GLScaler.cc

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#include "GLScaler.hh"
#include "GLUtil.hh"
#include "memory.hh"

namespace openmsx {

GLScaler::GLScaler()
{
        VertexShader   vertexShader  ("superImpose.vert");
        FragmentShader fragmentShader("superImpose.frag");
        scalerProgram.attach(vertexShader);
        scalerProgram.attach(fragmentShader);
        scalerProgram.link();
#ifdef GL_VERSION_2_0
        if (GLEW_VERSION_2_0) {
                scalerProgram.activate();
                glUniform1i(scalerProgram.getUniformLocation("tex"), 0);
                glUniform1i(scalerProgram.getUniformLocation("videoTex"), 1);
        }
#endif
}

GLScaler::~GLScaler()
{
}

void GLScaler::uploadBlock(
        unsigned /*srcStartY*/, unsigned /*srcEndY*/,
        unsigned /*lineWidth*/, FrameSource& /*paintFrame*/)
{
}

void GLScaler::scaleImage(
        ColorTexture& src, ColorTexture* superImpose,
        unsigned srcStartY, unsigned srcEndY, unsigned /*srcWidth*/,
        unsigned dstStartY, unsigned dstEndY, unsigned dstWidth,
        unsigned logSrcHeight)
{
        if (superImpose) {
                glActiveTexture(GL_TEXTURE1);
                superImpose->bind();
                glActiveTexture(GL_TEXTURE0);
                scalerProgram.activate();
        } else {
                scalerProgram.deactivate();
        }

        drawMultiTex(src, srcStartY, srcEndY, src.getHeight(), logSrcHeight,
                     dstStartY, dstEndY, dstWidth);
}

void GLScaler::drawMultiTex(
        ColorTexture& src,
        unsigned srcStartY, unsigned srcEndY,
        float physSrcHeight, float logSrcHeight,
        unsigned dstStartY, unsigned dstEndY, unsigned dstWidth,
        bool textureFromZero)
{
        src.bind();
        // Note: hShift is pre-divided by srcWidth, while vShift will be divided
        //       by srcHeight later on.
        // Note: The coordinate is put just past zero, to avoid fract() in the
        //       fragment shader to wrap around on rounding errors.
        float hShift = textureFromZero ? 0.501f / dstWidth : 0.0f;
        float vShift = textureFromZero ? 0.501f * (
                float(srcEndY - srcStartY) / float(dstEndY - dstStartY)
                ) : 0.0f;
        glEnable(GL_TEXTURE_2D);
        glBegin(GL_QUADS);
        {
                GLfloat tex0StartY = (srcStartY + vShift) / physSrcHeight;
                GLfloat tex0EndY   = (srcEndY   + vShift) / physSrcHeight;
                GLfloat tex1StartY = (srcStartY + vShift) / logSrcHeight;
                GLfloat tex1EndY   = (srcEndY   + vShift) / logSrcHeight;

                glMultiTexCoord2f(GL_TEXTURE0, 0.0f + hShift, tex0StartY);
                glMultiTexCoord2f(GL_TEXTURE1, 0.0f + hShift, tex1StartY);
                glVertex2i(       0, dstStartY);

                glMultiTexCoord2f(GL_TEXTURE0, 1.0f + hShift, tex0StartY);
                glMultiTexCoord2f(GL_TEXTURE1, 1.0f + hShift, tex1StartY);
                glVertex2i(dstWidth, dstStartY);

                glMultiTexCoord2f(GL_TEXTURE0, 1.0f + hShift, tex0EndY  );
                glMultiTexCoord2f(GL_TEXTURE1, 1.0f + hShift, tex1EndY  );
                glVertex2i(dstWidth, dstEndY  );

                glMultiTexCoord2f(GL_TEXTURE0, 0.0f + hShift, tex0EndY  );
                glMultiTexCoord2f(GL_TEXTURE1, 0.0f + hShift, tex1EndY  );
                glVertex2i(       0, dstEndY  );
        }
        glEnd();
        glDisable(GL_TEXTURE_2D);
}

} // namespace openmsx