opengl水波纹效果纯色背景问题？

wensefu 2013-07-18 04:42:24

我用glsl弄的水波纹效果，
但是现在发现当背景是纯色的时候就看不出水波效果了，
有没有大神给个解决思路啊！！

GLSL:







#pragma version(1)



#pragma rs java_package_name(com.android.systemui)



#include "rs_graphics.rsh"



// Things we need to set from the application

float g_glWidth;

float g_glHeight;

float g_meshWidth;

float g_meshHeight;

float g_xOffset;

float g_rotate;



rs_program_vertex g_PVWater;

rs_program_vertex g_PVSky;



rs_program_fragment g_PFSky;

rs_program_fragment g_PFBackground;



rs_allocation g_TRiverbed;



rs_mesh g_WaterMesh;





typedef struct Constants {

    float4 Drop01;

    float4 Drop02;

    float4 Drop03;

    float4 Drop04;

    float4 Drop05;

    float4 Drop06;

    float4 Drop07;

    float4 Drop08;

    float4 Drop09;

    float4 Drop10;

    float4 Offset;

    float Rotate;

} Constants_t;



Constants_t *g_Constants;

rs_program_store g_PFSBackground;



//float skyOffsetX;

//float skyOffsetY;

static float g_DT;

static int64_t g_LastTime;



typedef struct Drop {

    float ampS;

    float ampE;

    float spread;

    float x;

    float y;

} Drop_t;

static Drop_t gDrops[10];

static int gMaxDrops;





void init() {

    int ct;

    gMaxDrops = 10;

    for (ct=0; ct<gMaxDrops; ct++) {

        gDrops[ct].ampS = 0;

        gDrops[ct].ampE = 0;

        gDrops[ct].spread = 1;

    }

    g_LastTime = rsUptimeMillis();

    g_DT = 0.1f;

}



static void updateDrop(int ct) {

    gDrops[ct].spread += 30.f * g_DT;

    gDrops[ct].ampE = gDrops[ct].ampS / gDrops[ct].spread;

}



static void drop(int x, int y, float s) {

    int ct;

    int iMin = 0;

    float minAmp = 3000.f;

    for (ct = 0; ct < gMaxDrops; ct++) {

        if (gDrops[ct].ampE < minAmp) {

            iMin = ct;

            minAmp = gDrops[ct].ampE;

        }

    }

    gDrops[iMin].ampS = s;

    gDrops[iMin].spread = 0;

    gDrops[iMin].x = x;

    gDrops[iMin].y = g_meshHeight - y - 1;

    updateDrop(iMin);

}





static void generateRipples() {

    int ct;

    for (ct = 0; ct < gMaxDrops; ct++) {

        Drop_t * d = &gDrops[ct];

        float *v = (float*)&g_Constants->Drop01;

        v += ct*4;

        *(v++) = d->x;

        *(v++) = d->y;

        *(v++) = d->ampE * 0.22f;

        *(v++) = d->spread;

    }

    g_Constants->Offset.x = g_xOffset;



    for (ct = 0; ct < gMaxDrops; ct++) {

        updateDrop(ct);

    }

}



//绘制水中的倒影

static void drawRiverbed() {

    rsgBindProgramFragment(g_PFBackground);

    rsgBindProgramStore(g_PFSBackground);

    rsgBindTexture(g_PFBackground, 0, g_TRiverbed);

    rsgDrawMesh(g_WaterMesh);

}





void addDrop(int x, int y) {

    drop(x, y, 6);

}





int root(void) {

    rsgClearColor(0.f, 0.f, 0.f, 2.f);



    // Compute dt in seconds.

    int64_t newTime = rsUptimeMillis();

    g_DT = (newTime - g_LastTime) * 0.001f;

    g_DT = min(g_DT, 0.2f);

    g_LastTime = newTime;



    g_Constants->Rotate = (float) g_rotate;





    rsgBindProgramVertex(g_PVWater);

    generateRipples();

    rsgAllocationSyncAll(rsGetAllocation(g_Constants));

    drawRiverbed();



    return 50;

}