoryUtil.*;

/**
 * Native bindings to the EXT_separate_shader_objects extension.
 * 
 * rior to this extension, GLSL requires multiple shader domains (vertex, fragment, geometry) to be linked into a single monolithic program object to
 * specify a GLSL shader for each domain.
 * 
 * While GLSL's monolithic approach has some advantages for optimizing shaders as a unit that span multiple domains, all existing GPU hardware supports
 * the more flexible mix-and-match approach.
 * 
 * HLSL9, Cg, the prior OpenGL assembly program extensions, and game console programmers favor a more flexible "mix-and-match" approach to specifying
 * shaders independently for these different shader domains. Many developers build their shader content around the mix-and-match approach where they can
 * use a single vertex shader with multiple fragment shaders (or vice versa).
 * 
 * This keep-it-simple extension adapts the "mix-and-match" shader domain model for GLSL so different GLSL program objects can be bound to different
 * shader domains.
 * 
 * This extension redefines the operation of glUseProgram(GLenum program) to be equivalent to:
 * 
 *  *  glUseShaderProgramEXT(GL_VERTEX_SHADER, program);
 * glUseShaderProgramEXT(GL_GEOMETRY_SHADER_EXT, program);
 * glUseShaderProgramEXT(GL_FRAGMENT_SHADER, program);
 * glActiveProgramEXT(program);
 * 
 * You can also call these commands separately to bind each respective domain. The GL_VERTEX_SHADER, GL_GEOMETRY_SHADER_EXT, and GL_FRAGMENT_SHADER tokens
 * refer to the conventional vertex, geometry, and fragment domains respectively. glActiveProgramEXT specifies the program that glUniform* commands will
 * update.
 * 
 * Separate linking creates the possibility that certain output varyings of a shader may go unread by the subsequent shader inputting varyings. In this
 * case, the output varyings are simply ignored. It is also possible input varyings from a shader may not be written as output varyings of a preceding
 * shader. In this case, the unwritten input varying values are undefined. Implementations are encouraged to zero these undefined input varying values.
 * 
 * This extension is a proof-of-concept that separate shader objects can work for GLSL and a response to repeated requests for this functionality. There
 * are various loose ends, particularly when dealing with user-defined varyings. The hope is a future extension will improve this situation.
 * 
 * Requires {@link GL20 OpenGL 2.0} or {@link ARBShaderObjects ARB_shader_objects}.
 */
public class EXTSeparateShaderObjects {

    /** Accepted by {@code type} parameter to GetIntegerv and GetFloatv. */
    public static final int GL_ACTIVE_PROGRAM_EXT = 0x8B8D;

    static { GL.initialize(); }

    protected EXTSeparateShaderObjects() {
        throw new UnsupportedOperationException();
    }

    static boolean isAvailable(GLCapabilities caps) {
        return checkFunctions(
            caps.glUseShaderProgramEXT, caps.glActiveProgramEXT, caps.glCreateShaderProgramEXT
        );
    }

    // --- [ glUseShaderProgramEXT ] ---

    public static native void glUseShaderProgramEXT(int type, int program);

    // --- [ glActiveProgramEXT ] ---

    public static native void glActiveProgramEXT(int program);

    // --- [ glCreateShaderProgramEXT ] ---

    public static native int nglCreateShaderProgramEXT(int type, long string);

    public static int glCreateShaderProgramEXT(int type, ByteBuffer string) {
        if (CHECKS) {
            checkNT1(string);
        }
        return nglCreateShaderProgramEXT(type, memAddress(string));
    }

    public static int glCreateShaderProgramEXT(int type, CharSequence string) {
        MemoryStack stack = stackGet(); int stackPointer = stack.getPointer();
        try {
            ByteBuffer stringEncoded = stack.UTF8(string);
            return nglCreateShaderProgramEXT(type, memAddress(stringEncoded));
        } finally {
            stack.setPointer(stackPointer);
        }
    }

}